Multi Tech Systems Network Card MT3334HD8 User Manual

MT3334HD8 Modem

User Guide

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Federal Communications Commission Statement

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant

to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful

interference when the equipment is operated in a commercial environment. This equipment generates,

uses, and can radiate radio frequency energy, and if not installed and used in accordance with the

instruction manual, may cause harmful interference to radio communications. Operation of this

equipment in a residential area is likely to cause harmful interference, in which case the user will be

required to correct the interference at his own expense.

Warning: Changes or modifications to this unit not expressly approved by the party responsible for

compliance could void the user’s authority to operate the equipment.

FCC Regulations for Telephone Line Interconnection

1. No repairs are to be made by you. Repairs are to be made only by Multi-Tech Systems or its

licensees. Unauthorized repairs void registration and warranty. Contact Multi-Tech Systems, Inc. for

details of how to have repairs made.

2. When trouble is experienced, you must disconnect your modem from the telephone company’s jack

to determine the cause of the trouble, and reconnect your modem only when the trouble is

corrected.

3. The modem cannot be connected to pay telephones or party lines.

4. If requested by the telephone company, you must notify them of the following before the

MT3334HD8 is installed:

a. The particular phone line (phone number) to which the connection is to be made.

b. The FCC Registration Number:

AU7USA-24457-DE-N

c. The manufacturer’s name and model number:

Multi-Tech Systems - Model CC9600 CommPlete Communications Server

5. If the telephone company notifies you that your device is causing harm, unplug it. The telephone

company may disconnect your service if necessary and also may change its facilities, equipment,

operations or procedures which may affect operation of your equipment. Where practical, the

telephone company must promptly inform you in writing of the temporary disconnect or change in

service, give you the opportunity to make changes allowing uninterrupted service, and inform you of

your rights to bring a complaint to the FCC.

CommPlete Communications Server

iii

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FCC Fax Warning

The Telephone Consumer Protection Act of 1991 makes it unlawful for any person to use a computer or

other electronic device to send any message via a telephone fax machine unless such message clearly

contains in a margin at the top or bottom of each page or the first page of the transmission, the date and

time it is sent and an identification of the business or other entity, or other individual sending the message

and the telephone number of the sending machine or such business, other entity, or individual.

See your fax software manual for setup details.

Canadian Limitations Notice

Notice: The ringer equivalence number (REN) assigned to each terminal device provides an indication of

the maximum number of terminals allowed to be connected to a telephone interface. The termination of

an interface may consist of any combination of devices subject only to the requirement that the sum of the

ringer equivalence numbers of all the devices does not exceed 5.

Notice: The Industry Canada label identifies certificated equipment. This certification means that the

equipment meets certain telecommunications network protective, operational and safety requirements.

Industry Canada does not guarantee the equipment will operate to the user’s satisfaction.

Before installing this equipment, users should ensure that it is permissible to be connected to the facilities

of the local telecommunications company. The equipment must also be installed using an acceptable

method of connection. The customer should be aware that compliance with the above conditions may not

prevent degradation of service in some situations.

Repairs to certified equipment should be made by an authorized Canadian maintenance facility designated

by the supplier. Any repairs or alterations made by the user to this equipment, or equipment

malfunctions, may give the telecommunications company cause to request the user to disconnect the

equipment.

Users should ensure for their own protection that the electrical ground connections of the power utility,

telephone lines and internal metallic water pipe system, if present, are connected together. This precaution

may be particularly important in rural areas.

Caution: Users should not attempt to make such connections themselves, but should contact the

appropriate electric inspection authority, or electrician, as appropriate.

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Table of Contents

1 Introduction

Introduction ...................................................................................................................................................... 2

LED Indicators................................................................................................................................................... 2

Power Supply..................................................................................................................................................... 2

Manual Organization......................................................................................................................................... 3

Technical Specifications.................................................................................................................................... 6

2 Installation

Introduction ...................................................................................................................................................... 8

Safety Warnings................................................................................................................................................. 8

Pre-Installation Notes ....................................................................................................................................... 9

Installation Procedure....................................................................................................................................... 9

3 AT Commands

Working with AT Commands ..........................................................................................................................12

Modes of Operation .....................................................................................................................................12

Command Structure ....................................................................................................................................12

Command Editing........................................................................................................................................13

Dialing Commands...........................................................................................................................................16

Dial Modifier Commands.................................................................................................................................16

Phone Number Memory Commands...............................................................................................................19

Configuration Storage and Recall Commands.................................................................................................20

Modem Response (Result Code) Commands..................................................................................................21

Online Connection Commands........................................................................................................................24

V.34 Commands ...............................................................................................................................................28

RS-232 Interface Commands ...........................................................................................................................29

Error Correction and Data Compression Commands.....................................................................................31

Speed Conversion Commands .........................................................................................................................33

Immediate Action Commands.........................................................................................................................35

Flow Control Commands .................................................................................................................................36

Escape Sequences .............................................................................................................................................39

Remote Configuration Commands ..................................................................................................................40

Line Probe Commands.....................................................................................................................................41

Diagnostic Commands .....................................................................................................................................42

4 S-Registers

Introduction .....................................................................................................................................................46

S-Registers ........................................................................................................................................................46

Reading and Assigning S-Register Values .......................................................................................................51

Examples of Assigning Values.....................................................................................................................51

Examples of Reading Values .......................................................................................................................51

AT Commands that Affect S-Registers ............................................................................................................51

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5 Testing the MT3334HD8

Introduction .....................................................................................................................................................54

Local Analog Loopback Test (V.54 Loop 3) ....................................................................................................54

Remote Digital Loopback Test (V.54 Loop 2) .................................................................................................55

Local Digital Loopback Test (V.54 Loop 2) .....................................................................................................57

6 Warranty, Service, and Technical Support

Limited Warranty.............................................................................................................................................60

Service...............................................................................................................................................................61

Technical Support ............................................................................................................................................61

Recording Product Information .................................................................................................................61

The Multi-Tech BBS.........................................................................................................................................62

Logging onto the Multi-Tech BBS...............................................................................................................62

Downloading a File......................................................................................................................................62

Reading a Message.......................................................................................................................................63

Leaving a Message .......................................................................................................................................63

Bulletins.......................................................................................................................................................63

About CompuServe ..........................................................................................................................................63

About the Internet............................................................................................................................................64

About the Multi-Tech Fax-Back Service..........................................................................................................64

Upgrading the MT3334HD8 Firmware............................................................................................................65

Using FlashPro to Upgrade Firmware ........................................................................................................65

Appendix A ASCII Conversion Chart.......................................................68

Appendix B Dial Pulses and Tones...........................................................69

Appendix C Result Code Summary...........................................................71

Appendix D S-Register Summary................................................................73

Appendix E AT Command Summary.......................................................75

Appendix F Remote Configuration.............................................................85

Index.........................................................................................................................................................87

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1 Introduction

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MT3334HD8 User Guide

Introduction

The Multi-Tech MT3334HD8 is a high speed, high density modem card for the CommPlete

Communications Server. Each MT3334HD8 card contains eight integrated 33,600 bps modems. Each

modem on the MT3334HD8 card can be configured independently of the others via the CommPlete

Communications Server’s MR9600 controller, which can support and control up to 12 cards per rack.

Users dial into the MT3334HD8’s modems through a T1 daughter card on the RASCard that controls the

segment. There are no external connectors on the MT3334HD8.

Up to three MT3334HD8 cards can be installed per T1 segment. With eight modems per card, the

CommPlete Communications Server can support up to 24 simultaneous data lines per segment, or 96 per

CommPlete Communications Server

The MT3334HD8 operates as an enhanced ITU-T V.34 dial-up modem with a maximum speed of 33,600

bits per second (bps). As such, it includes the advanced features of Multi-Tech standalone modems such as

the popular MultiModemZDXb.

The MT3334HD8 is registered by the FCC for direct connection to the public telephone networks. No Data

Access Arrangements (DAAs) are required.

The MT3334HD8 is fully compatible with the standard AT command set, and is therefore compatible with

all popular communications software packages.

This user guide will help you to install, configure, test, and use the MT3334HD8.

LED Indicators

The MT3334HD8 has 16 LED indicators on the front panel, two for each modem:

CD Carrier Detect. The CD LED lights when the modem detects a valid carrier signal.

OH Off Hook/Out of Service. The OH LED lights when the modem is off hook, which occurs when the

modem is dialing, online, or answering a call. The LED flashes when the modem is in the busy-out

or out-of-service state.

Power Supplies

DC voltages are supplied to all modems in the CC9600 rack through two PS9600 universal input switching

power supplies designed for conventional 115 or 230 VAC input. The power supplies are designed for

redundant, fail-safe operation. If one should fail, the other can supply the power requirements of the entire

CommPlete Communications Server. Each PS9600 power supply has one LED indicator that indicates the

presence of all supply voltages.

Manual Organization

Chapter 1 Introduction

This chapter describes the MT3334HD8 and its LED indicators, gives its technical specifications, and

provides a guide to the organization of the manual.

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Introduction

Chapter 2 Installation

This chapter describes how to install the MT3334HD8 into the CC9600 chassis.

Chapter 3 Command Mode Operation

This chapter provides an introduction to MT3334HD8 command mode fundamentals, followed by a

detailed explanation of each AT command, providing examples where applicable.

Chapter 4 S-Registers

This chapter describes the MT3334HD8’s S-registers, which are used to store various modem options.

Each S-register is defined and explained.

Chapter 5 Testing the MT3334HD8

This chapter describes loopback testing for the MT3334HD8.

Chapter 6 Warranty, Service, and Technical Support

This chapter provides the terms of the MT3334HD8’s warranty, instructions for obtaining factory service,

and information about Multi-Tech’s BBS and technical support. Information on upgrading the

MT3334HD8’s firmware is also provided.

Appendix A ASCII Conversion Chart

Appendix B Dial Pulses and Tones

Appendix C Result Code Summary

Appendix D S-Register Summary

Appendix E AT Command Summary

Appendix F Remote Configuration

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MT3334HD8 User Guide

Technical Specifications

Model Number

MT3334HD8

Data Rates (Modem) Eight independent modems (Modem A, B, C, D, E, F, G, H), each operating at

33,600, 31,200, 28,800, 26,400, 24,000, 21,600, 19,200, 16,800, 14,400, 12,000,

9600, 4800, 2400, 1200, or 0-300 bps

Data Rates (Fax)

14,400, 9600, 4800, and 2400 bps

Data Format

(Modem)

Serial, binary, asynchronous at all data rates

Configuration

Each of the card’s modems is independently configurable

Compatibility (Modem) ITU-T V.42bis, V.42, V.34plus, V.34, ITU-T V.32bis, V.32, V.25bis, V.21,

V.22bis, V.22, V.23, V.17, Bell 212A* and 103/113*

Compatibility (Fax) ITU-T Group 3, T.4, T.30, V.21, V.27ter, V.29, V.17, and EIA TR29.2

Error Correction

Data Compression

Speed Conversion

ITU-T V.42 (MNP® Classes 3 and 4, and LAP-M)

ITU-T V.42bis (4:1 throughput) or MNP 5 (2:1 throughput)

Serial port data rates adjustable to 300, 1200, 2400, 4800,9600, 19,200, 38,400,

57,600, and 115,200 bps

Flow Control

XON/XOFF, CTS/RTS, ENQ/ACK

Mode of Operation

Half or full duplex over dial-up lines; automatic or manual dialing, automatic

or manual answer

Intelligent Features Fully AT command compatible; auto dial; redial; repeat dial*; dial linking*;

pulse or tone dial; dial pauses; call status display; auto-parity and data rate

selection; keyboard-controlled modem options; nonvolatile memory; on-

screen displays of modem parameters, stored telephone numbers, and help

menus; and remote configuration.

AT Commands

100% compatible with standard AT command set

60 characters

Command Buffer

Automatic Dialing

Standard AT command asynchronous dialing

Modem Modulations FSK at 300 bps, PSK at 1200 bps, QAM at 2400, 4800, and 9600 bps (non-

trellis), QAM with trellis-coded modulation (TCM) at 9600, 12,000, 14,400,

16,800, 19,200, 21,600, 24,000, 26,400, 28,800, 31,200, and 33,600 bps

Fax Modulations

V.21 CH2 FSK at 300 bps

V.27ter DPSK at 4800 and 2400 bps

V.29 QAM at 9600 and 7200 bps

V.17TCM at 14400, 12000, 9600, and 7200 bps

Carrier Frequencies 1600, 1646, 1680, 1800, 1829, 1867, 1920, 1959, 2000 Hz

ITU-T V.34

Carrier Frequencies: Transmit originate:

V.22bis/V.22 or Transmit answer:

Bell 212A Standard Receive originate:

1200 Hz

2400 Hz

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Introduction

(2400 & 1200 bps)

Receive answer:

1200 Hz

Carrier Frequencies: Transmit originate:

Bell 103/113

1270 Hz mark

1070 Hz space

2225 Hz mark

2025 Hz space

2225 Hz mark

2025 Hz space

1270 Hz mark

1070 Hz space

(300 bps)

Receive originate:

Transmit answer:

Receive answer:

Carrier Frequencies: Transmit originate:

V.21

980 Hz mark

1180 Hz space

1650 Hz mark

1850 Hz space

1650 Hz mark

1850 Hz space

980 Hz mark

1180 Hz space

Receive originate:

Transmit answer:

Receive answer:

Carrier Frequencies: Transmit originate:

V.23

390 Hz mark

450 Hz space

1300 Hz mark

2100 Hz space

1300 Hz mark

2100 Hz space

390 Hz mark

450 Hz space

Receive originate:

Transmit answer:

Receive answer:

Fax Modulations

V.21Ch2 FSK at 300 bps

V.27ter DPSK at 4800 and 2400 bps

V.29 QAM at 9600 and 7200 bps

V.17 TCM at 14400, 12000, 9600, and 7200 bps

Fax Carrier

V.21 CH2 (half duplex)

Frequencies

1650 Hz mark, 1850 Hz space for transmit originate

1650 Hz mark, 1850 Hz space for transmit answer

V.27ter: 1800 Hz Originate/Answer

V.29 QAM: 1700 Hz Originate/Answer

V.17 TCM: 1800 Hz Originate/Answer

Transmit Level

-13 dBm

Frequency Stability +0.01%

Receiver Sensitivity -43 dBm under worst case conditions

AGC Dynamic Range 43 dB

Serial Interface

Diagnostics

EIA RS-232C

Power-on self-test; ITU-T V.54 local analog loop, local digital loop, remote

digital loop.

Firmware Upgrades Flash memory; available on Multi-Tech’s BBS

Indicators

LEDs for Carrier Detect and Off Hook/Out-Of-Service

Environmental

Temperature range: 0°–50° C (32°–120° F)

Humidity range: 20–90% (noncondensing)

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MT3334HD8 User Guide

Power

Requirements

5 VDC at 0.95 A

16 VDC at 0.1 A

Power Consumption Approximately 6 watts

Dimensions

Weight

23.3 × 2.3 × 29.2 cm (9.2 × 0.9 × 11.5 in.) H × W × D

1.1Kg (2.5 lb.)

Limited Warranty

Fuses

Two years

F1 (+5 V), F2 (-16 V), F3 (+16 V)

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2 Installation

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MT3334HD8 User Guide

Introduction

This chapter describes how to install the MT3334HD8 modem card into a CommPlete Communication

Server CC9600 chassis. This equipment should be installed only by a qualified service person.

The MT3334HD8 assembly consists of a high-density modem card and a front panel. Figure 1 shows the

layout of the MT3334HD8 card. The MT3334HD8 assembly plugs into power and data, Ethernet, and T1

bus connectors on the inside of the CC9600 chassis. There are no external connectors.

Connectors

LEDs

Figure 1. MT3334HD8 modem card.

Safety Warnings

✔ Never install telephone wiring during a lightning storm.

✔ Never install telephone jacks in wet locations unless the jacks are specifically designed for wet

locations.

✔ Never touch uninsulated telephone wires or terminals unless the telephone line has been disconnected

at the network interface.

✔ Use caution when installing or modifying telephone lines.

✔ Avoid using a telephone (other than a cordless type) during an electrical storm. There may be a remote

risk of electrical shock from lightning.

✔ Do not use the telephone to report a gas leak in the vicinity of the leak

✔ Ports that are connected to other apparatus are defined as SELV. To ensure conformity to EN 41003,

ensure that these ports are only connected to the same type on the other apparatus.

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Installation

Pre-Installation Notes

Warning: Interconnection directly, or by way of other apparatus, of ports marked “SAFETY WARNING

see instructions for use” with ports marked or not so marked may produce hazardous conditions on the

network. Advice should be obtained from a competent engineer before such a connection is made.

•

All installation must be done by a qualified service person.

To reduce emissions, be sure to use blanking plates to cover empty slots in the CC9600 chassis.

Any other apparatus, including cable and wiring, connected between the MT3334HD8K modem and

the point of connection to any speech band circuit shall comply with the following:

1. The overall characteristics of this apparatus shall be such as to introduce no material effect upon

the electrical conditions presented to one another by the modem and he speech band circuit.

2. The apparatus shall comprise only

a. apparatus approved for the purpose of connection between the modem and a speech band

circuit; and

b. cable and wiring complying with a code of practice for the installation of equipment

covered by this part of BS 6328 or such other requirements as may be applicable.

Note: Such apparatus may have been approved subject to limitations in its use.

Installation Procedure

1. Unpack the MT3334HD8 assembly from its packaging and save the packaging for possible future

use. Perform a visual inspection of the MT3334HD8. If you are concerned about its condition, call

Technical Support for instructions.

2. Turn off both PS9600 power supplies.

3. The MT3334HD8 must be installed in a segment in which a RASCard with a T1 module is installed.

Remove a blank device panel or previous MT3334HD8 card from that segment.

4. Supporting the MT3334HD8 by the front panel and the bottom edge of the card, place it into the

CC9600’s open device slot. Make sure the edges of the MT3334HD8 card mate properly with the

guides of the device slot.

5. Slide the MT3334HD8 into the CC9600 chassis until you feel the MT3334HD8’s connectors mate with

the CC9600’s bus connectors.

6. Tighten the MT3334HD8’s retaining screws.

7. Turn on the PS9600 power supplies.

8. Note the PS9600 LED indicators. If they are not lit, see Chapter 5. If they are lit, proceed with

MultiModemManager operation (Chapter 4 of the MultiModemManager Owner’s Manual).

Note: A self-test runs each time the CommPlete Communications Server is turned on. Refer to Chapter 5

of the MultiModemManager Owner’s manual for more details on the power-on self-test.

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3 AT Commands

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MT3334HD8 User Guide

Working with AT Commands

The MT3334HD8’s modems are controlled by instructions called AT commands, so called because the

attention characters AT precede each command or command string (sequence of commands). You can

send commands to the modem from your keyboard while in terminal mode, or you can use communi-

cations software to issue these commands automatically.

A MT3334HD8 modem is in command mode when it is not dialing or online. When it is in command

mode, you have access to a complete communications system that allows you to use several features,

including the basic AT command set described in this chapter. Using the basic AT command set, you can

enter phone numbers for automatic dialing, configure modem options, and monitor telephone activity. In

addition, you can command your modem to perform advanced features such as error correction, data

compression, speed conversion, and more.

This chapter describes the MT3334HD8’s operational modes, and shows you how to use each of the

MT3334HD8’s AT commands. MT3334HD8 commands and responses are compatible with all systems and

with all data communications software using the AT command set.

For easy reference, the MT3334HD8 has a help command that provides you with short, on-screen

descriptions of the modem commands. The help command is explained later in this chapter.

Modes of Operation

The MT3334HD8 operates in two basic functional modes: command mode and online mode. (There is also

an in-between state, wait-for-carrier, in which the modem is out of command mode but not yet online.)

When you power up the modem, it is in command mode, and is ready to accept and respond to commands

from your keyboard or software.

An MT3334HD8 modem enters online mode after it dials, connects with another modem, and detects a

valid carrier signal. If it does not detect a carrier signal within the time frame controlled by register S7, the

modem abandons the call and re-enters command mode.

You can make the modem enter online mode without dialing by typing either the D command or the A

command.

The modem exits online mode if the carrier signal is lost or intentionally dropped. When this happens, the

modem hangs up and re-enters command mode.

By sending certain “escape” characters to the modem while online, you can make it enter command mode

without losing the carrier signal.

For auto answer-only applications, you can disable a modem’s ability to recognize AT commands by using

the %DC1 command. When you do this, the MT3334HD8 ignores all commands, and functions as a non-

intelligent modem. The %DC1 command and other MT3334HD8 commands are explained later in this

chapter.

Command Structure

You can control a wide variety of modem operations and options when the modem is in command mode.

AT commands tell the modem to dial a number, to answer a call, to operate at a certain speed, to use a

certain compression technique, and many other functions. AT commands consist of one or two letters,

which may be preceded by an ampersand (&), a dollar character ($), a pound character (#), a percent

character (%), or a greater-than character (>). The Q command, for example, determines whether the

modem returns result codes, while the &QcommandselectswhichATcommandsetthemodemuses.

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AT Commands

A parameter after a command (0, 1, 2, etc.) tells the modem which option to use. If you do not specify a

parameter, the modem assumes the 0 (zero) option. E, for example, is the same as E0. You can issue

several commands on a single line (a command string) as long as the line does not exceed 60 characters.

Note that though Q1 is one command, it counts as two characters in the command line.

Each command has a valid range of parameters; for instance, &W can have only 0 or 1 as a parameter.

Valid commands generate an OK result code. A few generate an additional response, such as a list of

parameters. An invalid command, such as &W3, which has a parameter outside the valid range, generates

an ERROR result code. Most commands have a default parameter, one that is enabled when the modem is

turned on or reset with the ATZ or AT&F command. Factory defaults are stored in read-only memory

(ROM), and cannot be changed. User-defined defaults can be stored in nonvolatile random-access

memory (NVRAM), and can be changed or deleted at will.

Command Editing

Always begin a command with the letters AT. You may type the command in upper case or lower case, but

not both. The AT command is not executed until you press the ENTER key. Use the BACKSPACE key to erase

the previous command character; it will not erase the AT characters once they are typed. If your keyboard

has no BACKSPACE key, use CTRL+H. You can change the character recognized by the modem as BACKSPACE

to any other ASCII character by changing register S5.

To cancel an entire command that has been typed but not yet executed, press CTRL+X. This also clears the

command buffer. The effect is the same as backspacing the command, only quicker.

The MT3334HD8 stores characters entered in a command in the modem’s command buffer until they are

executed by pressing ENTER. The command buffer’s capacity is 60 characters. The attention characters

(AT) do not count in the 60 allowed command characters. You may use spaces for increased readability

when typing a command; they are neither stored in the command buffer nor counted in the 60 allowed

characters. Hyphens, parentheses, etc., are not allowed.

If you exceed the 60-character limit or type invalid characters, the command buffer is automatically erased

and an ERROR message is displayed. You must then retype the command within the 60-character limit,

using only the allowed characters.

The commands in this chapter are organized by function. A brief summary follows.

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MT3334HD8 User Guide

Table 1. AT Commands by Function

Topic

Dialing Action

Command

Description

Dial

Continuous redial

On-hook/off-hook

Page

Dial Modifiers

Pulse dialing

Tone dialing

Wait for new dial tone

Reverse originate/answer mode

Dialing pause

Continuous redial

;

Return to command mode after dialing

Flash on-hook

Quiet answer

Call card tone detect

Phone Number

Memory

D...N

N...N

Store a phone number

Dial a stored number

Number linking

List stored telephone numbers

Configuration

Storage & Recall

Store configuration

Load default configuration

Reset modem

Modem Responses

(Result Codes)

Echo command mode characters

Result codes: enable/disable

Result codes: Multi-Tech or standard

Result codes: verbose/terse

Result codes and call progress

Answerback

Online Connection

Auto speed detection

Answer tone

%DC

&CD

>DT

&RD

Command mode control

Cleardown at disconnect

DTMF detection

Fallback modes when online

Guard tones

Busy-Out After Disconnect

Pulse dial ratios

Square wave ring detect

Calling tones

Trellis-coded modulation

Long space disconnect

V.34 Controls

&RA

Echo canceler frequency offset comp.

Asymmetric bit rate

RS-232 Interface

Controls

Carrier Detect control

Data Terminal Ready control

Clear to Send control

&RF

&SF

Data Set Ready control

CTS/RTS interaction control

DSR/CD interaction control

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AT Commands

Error Correction &

Data Compression

&E0

&E1

&E2

&E14

&E15

Non-error correction mode

Auto-reliable mode

Reliable mode

Data compression disabled

Data compression enabled

V.42 error correction modes

V.42 error correction at 300 bps

Auto-reliable buffering

Auto-reliable fallback character enable

Retransmit count

Speed Controls

$BA

$MB

$SB

Baud adjust

Modem baud rate

Serial port baud rate

Immediate Action

&RN

&RR

Repeat last command

Inquire product code

List current operating parameters

List S-register values

List current operating parameters

List online diagnostics

Rate renegotiation

Retrain

Flow Control

&BS

$EB

&E3

&E4

&E5

&E6

&E7

&E8

&E9

&E10

&E11

&E12

&E13

Maximum reliable block size

Asynchronous word length (10/11-bit)

Flow control disabled

Hardware flow control

XON/XOFF flow control

XON/XOFF no pass-through

XON/XOFF pass-through

Hewlett Packard ENQ/ACK pacing off

Hewlett Packard ENQ/ACK pacing on

Non-error correction mode flow control off

Non-error correction mode flow control on

Pacing off

Pacing on

Number of XOFF characters sent

Escape

+++AT<CR>

Default in-band escape sequence

Sequences

<BREAK>AT<CR> Alternate out-of-band escape sequence

Escape sequence selection

Force answer mode

Go back online

Remote

Configuration

%%%AT<CR> Remote configuration escape sequence

Change login password

Change setup password

Line Probes

%DP

%DF

&RP

L10

L11

Read line probe data

Format line probe data

Immediate line probe

Display signal strength

Display signal to noise ratio

Display noise strength

Diagnostics

Respond to remote digital loopback signal

Loopback test modes

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MT3334HD8 User Guide

Dialing Commands

Dialing commands are used to dial and to hang up.

Dial

s = phone number

Default: none

The letter D in a command causes the modem to dial the telephone number immediately following it. For

example, if you type ATD5551212<CR>, the modem dials the number 555-1212.

The MT3334HD8 supports several dialing methods. With the D command, you can specify either pulse

(ATDP) or tone (ATDT) dialing. You can also modify the dialing command with several characters that

are explained in “Dial Modifier Commands” in this chapter.

The MT3334HD8 lets you select either smart (wait-for-dial-tone) dialing or blind dialing. With smart

dialing, the modem waits for and detects dial tones and busy signals. With blind dialing, the modem works

with timed pauses (determined by the value of register S6), not dial tone and busy signal detection. See the

X command for more information on blind and smart dialing.

Continuous Redial

If you select smart dialing through the X3 or X4 command, the A: command lets you continuously redial a

busy number until your call is answered. (North American units have a maximum of 10 redials; this

command is not available on UK or International models.)

Use this command only if you have reached a busy number after executing a normal dial command. Type

A: (you need not type AT, nor do you need to press ENTER), and the modem redials the number. If you

again reach a busy signal, the modem continues to redial until it gets through. You can stop the modem

from redialing by pressing any key.

To save a step when redialing a phone number, enter a colon (:) at the end of the phone number. The result

is the same as if you had entered A:

On-Hook/Off-Hook

n = 0 or 1

Default: none

You can make the modem go on-hook (hang up) or go off-hook with the H command.

H0 (or H) hangs up the modem

H1 brings the line off-hook, just as if you had picked up the telephone handset.

It is not necessary to use the H1 command to bring the line off-hook when using the D command. The

modem automatically goes off-hook when you press ENTER at the end of the dial command.

Dial Modifier Commands

The dial string can include the digits 0 through 9, the pound sign (#), the asterisk (*), and the letters A, B,

C, or D. The latter are used by some PBXs; the exact function will depend on the PBX manufacturer’s

feature set and implementation. There are also several command characters, called “dial modifiers,” that

can be included within a dialing command after the letter D. Their functions include pulse or tone dialing,

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AT Commands

pauses in the dial sequence, automatic redials if a number is busy, and reverting to command mode or

switching to answer mode after dialing.

P, T Pulse or Tone Dialing

Default: P

The MT3334HD8’s modems can dial numbers by using pulse dialing, tone dialing, or a combination of

both methods. Pulse dialing, used by rotary-dial telephones, uses the timed opening and closing of a relay

to encode the numbers. Tone dialing, used by push-button (touch-tone) telephones, uses dual tone

multifrequency (DTMF) dialing.

P selects pulse dialing.

T selects tone dialing.

Insert P or T in the dialing command just before the digits you want to pulse- or tone-dial.

For example, to pulse-dial the number 555-1212, type ATDP5551212 and press ENTER. To tone-dial the

same number, type ATDT5551212 and press ENTER. If neither pulse nor tone dialing is specified in the

dial command, the modem uses whatever method was used last.

Immediately after the modem has been turned on or reset, it uses pulse dialing, even if you do not include

P in your dial command.

As an example of combining pulse and tone dialing, assume you are calling out of a PBX (switchboard)

system where a 9 has to be pulse-dialed, then the rest of the number has to be tone-dialed after pausing for

a second dial tone. To dial this example, type ATDP9,T5551212 and press ENTER. (The comma causes a

pause.)

Wait for New Dial Tone

Inserting W into the dialing command causes the modem to wait for another dial tone before it resumes

dialing. (It is not necessary to enter W at the beginning of the dialing command.)

Because the modem must be able to detect the dial tone for this command to work, you also

must select wait-for-dial-tone dialing with the X2 or X4 command.

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MT3334HD8 User Guide

Reverse Originate/Answer Mode

n = 0 or 1

Default: R0

The R command lets you reverse the modem’s mode of operation from originate to answer, or from

answer to originate; for example, if you need the modem to answer the phone but then go into originate

mode.

R (with no number) at the end of the dialing string reverses in originate mode.

R0 disables mode reversing.

R1 enables mode reversing when R is added to the dial string.

Dialing Pause

Enter a comma in the dialing string to make the modem pause while dialing. This pause lasts two seconds

(North American models) or four seconds (U.K. and International models) for each comma entered. You

can force longer pauses by entering multiple commas, or you can change the length of the pause caused by

a comma by setting register S8 to any value from 0 through 255 seconds (North American models), 4 through

7 seconds (U.K. models) or 4 through 255 seconds (International models).

Each comma in a dialing command counts as one of the 60 allowed characters.

;

Continuous Redial

Enter a colon (:) as the last character of a dialing command to cause the modem to continuously redial the

number, if it detects a busy signal, until the call is answered. North American models are limited to 10

redials. You must select smart dialing (X3 or X4) for this to work. (Not available in U.K. or International

models.)

Note: This command has largely been superseded by software-based continuous redial features.

Return to Command Mode After Dialing

Enter a semicolon (;) as the last character of a dialing command to cause the modem to return to

command mode immediately after executing the command instead of waiting for a carrier signal and

going online.

For example, type ATDT5551212; to tone-dial the number and immediately go back into command mode.

The semicolon is useful when modem data transfer is not desired, as in voice communications, or in

applications using touch tones as a data entry method, such as bank-by-phone.

Flash On-Hook

Some switchboard systems react to a momentary on-hook condition. Insert an exclamation mark into the

dialing command to cause the modem to “flash” on-hook for half a second, just as if you had pressed the

switch hook on a telephone set for half a second. (With U.K. models, the exclamation mark causes the

modem to flash on-hook for 90 milliseconds.)

For example, to flash on-hook to transfer to extension 5678 after dialing the number 555-1234, type

ATDT5551234,,!5678. The commas cause a 4-second pause.

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AT Commands

Quiet Answer

Use the @ command to access a system that does not provide a dial tone. The @ command causes the

modem to wait before processing the next character in the dialing string. The wait is for one or more rings

back followed by five seconds of silence.

For example, ATDT5551212@6313550 causes the modem to dial the first number (555-1212), then wait

for the time specified in register S7 for at least one ringback and five seconds of silence. If the modem

detects a busy signal, it hangs up and generates a BUSY result code. If it does not detect five seconds of

silence, it hangs up and generates a NO ANSWER result code. If it does detect five seconds of silence, it

dials the second number (631-3550).

Call Card Tone Detect

Use the $ command to dial services that require you to enter your call card number after a tone. A $

character in the dialing string causes the modem to pause and wait for an AT&T call card “bong” or a 1600

Hz tone (prevalent in the U.K.). When the modem detects the tone, it processes the rest of the dialing

string. If it does not detect a tone within the time set by register S7 (a 45-second default), the modem

aborts with a NO CARRIER message. Pressing any key also aborts the $ command.

In the following example, the $ command is placed between an access/phone number and the caller’s

credit card number:

ATDT1028806127853500$123456789

Phone Number Memory Commands

The modem can store up to two telephone numbers in nonvolatile memory. You can store the numbers

with the DsNd command, dial them with the Nd command, link them so that one will be automatically

dialed after the other with the NdNe command, or list them with the L command.

DsNd Store a Phone Number

s = phone number d = 0 or 1

Default: none

You can store a telephone number command string of up to 60 characters in the modem’s phone number

memory. You can store two of these 60-character strings using the DsNd command. The memory

locations are labeled N0 and N1.

Store a command line by typing it as you would any other command, appending the appropriate Nd

memory location.

For example, the tone-dialed number 1-612-555-1212 is stored at memory location N0 by typing

ATDT16125551212N0 and pressing ENTER. The number is not dialed with this store command.

After storing a number, check to see that it has been stored correctly by typing ATL and pressing Enter.

When you store a phone number, you store the entire command string, so you can effectively create a

macro for each number. For example, if you know a particular number needs to have extended result

codes, detect busy or dial tone, error correction,XON/XOFFflowcontrol,pacing,anddatacompressionenabled, the

command to store the entire command stringatlocationN0isATX4&E1&E5&E13&E15DT16125551212N0.

Dial a Stored Number

d = 0 or 1

Default: none

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MT3334HD8 User Guide

You can automatically dial a telephone number that is stored in the modem’s number memory by typing

ATNn, where n = 0 or 1. For example, you can dial a number stored at N0 by typing ATN0 in terminal

mode and pressing ENTER.

Warning: Do not include the letter D in this command, or the stored number will be erased.

NdNe Number Linking

d = 0 or 1 e = 1 or 0

Default: none

Number linking allows the modem to dial a second stored number if the first stored number is busy. (See

the DsNd command.) This command is useful when a computer can be accessed through more than one

phone number. However, it cannot be used with blind dialing, since busy signals would not be detected.

To link the number in memory location N0 to the number in N1, type ATN0N1 and press Enter. You can

cycle back and forth between two numbers by linking them several times in one command:

ATN0N1N0N1N0N1<CR>. The only limit on the number of times the modem can cycle between two

numbersisthe60-charactermaximumallowedinacommandline.

List Stored Telephone Numbers

Use the L command to display dialing commands stored in the modem’s nonvolatile memory. Typing

ATL<CR> displays the stored N numbers in the following format:

T14082345678

P9,T14089876543

All digits and command letters are displayed. The N number is shown first, followed by the complete

dialing command and telephone number as originally entered.

Configuration Storage and Recall Commands

The MT3334HD8 stores parameters in two places. It stores factory default parameters in read-only

memory (ROM), and customized parameters in nonvolatile random access memory (NVRAM). You can-

not change the default parameters in ROM; however, you can change parameters in temporary memory

and then store them in NVRAM as custom settings. You can then recall the custom settings as if they were

factory default settings.

&Wn Store Configuration

n = 0 or 1

Default: &W1

The &W command stores current AT commands and S-register values in nonvolatile memory, so you

won’t lose your custom settings when you turn off the modem or reset it.

&W0 (or &W) stores all current AT command and S-register values in nonvolatile random access memory

(NVRAM) and configures the modem so that it reads your custom settings in NVRAM when the modem is

turned on or when it is reset with the Z command. (The &F reset command will continue to read the

factory default settings in ROM unless you store the &F9 command.)

&W1 erases your custom settings in NVRAM when the modem is turned off or reset, causing the modem to

read the factory default settings in ROM when it is subsequently turned on or reset.

For further information on how the &W command interacts with the reset commands, see Table 2.

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AT Commands

&Fn Load Default Configuration

n = 0, 8, or 9

Default: &F8

MT3334HD8 modems store factory default AT command settings and S-register values in read-only

memory (ROM); they store your custom AT command and S-register values in nonvolatile random access

memory (NVRAM).

The &F0 (or &F) command resets the modem to the factory default values stored in ROM or to your

custom values stored in NVRAM, depending on whether you last stored an &F8 or an &F9 command.

When &F8 is stored and an &F command is issued, the modem reads the factory default settings stored in

ROM.

When &F9 is stored and an &F command is issued, the &W setting determines whether the modem reads

settings stored in NVRAM or ROM. If the modem is set to &W0, it reads your custom settings stored in

NVRAM. If the modem is set to &W1, it erases your stored settings (including the &F9 command) and

reads the factory default settings stored in ROM. Many communications programs issue the &F command

automatically—the &F9 command allows you to select your own defaults.

Note that for either an &F8 or an &F9 command to be effective after a reset it must be stored using the

&W0 command.

Table 2 summarizes how the &F and Z reset commands interact with the &W command; note that the &F

reset command operates differently from the Z reset command:

Table 2. Where the Modem Reads Configuration Parameters

Previous Command

AT&W1 (default)

AT&W0

AT&F

ROM

Power-On and ATZ

ROM

NVRAM

AT&F8&W0

ROM

NVRAM

AT&F9&W0

NVRAM

Reset Modem

The Z command resets the modem to its default configuration and clears the command buffer. The result

is the same as turning the modem off and on. When you type ATZ, the state of the &W command

determines where the default values originate. &W0 defaults come from the customized configuration in

NVRAM, and &W1 defaults come from the factory default configuration in ROM. Because Z clears the

command buffer, it must be the last command in a command string; normally it is issued by itself: ATZ.

Note that the Z reset command operates differently from the &F reset command. See Table 2 on page 21.

Modem Response (Result Code) Commands

The MT3334HD8’s modems can give responses to commands. The most common one is OK, but the

modems also can alert you or your software to dial tones, busy signals, connection speeds, and whether the

connection is made with error correction or compression enabled. These responses are called result codes,

and they can be terse or verbose, Multi-Tech or standard, basic or extended.

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Echo Command Mode Characters

n = 0 or 1

Default: E1

Normally, when you type commands on the keyboard, the modem echoes the characters back to the

computer or terminal, which displays them on the monitor. Use the E command to turn this feature off

and on.

E0 disables the echo.

E1 enables the echo.

Result Codes Enable/Disable

n = 0, 1, or 2

Default: Q0

You can use the Q command to enable or disable result codes for applications such as computer-controlled

auto dialing. You can also use it to disable responses and echo in answer mode while leaving originate

mode still intelligent; this is called the no response answer mode of operation.

Q0 (or Q) enables result codes.

Q1 disables result codes for applications such as computer-controlled auto-dialing.

Q2 enables the no response answer mode, which leaves originate mode intelligent while turning off answer

mode responses and echo.

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AT Commands

&Qn Result Codes (Multi-Tech or Standard AT)

n = 0 or 1

Default: &Q0

The MT3334HD8 gives you a choice between Multi-Tech result codes and standard AT command set

responses. Multi-Tech result codes give you more information, but some datacomm programs may not be

able to use them, in which case, select the standard result codes.

&Q0 selects Multi-Tech responses with RELIABLE, LAPM, and COMPRESSED modifiers. With &Q0,

the verbose result code for 14,400 bps is CONNECT 14400 LAPM COMPRESSED.

&Q1 selects AT responses with no RELIABLE, LAPM, or COMPRESSED modifiers. With &Q1, the

verbose result code for 14,400 bps is CONNECT 14400.

Result Codes (Verbose/Terse)

n = 0 or 1

Default: V1

The V command controls whether the modem’s result codes display as verbal (“verbose”) or digital

(“terse”) messages. For example, if no carrier signal is detected after dialing, the result can be displayed

either as NO CARRIER, or as the digit 3.

V0 (or V) displays the modem’s result codes as digits.

V1 displays result codes as words.

Result Codes and Call Progress Selection

n = 0–4

Default: X0

The X command selects which result codes the modem provides in command mode and whether the

modem uses “smart dialing” or “blind dialing”. When it smart dials, the modem listens for dial tones and

busy signals and responds to them. When it blind dials, the modem ignores the signals and relies on

timing instead.

X0 causes the modem to blind dial. Instead of looking for a dial tone, it pauses for the time set in register

S6 and then dials regardless. Once a connection has been made, it sends the Bell 103 basic code

CONNECT to the terminal. It ignores any busy signals.

X1 causes the modem to blind dial, but in addition to the basic CONNECT code it provides extended

codes consisting of the word CONNECT and the speed of the connection: CONNECT 2400,

CONNECT 4800, CONNECT 9600, CONNECT 14400, CONNECT 19200, CONNECT

28800, and so forth. In this mode, the modem does not recognize or respond to dial tones or busy

signals.

X2 causes the modem to wait for a dial tone before dialing. If it does not detect a dial tone within the time

set by S6, the modem sends a NO DIALTONE result code to the terminal. In this mode, the modem pro-

vides extended result codes, but does not respond to busy signals.

X3 causes the modem to blind dial, but also it looks for a busy signal, and if it detects one, it sends a BUSY

result code to the terminal. In this mode, the modem provides extended result codes, but it does not

respond to dial tones.

X4 causes the modem to look for a dial tone and a busy signal, and respond with NO DIALTONE or

BUSY, as appropriate. It also provides extended result codes. It is the most useful setting for most

datacomm programs.

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&An Answerback

n = 0 or 1

Default: &A0

The &A command controls the MT3334HD8’s answerback feature. Answerbacks are used in some online

realty applications and elsewhere as a security measure. The &A command enables a modem to return a

message to an identification request from another computer. The default identification is MESSAGE

NOT PROGRAMMED.

&A0 disables the answerback feature.

&A1 enables the modem to return a message to an inquiry.

Online Connection Commands

The following commands control the conditions of the online connection.

#An Auto Speed Detection

n = 0–3

Default: #A0

An MT3334HD8 modem can operate as a 33,600 bps, 28,800 bps, 19,200 bps, 14,400 bps, 9600 bps, 4800

bps, 2400 bps, or 300 bps modem. Use the #A command to select the speed that the modem uses for initial

handshaking and subsequent speed selection. The #A command does not control the originating rate of the

modem (that is done by the modem baud rate command $MB), but only the answer mode starting speed.

#A0 causes the modem to start at maximum speed, with fallback to 31,200 to 28,800 to 26,400 to 24,000 to

21,600 to 19,200 to 16,800 to 14,400 to 12,000 to 9600 to 4800 to 2400 to 1200 to 300 bps.

#A1 causes the modem to operate at maximum speed only.

#A2 causes the modem to start at maximum speed, with decremental fallback to 4800 bps.

#A3 causes the modem to start at 2400 bps in V.22bis mode, with fallback to 1200 to 300 bps.

Answer Tone

n = 0 or 1

Default: B0

The B command selects the frequency the modem uses for its answer tone. (The answer tone is the tone a

modem receiving a call transmits to the modem that called it, thus initiating the handshake between the

two modems.) At higher speeds (2400 to 33,600 bps) there is no conflict, because all protocols use the Bell

frequency of 2225 Hz. However, the ITU-T specification for V.22 has an answer tone frequency of 2100 Hz.

This command is available only in International models.

B0 enables ITU-T frequencies including V.21 (300 bps) and V.23 (1200/75 bps).

B1 enables Bell frequencies including Bell 103 (300 bps).

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AT Commands

%DCn AT Command Control

n = 0 or 1

Default: %DC0

The %DC command allows you to disable the modem’s ability to respond to AT commands. It can be used

with auto answer applications in which no call origination is required, with some UNIX applications, and

with other applications that require you to disable the modem’s command mode.

%DC0 enables command mode.

%DC1 disables command mode.

Note: If you save %DC1 as part of your default configuration, you can re-enable command mode by typing

AT%DC0 and pressing ENTER in the first ten seconds after you power up the modem.

&CDn Cleardown at Disconnect

n = 0 or 1

Default: &CD0

In the V.32, V.32bis, and V.34 protocols, a cleardown is sent by one of the modems to signal the other

modem that it is going to hang up. A cleardown is rate renegotiation in which the modem that is hanging

up tells the other modem that it has no speeds that it can connect at. It is designed to help the remote

modem detect a hang-up. However, it does take a second or two to send the cleardown. If you find this

delay unacceptable, you can disable cleardown by using the &CD command.

&CD0 enables cleardown at disconnect.

&CD1 disables cleardown at disconnect.

>DTn DTMF Detection

n = 0 or 1

Default: >DT0

Normally, when it goes off-hook, a fax modem ignores tones from the other end of the connection unless

they are fax or modem handshake tones, in which case it responds in kind. The >DT1 command causes

the modem to report DTMF (touch-tone) tones and fax calling tones to software for further processing. A

typical use would be for a program that routes calls to specific communications applications depending on

the type of call or upon a DTMF tone added to a dialing string.

>DT0 disables DTMF detection.

>DT1 enables DTMF detection when the modem goes off-hook.

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#Fn Fallback Modes

n = 0, 1, or 2

Default: #F2

The #F command controls whether the modem will fall back to a lower speed because of an unacceptable

error rate. If line conditions deteriorate, the modem has the ability to fall back from its original speed to

the next lower speed when operating in V.34, V.32bis, or V.32 mode. If the error rate becomes too great,

the modem performs a retrain at the next lower speed. If, after the retrain, the error rate is still too high,

the modem performs a retrain at the next lower speed, down to 4800 bps.

If the modem returns online at the original speed after the first retrain, the modem starts a counter and a

timer. If three retrains occur within a two-minute period, the modem falls back to 4800 bps.

The fallback and fall-forward speeds for the modem are 33.6K, 31.2K, 28.8K, 26.4K, 24.0K, 21.6K, 19.2K,

16.8K, 14.4K, 12K, 9.6K, and 4.8K bps.

#F0 (or #F) disables fallback when online.

#F1 lets the modem fall back from the starting speed to a low speed of 4800 bps in 2400 bps decrements.

#F2 lets the modem fall back when line conditions deteriorate, but also lets it fall forward in 2400 bps

increments if line conditions improve.

&Gn Guard Tones

n = 0, 1, or 2

Default: &G0 (models outside U.K.) or &G2 (U.K. models only)

The &G command is used to control the presence or absence of guard tones from the transmitter when in

answer mode at either 1200 or 2400 bps. Guard tones are used in Europe and other areas to allow the

modem to function in the telephone systems. Guard tones are not used in the United States. U.K. models

are locked at &G2 (1800 Hz guard tone).

&G0 disables ITU-T guard tones.

&G1 enables ITU-T 550 Hz guard tone.

&G2 enables ITU-T 1800 Hz guard tone.

*Hn

Busy-Out After Disconnect

n = 0 or 1

Default: *H0

The *H1 command causes the MT3334HD8 to remain out of service and return a busy signal until

configuration from the CommPlete Communication Server’s dedicated management console has finished.

If no configuration option is set on the dedicated management console, the MT2834MR remains out of

service for ten seconds after disconnect. Register S94 controls the length of the out-of-service, or busy-out,

time (see Chapter 4).

*H0 disables busy-out after disconnect.

*H1 enables busy-out after disconnect.

&Pn Set Pulse-Dial Ratios

n = 0 or 1

Default: &P0 (Models outside U.K.) or &P1 (U.K. models only)

The &P command sets the time ratios between the open (break) and closed (make) states of dialing pulses.

U.K. models are locked to &P1 (67:33 ratio). See Appendix B for more dial pulse information.

&P0 sets a pulse dial ratio of 60 ms break to 40 ms make.

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AT Commands

&P1 sets a pulse dial ratio of 67 ms break to 33 ms make.

&RDn Square Wave Ring Detect

n = 0 or 1

Default: &RD0 (U.K. and International models)

&RD1 (North American models)

The ring back sound that you hear when you dial a number is generated at the local telephone office or

PBX. Normally, it is a sine wave analog tone. However, some PBXs generate square wave rings that can go

undetected by normal ring detection circuits, resulting in a failure to make a connection. To enable your

modem to detect square wave rings, use the &RD1 command.

&RD0 enables sine wave ring detection only.

&RD1 enables sine wave and square wave ring detection.

$Tn Calling Tone

n = 0 or 1

Default: $T1

The $T command enables or disables the modem’s calling tone, which is required by some European

countries to identify the caller as a modem.

$T0 enables the calling tone.

$T1 disables the calling tone.

#Tn Trellis-Coded Modulation

n = 0 or 1

Default: #T1

The #T command enables or disables trellis-coded modulation (TCM) on the modem. There is usually no

need to disable TCM, except for an unusual line condition called impulse noise.

#T0 disables TCM.

#T1 enables TCM.

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Long Space Disconnect

n = 0 or 1

Default: Y0

When two modems are connected in reliable mode, a link disconnect request packet is sent to request a

disconnect. In non-error correction mode, there is no “polite” way to request a disconnect. As a result,

some “garbage” may be received when a hang-up command is issued.

Y0 disables the modem’s use of the break signal.

Y1 enables the modem’s use of the break signal, which shuts off the modem’s receiver and disconnects

(both modems must have Y1 enabled).

V.34 Commands

The following commands apply only in V.34 mode.

%Fn Echo Canceler Frequency Offset Compensation

n = 0 or 1

Default: %F0

The %F command enables and disables echo canceler frequency offset compensation which, when

enabled, can decrease modem performance.

%F0 disables echo canceler frequency offset compensation.

%F1 enables echo canceler frequency offset compensation.

&RAn Asymmetric Bit Rate

n = 0 or 1

Default: &RA0

The &RA command enables or disables asymmetric bit rate operation in V.34 mode. The asymmetric bit

rate feature lets the modem transmit at one rate while receiving at a different rate.

&RA0 enables asymmetric bit rate operation.

&RA1 disables asymmetric bit rate operation.

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AT Commands

RS-232 Interface Commands

These commands define how an MT3334HD8 modem will use and respond to standard RS-232 signals.

&Cn Carrier Detect Control

n = 0, 1, 2, or 4

Default: &C1

The &C command lets you control the Carrier Detect (CD) signal on the RS-232/V.24 interface. Normally,

CD goes high when the modem detects a carrier on the communications link, and drops when it loses the

carrier. By using &C, however, you can force the signal to stay high, or to drop momentarily when the

remote modem disconnects. (This option is useful with some CBX phone systems and mainframe front

ends, which require CD to act in this manner.) You can also force the modem to reset when the CD signal

drops.

&C0 forces CD high.

&C1 allows CD to act normally—to go high when the modem detects a carrier, and to drop when it loses

the carrier.

&C2 causes CD to drop for one second on disconnect, and then go high again. (If you want to set the drop

time to something other than one second, change register S24.)

&C4 resets the modem when CD drops.

&Dn Data Terminal Ready Control

n = 0, 1, 2, or 3

Default: &D2

The Data Terminal Ready (DTR) signal on pin 20 of the RS-232/V.24 interface must be high, or “on,” in

order for the modem to operate. A high DTR signal tells the modem that the computer it is connected to is

ready to communicate through the modem.

The DTR signal can also be used to cause the modem to reset to its default parameters, as if you had given

the modem an ATZ command.

&D0 (or &D) causes the modem to ignore DTR.

&D1 causes the modem to hang up when DTR drops. While DTR is low, the modem accepts commands,

but will not dial or auto-answer until DTR goes high again.

&D2 acts the same as &D1.

&D3 causes the modem to reset when DTR drops . It will also hang up if it is online.

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&Rn Clear to Send Control

n = 0, 1, or 2

Default: &R1

The &R command lets you control the state of the Clear to Send (CTS) signal on pin 5 of the RS-232/V.24

interface. Normally, CTS follows RTS when the modem is online. You have three choices. You can force the

signal high, allow it to act normally, or set it to stay high until the modem disconnects, go low

momentarily, and then go high again. The last option is useful with CBX phone systems and mainframe

front ends that require CTS to act in this manner.

&R0 lets CTS act normally, that is, to follow RTS.

&R1 forces CTS high. When the modem goes online, CTS still provides flow control.

&R2 lets CTS drop on disconnect for the time set by register S24, then go high again.

&Sn Data Set Ready Control

n = 0, 1, or 2

Default: &S1

Use the &S command to control the state of the Data Set Ready (DSR) signal on the RS-232/V.24 interface.

Normally, DSR follows CD. You can force the signal high; allow it to act normally; or set it to stay high until

the modem disconnects, go low momentarily, and then go high again.

&S0 forces DSR high.

&S1 allows DSR to act normally, that is, to follow CD.

&S2 sets up DSR so that it drops for one second on disconnect and then comes up again. (If you want to set

the drop time to something other than one second, change register S24.)

&RFn CTS/RTS Interaction Control

n = 0 or 1

Default: &RF1

In normal operation, Clear to Send (CTS) follows Request to Send (RTS) when the modem is online. In

other words, if RTS goes off, CTS goes off. In some applications, however, it is necessary for CTS to operate

independently of RTS.

&RF0 enables CTS to follow RTS.

&RF1 enables CTS to operate independently of the state of RTS. See the &R command for control of CTS.

&SFn DSR/CD Interaction Control

n = 0 or 1

Default: &SF0

Normally, the Data Set Ready (DSR) signal follows the Carrier Detect (CD) signal. In other words, if CD

goes high, DSR goes high. In some applications, however, it may be necessary for DSR to operate

independently of CD.

&SF0 enables DSR to follow CD.

&SF1 enables DSR to operate independently of CD. For control of DSR, see the &S command.

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AT Commands

Error Correction and Data Compression Commands

You can configure a modem to any of three different V.42 modes of operation (each mode can be with or

without compression). They are the non-error correction, auto-reliable, and reliable modes. You can also

turn data compression on or off.

&En Error Correction Modes

n = 0, 1, or 2

Default: &E1

Select the modem’s error correction mode using the &E0, &E1, or &E2 command.

&E0 disables the modem’s V.42 error correction capabilities, and the modem functions as a non-error

correction modem.

&E1 enables auto-reliable mode. During the handshaking procedures at the start of the online connection,

the modem queries whether the other modem is using V.42 error correction. If the modem determines

that the other modem is using V.42, it switches itself into reliable (V.42) mode and enables error

correction. If it determines that the other modem is not using V.42, the modem remains in non-error

correction mode.

&E2 enables reliable mode, in which the modem uses its V.42 error correction capabilities for all

transmissions. In reliable mode, the modem must be connected to a modem with a V.42 protocol (MNP or

LAP-M).

The V.42 standard includes MNP Class 3 and 4 and LAP-M error correction methods. The V.42 mode select

command (#L) selects which type of error correction the modem uses for transmissions.

&En Data Compression

n = 14 or 15

Default: &E15

Data compression is normally enabled, providing &E1 (auto-reliable mode) or &E2 (reliable mode) has

also been selected. However, you may wish to turn it off in certain circumstances.

&E14 disables data compression.

&E15 enables data compression.

#Ln V.42 Error Correction Modes

n = 0–3

Default: #L0

The #L command selects the V.42 error correction method (MNP or LAP-M) the modem uses when

originating a call. In answer mode, the modem ignores the #L command and accepts whichever V.42

mode, MNP or LAP-M, the originating modem offers.

#L0 causes the modem to negotiate the V.42 error correction method with the answering modem, and to

begin negotiation with LAP-M. If both modems have LAP-M capability, the modems will use LAP-M

mode. If one or both modems do not have LAP-M capability and both have MNP, the modems will use

MNP.

#L1 enables MNP error correction and disables LAP-M.

#L2 enables LAP-M error correction and disables MNP.

#L3 enables LAP-M error correction and disables MNP, but skips the V.42 detection phase used by the

other commands. Both modems must be set with #L3.

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$En V.42 Error Correction at 300 bps

n = 0 or 1

Default: $E0

At 300 bps, error correction is not normally used.

$E0 disables 300 bps/V.42 error correction altogether.

$E1 enables the modem to function at 300 bps in non-error correction (&E0), auto-reliable (&E1), or

reliable (&E2) mode.

$An Auto-Reliable Buffering

n = 0 or 1

Default: $A0

In auto-reliable mode, the modem has four seconds to establish a reliable connection, after which the

modem drops to non-error correction mode. Any data received during this period will normally be

discarded. The $A command causes the modem to buffer (store) data that is received during the auto-

reliable time-out period. This data is then output by the modem after the CONNECT message.

$A0 discards the data received during the auto-reliable time-out period.

$A1 buffers data received during the auto-reliable time-out period.

$Fn Auto-Reliable Fallback Character Enable/Disable

n = 0 or 1

Default: $F0

In auto-reliable mode, the modem has four seconds to establish a reliable connection. If a single carriage

return is received from the remote modem during this period, the auto-reliable modem assumes that the

remote modem is not in reliable mode, and drops to non-error correction mode. The carriage return is the

only character that causes the modem to drop to non-error correction mode. Any other data is either

buffered or discarded.

Use the $F command to enable this feature.

You can use the auto-reliable fallback character ($F) and auto-reliable buffering ($A) commands together

to cause the modem to buffer all data received up until the carriage return, and then drop to non-error

correction mode. All data received is then output following the CONNECT message.

$F0 causes the modem not to fall back to non-error correction connect if a carriage return is received.

$F1 causes the modem to fall back to non-error correction connect if a carriage return is received.

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AT Commands

$Rn Retransmit Count

n = 0 or 1

Default: $R0

If errors are received during a reliable connection, the modem re-sends the block of data that contained an

error. If another error occurs, it re-sends the block again. The modem counts the number of times that a

data block is re-sent.

$R0 causes the modem to disconnect if the same block of data is re-sent 12 times without being received

properly, on the assumption that the line is unsuitable for transmission.

$R1 causes the modem to disable the retransmit counter, so that the modem keeps trying to send data and

will not abort, no matter how many times the same block is resent. Type AT$R0 to disconnect the modem

if all attempts to re-send the block fail.

Speed Conversion Commands

Speed conversion allows the MT3334HD8 to communicate at a fixed speed through the serial port while

communicating at an independent speed over the online communications link.

Speed conversion is necessary for data compression, since data compression requires data to be sent from

the computer to the modem at a rate up to four times faster than the modem’s transmission speed.

Speed conversion is also useful for an auto answer modem connected to a computer that does not have auto

baud capability, since the computer must be set at a fixed baud rate regardless of the speed at which the

modem communicates over the phone line.

$BAn Baud Adjust

n = 0 or 1

Default: $BA0

Even though the term “baud adjust” sounds like it should mean the same thing as “speed conversion,” it

actually means the opposite. Turning baud adjust off turns speed conversion on; turning baud adjust on

turns speed conversion off.

When baud adjust is on, the modem matches its RS-232 serial port speed to any changes in the computer’s

serial port speed in originate mode, or to the speed of the originating modem when it’s in answer mode.

With baud adjust on, the speed at which the modem communicates over the phone line is always the same

as the speed at which it communicates via its RS-232 serial port.

When speed conversion is on, the modem does not adjust its speed at the serial port to match its

transmission speed. Serial port speed and transmission speed can therefore be set independently. Speed

conversion is necessary for a high speed modem that is connected to a limited speed serial port.

$BA0 turns baud adjust off and speed conversion on.

$BA1 turns baud adjust on and speed conversion off.

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$MBn Modem Baud Rate

n = speed in bits per second

Default: $MB33600

The $MB command sets a modem’s initial transmission speed for originate mode. In V.32 mode (9600

bps), it also sets the transmission speed for answer mode. With speed conversion on, this transmission

speed can be different from the serial port speed.

When the modem answers a call from another modem, it automatically switches its transmission speed to

match the calling modem. However, if the MT3334HD8 originates a call to another modem that is unable

to connect at the transmission speed of the MT3334HD8, the MT3334HD8 will automatically drop to a

lower speed in an attempt to match the speed of the other modem.

For example, if the MT3334HD8 is set for 14,400 bps and calls another modem that has a top speed of 2400

bps, it will drop to 2400 bps.

$MB75

ITU-T V.23 mode

300 bps

1200 bps

2400 bps

4800 bps

$MB300

$MB1200

$MB2400

$MB4800

$MB7200

$MB9600

7200 bps

9600 bps

$MB12000 12,000 bps

$MB14400 14,400 bps

$MB16800 16,800 bps

$MB19200 19,200 bps

$MB28800 28,800 bps

$MB33600 33,600 bps (factory default)

Speed conversion must be on for this command to work. If baud adjust is on ($BA1), speed conversion is

off and a modem baud rate command will be ignored.

The S48 register also can affect maximum transmission speed. See Chapter 4.

$SBn Serial Port Baud Rate

n = speed

Default: $SB57600

The $SB command sets the speed of the MT3334HD8’s serial port in both originate and answer modes.

Speed conversion allows you to set this serial port baud rate at a fixed speed of up to 115,200 bps, regardless

of the modem’s transmission speed setting.

For this command to work, the modem’s baud adjust feature must first be turned off with the $BA0

command. When baud adjust is on, as soon as the modem receives its first AT command, it automatically

adjusts its serial port baud rate to match the speed of the computer or terminal to which it is connected.

However, in applications such as automatic answer, the modem may not receive AT commands. In this

case it is helpful to be able to preset the serial port baud rate with the $SB command.

In addition to setting the modem’s serial port speed, this command sets the speed at which the modem

issues command mode responses (result codes).

The MT3334HD8 accepts AT commands at any speed, regardless of the speed preset by the $SB command.

If the modem receives a command at a speed different from the preset speed, the modem switches its

serial port baud rate to match the new command speed, even though the baud rate value stored by the $SB

command remains the same. This provides you with a convenient way to switch the serial port speed while

still making it easy to automatically return to the original speed the next time the modem is powered up or

reset.

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AT Commands

$SB300

300 bps

$SB1200

$SB2400

$SB4800

$SB9600

$SB19200

$SB38400

$SB57600

1200 bps

2400 bps

4800 bps

9600 bps

19,200 bps

38,400 bps

57,600 bps

$SB115200 115,200 bps (factory default)

Immediate Action Commands

Use these commands to get information about AT commands and the current settings of the modem. For

additional immediate action commands, see “Line Probe Commands” on page 41.

Repeat Last Command

Default: None

Type A/ to repeat the previous command. Do not precede this command with AT or press ENTER to

execute it.

Inquire Product Code

n = 0, 1, or 2

Default: none

Some systems or software packages automatically check the identification of the modem by using the I

command. Besides using it to check the modem ID, you can use the I command to check the version

number of the modem’s built-in software, known as firmware.

ATI0 or ATI requests the modem’s ID number.

ATI1 requests the modem’s firmware version number. You can use this command to identify your

modem’s firmware level when calling Technical Support.

ATI2 requests the product name, such as MT3334HD8.

ATI5 requests the digital signal processor version number.

L5, L7 List Current Operating Parameters

Default: none

The L5 and L7 commands cause your modem to list its current operating parameters. These lists are

useful when you are changing communications software, or when you are changing modem default

settings. All modem configuration parameters are listed.

ATL5 lists the modem’s current operating parameters.

ATL7 lists additional modem parameters.

List Current S-Register Values

Default: none

ATL6 lists the current values in the modem’s S-registers. This information can be very useful if you wish

to change S-registervalues.

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List Online Diagnostics

Default: none

The L8 command displays the modem’s online status. You can print this display and use it as a modem

status report or as diagnostic information (such as when calling Technical Support).

If you type +++ATL8 with the modem online, the current online status will be displayed. If you type

ATL8 with the modem in command mode, the most recent online status will be displayed. If you type

ATL8 immediately after modem power-up, the message NO INFORMATION AVAILABLE will be

displayed.

To enter this command while online, type +++ATL8<CR>. Your modem’s online status will be

displayed, listing current operating conditions such as link type, line speed, serial speed, line quality, and

reason for last disconnect.

&RN Rate Renegotiation

Default: none

The &RN command forces the modem to perform a rate renegotiation while online. To issue it, you must

first escape to command mode by issuing the +++AT<CR> command.

&RR Retrain

Default: None

The &RR command forces the modem to perform an immediate retrain while online. To issue it, you must

first escape to command mode by issuing the +++AT<CR> command.

Flow Control Commands

Flow control refers to the techniques used by data terminal equipment and the MT3334HD8 to pause and

resume the flow of information between them. It prevents a device from accepting more data than it can

handle. The MT3334HD8 implements flow control in both directions. When the MT3334HD8 halts the

flow of data, it is called flow control, and when the computer halts the flow, it is called pacing.

&BSn Maximum Reliable Block Size

n = 0 or 1

Default: &BS1

When the modem is in reliable mode, use the &BS command to set the maximum size of a data block.

MNP Class 3 sends a 64-character block, while Classes 4 and 5 normally send blocks of 256 characters or

less. Reducing the block size for MNP 4 and 5 may improve overall throughput when phone lines are noisy;

however, it also could slow data transfer if line quality is good.

&BS0 sets the maximum transmit block size to 64 characters.

&BS1 sets the maximum transmit block size to 256 characters.

$EBn Asynchronous Word Length

n = 0 or 1

Default: $EB0

The MT3334HD8 can operate with either a 10-bit format (one start bit, seven data bits, one parity bit, and

one stop bit) or an 11-bit format (one start bit, eight data bits, one parity bit, and one stop bit) in both

command and online modes.

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AT Commands

$EB0 enables a 10-bit format It automatically detects parity when an AT command is issued.

$EB1 enables an 11-bit format.

&E3 Flow Control Disable

The &E3 command completely disables data flow control initiated by the modem.

&E4 Hardware Flow Control

Factory default. The &E4 command enables the modem’s use of the Clear to Send (CTS) signal on the RS-

232/V.24 interface to regulate data flow. When CTS drops, data flow is suspended until the signal goes high

again. This method of flow control works in conjunction with pacing (i.e., computer-initiated flow

control), which uses the Request to Send (RTS) signal on the RS-232/V.24 interface. Hardware flow control

cannot be enabled unless an active error correction protocol is selected.

&E5 XON/XOFF Flow Control

XON/XOFF flow control is an in-band method of data flow regulation used by the modem or computer

(i.e., by flow control or pacing). If you issue the &E5 command to the modem, it will respond to

XON/XOFF pacing, and use XON/XOFF characters as its own method of flow control to the computer.

In-band data regulation means that the XON and XOFF characters (^Q and ^S, respectively) are inserted

into the stream of data rather than using separate control lines. When an XOFF character is detected, the

data stream is suspended until an XON character is detected. The drawback to using this method of pacing

is that some files may contain these characters. If such a file is transferred using a modem, the file transfer

can be suspended indefinitely.

&En XON/XOFF Pass-Through

n = 6 or 7

Default: &E6

When XON/XOFF pacing is active, the local modem has two options regarding the XON and XOFF

characters. It can respond to and discard the characters from the computer, or it can respond to the

characters and pass them through the datacomm link to the remote modem, thereby pacing the remote

modem as well.

&E6 causes the modem to respond to and discard the XON and XOFF characters.

&E7 causes the modem to respond to the characters and pass them through the data link to the receiving

modem.

&En Hewlett Packard ENQ/ACK Pacing

n = 8 or 9

Default: &E8

If the MT3334HD8 is used with Hewlett Packard (or compatible) equipment, it can be configured to

respond to ENQ/ACK pacing as a complement to any other form of active flow control or pacing. In that

case, pacing from the Hewlett Packard equipment is processed according to the HP protocol.

&E8 causes the modem to ignore ENQ/ACK pacing.

&E9 causes the modem to respond to the ENQ (^E) and ACK (^F) characters.

&En Non-Error Correction Mode Flow Control

n = 10 or 11

Default: &E10

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When two modems are connected in non-error correction mode, XON/XOFF flow control can be used as a

complement to XON/ XOFF pacing.

&E10 disables non-error correction mode flow control.

&E11 enables non-error correction mode flow control.

&En Pacing (Computer-Initiated Flow Control)

n = 12 or 13

Default: &E13

Pacing is the means by which the DTE (data terminal equipment—your computer or terminal) regulates

the stream of incoming data. It is only enabled when the modem has some form of flow control active,

such as RTS/CTS or XON/XOFF. When pacing is enabled, the modem responds to the DTE’s pacing signals.

When pacing is disabled, the modem ignores any pacing signals from the DTE.

&E12 disables pacing.

&E13 enables pacing.

#Xn Number of XOFF Characters Sent

n = 0 or 1

Default: #X0

The #X command allows the modem to send either a single or multiple XOFF characters when the

modem’s buffer becomes full. When the buffer is full, the next character received causes an XOFF charac-

ter to be sent. In default mode, only one character is sent until the buffer reaches the XON level; however, it

is also possible to send one XOFF character for every character received after the buffer is full.

#X0 causes only a single XOFF character to be sent after the buffer is full.

#X1 causes one XOFF character to be sent for every character received after the buffer is full.

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AT Commands

Escape Sequences

Escape sequences are also known as escape codes. They are used to cause the modem to enter command

mode from online mode without disconnecting the call. There are two local escape sequences used by the

modem, +++AT<CR> and <BREAK>AT<CR>, and one remote escape sequence, %%%AT<CR> (see

“Remote Configuration.”).

+++AT<CR> In-Band Escape Sequence

If the modem is online with a remote modem, you can cause the modem to enter command mode, without

disconnecting the call, by typing an escape code. The default escape code used by the modem is three plus

signs (+++) followed by the letters AT, up to 10 command characters (most typically H, to hang up), and

ENTER. The modem then escapes to command mode, executes the command (if any), and remains in

command mode. For example, to hang up the modem at the end of a call, type +++ATH <CR>.

<BREAK>AT<CR> Out-of-Band Escape Sequence

The MT3334HD8 provides an alternate escape method that uses a break signal as the escape code. The

break signal— ten or more zero bits issued by data communications software—allows the DTE to signal

the modem without the risk of the modem interpreting data characters as modem control characters. The

break signal is followed by the letters AT, up to 60 command characters, and ENTER. When this sequence is

used, the modem executes the command and immediately returns to online mode, unless the command is

to hang up and/or reset the modem (an H or Z command). In the latter case, the modem escapes to

command mode after executing the H or Z command.

%En Escape Sequence Options

n = 0–5

Defaults: %E1 and %E4

The default setting is for the modem to respond to the +++ escape method. Optional settings are for the

modem to respond to the <BREAK> method, for the modem to respond to either the +++ or the

<BREAK> methods, and for the modem to ignore both methods and not escape. The %E command is

used to select these options as follows:

%E0

%E1

%E2

%E3

%E4

%E5

Modem won’t escape

+++ AT<CR> escape method (factory default).

<BREAK> escape method.

Either +++ or <BREAK> escape methods.

Disables OK response to +++ (factory default).

Enables OK response to +++.

%E1 %E5 Enables +++ method and OK responses to +++.

%E3 %E5 Enables +++ or <BREAK> method and OK responses to +++.

Force Answer Mode

You can use the A command to force the modem into answer mode. Type ATA when in command mode

to immediately bring your modem off-hook, out of command mode, and into online answer mode, and to

cause it to transmit its carrier signal over the phone line. If no responding carrier tone is received by your

modem within forty-five seconds (or by the time you have specified in register S7), your modem stops

transmitting its tone, hangs up, and goes back into command mode.

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Go Back Online

You can use the O command to bring the modem out of command mode and back into online mode. The

O command reverses the result of entering the escape code. The O command brings the modem into

whichever online mode (originate or answer) that it was in prior to entering command mode.

Remote Configuration Commands

When you are online with another Multi-Tech modem, you can issue AT commands to it by sending a

remote configuration escape sequence. The remote modem responds by displaying a menu and asking for a

setup password. The MT3334HD8 has two default passwords. Please note that if you change them, you

cannot retrieve them by resetting the modem by using AT&W1; you must know the new passwords to

make any further changes. For further information on remote configuration, see Appendix F, “Remote

Configuration.”

%%%AT<CR> Remote Configuration Escape Sequence

Enter the remote configuration escape sequence to initiate remote configuration when you are online with

another Multi-Tech modem. The default escape sequence used by the MT3334HD8 is three percent signs

(%%%) followed by the letters AT and ENTER. The remote configuration escape character, which is stored

in register S13, can be changed either locally or remotely for greater security.

#Ixxxxxx Change Login Password

xxxxxx = password

Default: #IMULTI-TECH

Use the #I command to enter or change the remote configuration login password.

AT#Ixxxxxx enters the current remote configuration login password, where xxxxxx represents the

password. If the password is wrong, the remote modem responds with ERROR; if it is correct, the remote

modem responds with OK, and you can proceed with the #S command.

AT#I=xxxxxx stores a new remote configuration login password, where xxxxxx represents the password.

The password is case sensitive, and can be any combination of upper and lower case keyboard characters.

It must be six to ten characters in length.

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AT Commands

#Syyyyyy Change Setup Password

yyyyyy = password

Default: #SMODEMSETUP

Use the #S command to enter or change the remote configuration setup password. Before you can use it,

you must enter the login password using the #I command.

AT#Syyyyyy enters the current remote configuration password, where yyyyyy represents the password. If

the password is wrong, the remote modem responds with ERROR; if it is correct, the remote modem

responds with OK, and you can proceed with the next command.

AT#S=yyyyyy stores a new remote configuration setup password, where yyyyyy represents the password.

The password is case sensitive, and can be any combination of upper and lower case keyboard characters.

It must be six to ten characters long.

Line Probe Commands

Before V.34 negotiation can take place, the local and the remote modem use modulated calling and

answering tones to exchange information about their capabilities. If they can communicate in V.34 mode,

they exchange probing signals to identify impairments in the telephone channel. Using the results of these

line probes, they then set the communication parameters, including carrier frequencies and data rates,

that they will use for the transmission. This process takes about five seconds. The following commands

apply to the MT3334HD8 modems only when they are in V.34 mode.

%DPn Read Line Probe Data

n = 0 or 1

Default: %DP0

Normally, the modem does not store data it acquires during the V.34 line probe. If you would like to

examine the line probe data using the L9, L10, or L11 commands, you must first use the %DP1 command

to instruct the modem to read and store the data.

%DP0 disables reading of line probe information during the handshake.

%DP1 enables reading of line probe information during the handshake.

%DFn Format Line Probe Data

n = 0 or 1

Default: %DF0

This command selects whether line probe data will be displayed as a graph with the Y axis showing signal

strength in dBm, or as a table with dBm values shown numerically. The graph format shows data in 150 Hz

increments from 150 Hz to 3750 Hz, whereas the table format shows data in 75 Hz increments from 150 Hz

to 3750 Hz.

%DF0 displays line probe data in graph format.

%DF1 displays line probe data in table format.

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&RP Immediate Line Probe

Default: none

This immediate action command initiates a retrain that makes the processor read line probe information

for display using the L9, L10, and L11 commands. It is valid only when online in V.34 mode. Before

issuing the command, you must escape to command mode while remaining online. To combine both

actions, use the following command string: +++AT&RP<CR>.

The modem will not read and store the line probe information from this retrain unless you first issue a

%DP1 command

Display Line Probe Data

n = 9–11

Default: none

These immediate action commands cause the modem to display line probe information when it is in V.34

mode. The line probe information must first be read and stored by the modem (see “Read Line Probe

Data”). Data format is controlled by the Format Line Probe Data command, %DF.

The display commands are valid only in online mode. To use them online, you must first escape to

command mode with +++AT<CR>. To return online, enter ATO.

ATL9 displays signal strength information.

ATL10 displays the signal to noise ratio (SNR).

ATL11 displays noise information.

Diagnostic Commands

The MT3334HD8 has two diagnostic commands and four diagnostic modes. The power-on self-test is

activated every time power is applied. The U command selects a loopback test, while the &T command

enables a modem to respond to a loopback test from another modem. See Chapter 5, “Testing the

MT3334HD8,” for a fuller discussion. Refer to the L8 command to see how to list the diagnostic online

status.

&Tn Respond to Remote Digital Loopback Signal

n = 4 or 5

Default: &T5

The &T command enables or disables the modem’s ability to recognize the remote digital loopback (RDL)

test signal. (See Chapter 5 for remote digital loopback test procedures.)

AT&T4 lets the modem respond to an RDL signal, and places it in digital loopback.

AT&T5 causes the modem to ignore the RDL signal.

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AT Commands

Loopback Test Modes

n = 0–3

Default: None

Loopback tests send data through the modem in such a way that it loops back to the terminal where it was

entered, testing all the circuits along the way. The U command selects from several loopback tests. See

Chapter 5, “Testing the MT3334HD8,” for more information.

ATU0 places the modem in originate mode for the local analog loopback test.

ATU1 places the modem in answer mode for the local analog loopback test.

ATU2 performs the remote digital loopback test.

ATU3 performs the local digital loopback test.

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4 S-Registers

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Introduction

This chapter describes the MT3334HD8’s S-registers, which are small regions of memory where modem

configuration information is stored. Whereas AT commands tell a modem what to do, S-registers tell the

modem how or when to do it. Each S-register has a name that consists of the letter S and a number (S0, S1,

S2, etc.), hence the term S-register. Use the Sr? command to read the value stored in an S-register, and the

Sr=n command to change it.

S-Registers

Number of Rings Until Modem Answers

Unit: 1 ring

Range: 0–255

Default: 1

S0 defines the number of rings the modem waits before answering an incoming call. The default value is

one ring, which causes the modem to answer the call immediately after the first ring. The maximum

number of rings that can be configured is 255. Setting the value to zero disables auto answer.

Ring Count

Unit: 1 ring

Range: 0–255

Default: 0

S1 counts the number of rings that have occurred. It is a “read” type of register and is seldom, if ever, used

in typical operation. Each time an incoming ring signal is detected, S1 increases its value by one, up to a

maximum of 255. If you set S1 to a value other than its default value of zero, or if the value is increasing

with rings, this new value remains stored in S1 for eight seconds after the last ring is counted, after which

the value reverts back to zero.

Escape Code Character

Unit: Decimal

Range: 0–127

Default: 43 (+)

S2 defines the escape code character by its decimal ASCII code. The default character is the plus (+) sign

(decimal 43). S2 may be set for any ASCII character. Setting an S2 value greater than 127 results in no

escape character, and therefore no means of entering command mode from online mode without breaking

the online connection, unless you use the BREAK method.

Note: If you change the S2 value, you must make corresponding changes in your data communications

software.

Return Character

Unit: Decimal

Range: 0–127

Default: 13 (^M)

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S-Registers

S3 defines the carriage return character by its decimal ASCII code. The default setting is the ^M character

(decimal 13), which is the code for the ENTER key on most keyboards. S3 may be set for any ASCII

character.

Note: If you change the S3 value, you must make corresponding changes in your data communications

software.

Line Feed Character

Unit: Decimal

Range: 0–127

Default: 10 (^J)

S4 defines the line feed character by its decimal ASCII code. The default setting is ^J (decimal 10), which is

the code for the line feed key on most keyboards that have such a key. S4 may be set for any ASCII

character.

Backspace Character

Unit: Decimal

Range: 0–127

Default: 8 (^H)

S5 defines the backspace character by its decimal ASCII code. The default setting is the ^H character

(decimal 8), which is the code for the BACKSPACE key on most keyboards. S5 may be set for any ASCII

character.

Note: If you change the S5 value, you must make corresponding changes in your data communications

software.

Wait Time for Dial Tone

Unit: 1 second

Range:2–255(North America), 4–255(International), 4–7(U.K.)

Default: 2 (North America), 4 (International and U.K.)

S6 defines the length of time the modem waits after the ENTER key is pressed before executing a dial

command. The default setting is two seconds for North America, four seconds elsewhere.

Time for Carrier (Abort Timer)

Unit: 1 second

Range: 1–255 (USA), 1–45 (Canada and International), or 1–55 (U.K.)

Default: 45 (North America and International) or 55 (U.K.)

S7 determines the abort timer delay time, which is the amount of time your modem will wait for a carrier

signal before it disconnects. The default value is 45 seconds, except the U.K. model, for which it is 55

seconds. This means that, after dialing, the modem waits for a carrier signal for up to 45 or 55 seconds and,

if none is detected, aborts the call. The maximum S7 value is 255 seconds for the USA model, 45 seconds

for Canadian and International models, and 55 seconds for the U.K. model.

Pause Time for Comma

Unit: 1 second

Range: 0–255 (North America), 4–255 (International), 4–7 (U.K.)

Default: 2 (North America), 4 (International and U.K.)

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S8 determines the length of the pause caused by a comma in a dialing command. The default setting is two

seconds for the North American model, and four seconds for the International and U.K. models. S8 may

be set for up to 255 seconds. S8 also defines the length of time the modem waits before retrying a call after

it detects a busy signal. Some computer systems need more than two seconds to reset, in which case you

should increase the value of S8.

Carrier Detect Response Time

Unit: 100 ms

Range: 1–255

Default: 6

S9 determines the time delay between when the modem first detects a valid incoming carrier signal and

when the modem turns on its Carrier Detect circuit. The default setting is 600 milliseconds (six units of

100 ms each). S9 may be set for up to 25.5 seconds.

S10 Carrier Loss Disconnect Delay Time

Unit: 100 ms

Range: 1–254, 255

Default: 7

S10 defines the length of time after a loss of carrier signal before the modem disconnects. The default

setting is 700 ms (seven units of 100 ms each). Maximum delay is 25.4 seconds (decimal 254). Setting the

S10 value to 255 causes the modem not to disconnect with loss of carrier.

S11 Tone Dialing Spacing and Duration

Unit: 1 ms

Range: 1–255 (USA) or 80–255 (Canada, U.K., International)

Default: 70 (USA) or 80 (Canada, U.K., International)

S11 sets the speed of tone dialing (spacing and tone duration times). The default value is 70 units for

domestic models and 80 units for Canadian and International models, where each unit is one ms. In other

words, for domestic modems, each tone is sustained for 70 ms followed by a 70 ms pause. The minimum

S11 value allowed by most telephone systems is 50 ms (50 units). Very few telephone systems can handle

anything faster than that. The maximum S11 value is 255 ms (255 units).

S13 Remote Configuration Escape Character

Unit: Decimal

Range: 0–127

Default: 37 (%)

S13 defines the remote configuration escape character by its decimal ASCII code. The S13 default is the

percent character (decimal 37). When you enter the S13-defined character three consecutive times from a

remote site, your modem responds with its remote configuration procedure. A value of 0 disables remote

configuration.

S17 Changing Break Time

Unit: 10 ms

Range: 1–255

Default: 25 (250 ms)

S17 defines the break time (space) the modem sends the DTE when it receives a break signal from a remote

modem. Break duration is adjustable in 10 millisecond increments. The default is set to 25, for a 250

millisecond break.

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S-Registers

S24 PBX/CBX Disconnect Drop Time for DSR/CTS/CD

Unit: 50 ms

Range: 0–255

Default: 20 (1 second)

Some PBX and CBX phone systems require the modem’s DSR, CTS, and/or CD signals to drop briefly when

calls are disconnected. The MT3334HD8’s &R, &S, and &C commands can cause the modem to drop these

signals for a specified time upon disconnect, and then bring the signals up again. S24 defines the length of

time that the signals drop. The default setting of 20 results in a one-second drop time, which is what most

PBX/CBX systems with this requirement need.

S25 DTR Dropout Time

Unit: 100 ms

Range: 0, 1–255

Default: 0 (50 ms)

S25 sets the amount of time that DTR must be dropped before the modem disconnects. Typically, a

disconnect occurs when DTR is dropped for 50 milliseconds or more. This dropout time can be increased

up to a maximum of 25.5 seconds. The S25 unit value for zero is 50 ms. For values from 1 through 255, the

unit value is 100 ms.

S30 Inactivity Timer

Unit: 1 minute

Range: 0, 1–255 minutes

Default: 0 (disabled)

S30 can be used to cause the modem to disconnect if no data is transmitted or received for a specified

time. S30 runs during both reliable and non-error correction connections. The timer restarts any time a

data character passes through the serial port (either sent or received). If noise on the phone line causes an

error to be received during non-error correction mode, this also will restart the S30 timer. The factory

default of zero disables the timer.

S32 Time Lapse for Escape Sequence

Unit: 100 ms

Range: 0–255

Default: 20 (2 seconds)

S32 sets the time period to validate the escape sequence. If the S32 time interval expires before you press

ENTER, then the escape sequence is aborted. The default is two seconds.

S34 Command Buffer Length After Online Escape Sequence

Unit: Decimal

Range: 0–60

Default: 10

Sets the number of characters allowed in an AT command after an in-band online escape (+++ method).

If the number of characters after “AT” exceeds the S34 buffer length value, then the buffer is flushed and

the escape sequence is aborted.

S36 DTR Busy-Out Time

Unit: 1 second

Range: 0–255

Default: 0 (disabled)

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S36 sets the time between when DTR goes inactive and when the modem goes off-hook. The DTR busy-out

feature is disabled when S36 is set to 0.

Normally, when the DTR signal from the computer goes inactive, the modem goes on-hook after a time

that is set by S25. If S36 is set for a non-zero time, the modem then waits for the time set by S36; if DTR

has not gone active again in that time, the modem goes off-hook, causing a busy signal for callers. The

busy-out state ends when DTR goes active again.

S37 DTR Busy-In Time

Unit: 1 second

Range: 0–255

Default: 5

S37 sets the time between when DTR goes active and when the modem goes on-hook, if S36 has caused it

to go off-hook.

S43 Force V.34 Connect Speed

Unit: N/A

Range: 0, 33, 31, 28, 26, 24, 21, 19, 16, 14, 12, 96, or 48

Default: 0 (disabled)

S43 forces the modem to attempt to connect at a fixed speed in V.34 mode. The two-digit value

corresponds to the first two digits of the speed (S43=21 sets the connect speed to 21.6K bps, S43=96 sets

it to 9600 bps, etc.). The factory default of zero disables this feature and allows the modem to establish the

best speed for the conditions.

Note: The $MB command overrides S43 if the $MB command is set to a speed other than 33,600 bps.

S48 Maximum V.34 Connect Speed

Unit: N/A

Range: 0, 33, 31, 28, 26, 24, 21, 19, 16, 14, 12, 96, or 48

Default: 0 (disabled)

S48 sets the maximum speed in bps at which the modem can attempt to connect in V.34 mode. The two-

digit value corresponds to the first two digits of the speed (S48=26 sets the maximum connect speed to

26.4K bps, S48=48 sets it to 4800 bps, etc.). This register allows you to set lower speeds for line conditions

that will not support higher V.34 speeds such as 33.6K, 31.2K, 28K, 26.4K, or 24K. The factory default of

zero disables this feature and allows the modem to establish the best speed for the conditions (in effect, it

sets a maximum connection attempt of 33.6K).

S94 Out-of-Service Time

Unit: 1 second

Range: 0–254, 255

Default: 45

S94 sets the maximum number of seconds, from 0 through 254, that the modem remains out of service

when the *H1 command is active. A value of 255 causes the modem to remain out of service indefinitely.

However, if the modem receives an enable command from the management program while the modem is

out of service, the modem returns to service immediately, before the S94 time expires.

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S-Registers

Reading and Assigning S-Register Values

Use the S command to assign a value to an S-register and to read an S-register’s current value.

To read an S-register value, in terminal mode, type S, the S-register number, and a question mark (?), and

press ENTER. For example, to display the value of register S7, type ATS7? and press ENTER. The answer will

appear as a three-digit decimal number (e.g., 045).

To assign a new value to an S-register, type S, the S-register number, an equals sign (=), and a decimal

number. Convert all ASCII characters to their decimal equivalents before entering them. S-register decimal

values are 0–127 for ASCII characters, and 0–255 for numeric values. To make the change permanent, use

the &W0 command.

Examples of Assigning Values

1. Let’s assume you want to have longer pauses caused by the comma in a dial command: five seconds

instead of two. Type ATS8=5 to assign 5 as the value for register S8. The modem will now pause five

seconds for every comma in a dial command.

2. Or let’s assume that you wish to configure the modem to answer incoming calls after the thirtieth

ring instead of after the first ring. To configure register S0 with a value of 30, type ATS0=30 and

press ENTER.

3. Or let’s say you are calling long distance to another country code, and it is taking a long time to

connect. The register S7 (abort timer) factory default setting of 45 seconds is insufficient; the abort

timer times out and cancels the call before a connection is made. To change the S7 value to 55

seconds, type ATS7=55 and press ENTER. Now, after dialing, the modem allows 10 more seconds for

a carrier signal before aborting the call. The additional 10 seconds should provide enough time for

international calls.

Examples of Reading Values

1. To verify that you entered the value correctly in the preceding examples, type ATS8? and press

ENTER in the first example, ATS0? in the second example, and ATS2? in the third example. You

should receive the responses 005, 030, and 055, respectively.

2. When configuring S-registers, it is a good practice to include the verification read command in the

same command string as the configuration assignment command. In the three preceding examples,

type ATS8=5S8?, ATS0=30S3?, and ATS7=55S7?, respectively.

AT Commands that Affect S-Registers

For maximum throughput, the MT3334HD8’s default configuration is for originating a call to another

33,600 bps modem that supports error correction, data compression, and flow control. If the receiving

modem is not compatible, the MT3334HD8 can match any ITU-T or Bell standard modem (but not

proprietary protocols).

If you require a different configuration for your application, for example, if you want to use an

MT3334HD8 modem strictly as an auto answering device, or for service that does not support error

correction, you can selectively change the command parameters and S-register values in active memory and

save the new values by using the &W command.

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The &W0 (or &W) command stores all current AT command and S-register values into nonvolatile

random access memory (NVRAM) and configures the modem so that it reads your custom settings in

NVRAM when the modem is turned on or when it is reset with the Z command. (The &F reset command

will continue to read the factory default settings in read-only memory [ROM] unless you also store the

&F9 command. See Chapter 3.) For convenience, you can include the &W command in the same

command string that sets the new values in active memory, as in the following example:

AT&E2$SP1#L3$R0$MB19200$SB115200$EB1S0=10&W0<CR>

The &W1 command erases your custom settings in NVRAM the next time the modem is turned off or

reset, causing the modem to read the factory default settings in ROM when it is subsequently turned on or

reset.

For further information on how the &W command interacts with the reset commands, see Table 2 on page

21.

Before you use the &W command, check the modem’s current operating parameters by using the L5, L6,

and L7 commands.

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5 Testing the MT3334HD8

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Introduction

Each time you power up the MT3334HD8, it performs an automatic self-test to ensure proper operation.

The MT3334HD8 also has three diagnostic tests: local analog loopback, digital loopback

(remote/automatic), and digital loopback (local/manual). These ITU-T V.54 loopback tests isolate

telephone circuit and transmission problems.

In a loopback test, data from your computer loops through the circuits of your modem and/or a remote

modem before it appears on your monitor. When the loop has been completed, the data on your PC’s

monitor should match the original data.

The local analog loopback test allows you to verify that the modem’s transmitter and receiver circuits are

functioning properly.

The local digital loopback allows you to verify that the local computer or terminal, the two modems, and

the transmission line between them are functioning properly.

The remote digital loopback test allows you to verify that the remote computer or terminal, the remote

modem, the serial ports, the telephone line, and the local modem are functioning properly.

Note: All loopback tests operate at all speeds except 300 bps.

Other tests are initiated with the MultiModemManager software, as explained in the MultiModemManager

Owner's Manual.

Local Analog Loopback Test (V.54 Loop 3)

In this test, data from your computer or terminal is sent to your modem’s transmitter, converted into

analog form, looped back to the modem’s receiver, converted into digital form, and then sent to your

monitor for verification. No connection to the phone line is required. See Figure 2.

Computer or Terminal

Local MultiModem

Digital Analog

UUUUU

Type ATU0 or ATU1 in

terminal mode; hit ENTER.

Figure 2. Local analog loopback test.

Test procedure

1. Connect the modem to your computer. Using your communication software, set the desired baud

rate.

2. Type ATU or ATU0 and press ENTER. This places your modem in analog loopback mode in the

originate mode. A CONNECT message should appear on your display. The modem is now out of

command mode and in a pseudo-online mode.

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Testing the MT3334HD8

3. Note that the CD LED is on. If you’re set for 14,400 bps or higher, the Speed LED should be on. If the

CD LED is not on, there is a defect in your modem.

4. Enter characters from your keyboard. For this test, typing multiple uppercase U characters is a good

way to send an alternating test pattern of binary ones and zeros. The characters entered should be

displayed on your monitor. The TD and RD LEDs should flash when a character is entered.

5. For a more complete test, you should also test the modem in answer mode. To do this, you must first

terminate the originate mode by entering an escape sequence (+++AT<CR> or

<BREAK>AT<CR>). An OK should appear on your display. Then type ATU1 and press ENTER to

place the modem in analog loopback in answer mode.

6. Note that the CD LED is on. If you’re set for 14,400 bps or higher, the Speed LED should be on. If the

CD LED is not on, there is a defect in your modem.

7. Enter characters from your keyboard. Type multiple uppercase U characters to send an alternating

test pattern of binary ones and zeros. The characters entered should be displayed on your monitor.

The TD and RD LEDs should flash when a character is entered.

8. To exit the test, enter an escape sequence (+++AT<CR> or <BREAK>AT<CR>), which returns the

modem to command mode.

9. Your modem passes this test if the data received on your monitor are the same as the data entered

from your keyboard. If different data appear on your monitor, your modem is probably causing the

problem, though it could also be your computer. If your modem passes this test, but you are

receiving errors while on line, the remote modem or the phone line could be at fault.

Remote Digital Loopback Test (V.54 Loop 2)

In this test, your modem must be online with another modem, such as another ZDX, that is set up to

respond to a request for remote digital loopback. With the ZDX, this ability to respond is controlled by the

&T command. AT&T4 enables the response to remote digital loopback; AT&T5 disables the response. The

modem defaults to &T5 on power-up, so this must be changed on the remote modem before initiating

remote digital loopback.

Initiate remote digital loopback with the ATU2 command, which places the remote modem in digital

loopback mode. Data from your computer or terminal are transmitted through your modem and over the

phone line to the remote modem, where they are then looped back to your modem. See Figure 3.

Computer or Terminal Local MultiModem

Remote MultiModem Computer or Terminal

UUUUU

Digital Analog

Analog Digital

Type AT in terminal mode; hit

ENTER; dial remote modem;

establish online mode; enter

escape sequence; type ATU2

and hit ENTER

Figure 3. Remote digital loopback test.

Test procedure

1. Arrange to have &T4 set on the remote test modem.

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2. Open your communications software and go into terminal mode. Type AT and press ENTER; you

should get an OK message. Type AT&E0<CR> to disable error correction.

3. Dial the remote modem and establish your online connection.

4. Type the escape sequence (+++AT<CR> or <BREAK>AT<CR>) to bring your modem into

command mode while maintaining the connection with the remote modem.

5. Type ATU2 and press ENTER. The local modem responds to this command by transmitting an

unscrambled marking signal, which causes the remote modem to place itself in digital loopback

mode. Then the local modem exits command mode and enters online mode.

6. Enter data from your keyboard. For this test, typing multiple uppercase U characters is a good way

to send an alternating test pattern of binary ones and zeroes. Data received by the remote modem

enters its analog receiver, is converted to digital data, is reconverted into analog, and then is

transmitted back to your modem. Your modem passes this test if the data received on your monitor

is the same as the data entered from your keyboard.

7. To exit the test, enter an escape sequence (+++AT<CR> or <BREAK>AT<CR>), which returns

the modem to command mode. The modem should respond with an OK message. If you wish to stay

on line with the remote modem for normal data transmission, type ATO and press ENTER. If you

wish to terminate the call, type ATH and press ENTER to hang up.

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Testing the MT3334HD8

Local Digital Loopback Test (V.54 Loop 2)

This test is identical to the remote digital loopback test with one exception. Instead of using your modem

to signal a remote modem to place itself in digital loopback mode, your modem is placed in digital

loopback mode while the remote modem is not. Data is entered and transmitted from the remote modem,

sent across the phone line to the local modem, and looped back to the remote modem. See Figure 4.

Computer or Terminal Local MultiModem

Remote MultiModem Computer or Terminal

UUUUU

Digital Analog

Analog Digital

Type AT in terminal mode; hit

ENTER; dial remote modem;

establish online mode; enter

escape sequence; type ATU3

and hit ENTER

Figure 4. Local digital loopback test.

Test procedure

1. Open your communications software and go into terminal mode. Type AT and press ENTER; you

should get an OK message. Enter AT&E0<CR> to disable error correction.

2. Dial the remote modem and establish your online connection.

3. Type an escape sequence (+++AT<CR> or <BREAK>AT<CR>) to bring your modem into

command mode while still maintaining the connection with the remote modem.

4. Type ATU3 and press ENTER. Once you receive an OK message from your modem (if responses are

enabled), your modem is placed in digital loopback mode.

5. Have someone enter data from the remote keyboard. For this test, typing multiple uppercase U

characters is a good way to send an alternating test pattern of binary ones and zeros. The data

received by your modem enters its analog receiver, is converted to digital data, is reconverted into

analog, and then is transmitted back to the remote modem. Your modem passes this test if the data

received on the remote monitor is the same as the data entered from the remote keyboard.

6. To exit the test, enter an escape sequence (+++AT<CR> or <BREAK>AT<CR>), which returns

the modem to command mode. The modem should respond with an OK message. If you wish to stay

on line with the remote modem for normal data transmission, type ATO and press ENTER. If you

wish to terminate the call, type ATH and press ENTER to hang up.

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6 Warranty, Service, and

Technical Support

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Limited Warranty

Multi-Tech Systems, Inc. (“MTS”) warrants that this product will be free from defects in material or

workmanship for a period of two years from the date of purchase, or, if proof of purchase is not provided,

two years from date of shipment.

MTS MAKES NO OTHER WARRANTY, EXPRESSED OR IMPLIED,ANDALLIMPLIEDWARRANTIESOF

MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED.

This warranty does not apply to any products which have been damaged by lightning storms, water, or

power surges or which have been neglected, altered, abused, used for a purpose other than the one for

which they were manufactured, repaired by the customer or any party without MTS’s written

authorization, or used in any manner inconsistent with MTS’s instructions.

MTS’s entire obligation under this warranty shall be limited (at MTS’s option) to repair or replacement of

any products which prove to be defective within the warranty period, or, at MTS’s option, issuance of a

refund of the purchase price. Defective products must be returned by Customer to MTS’s factory,

transportation prepaid.

MTS WILL NOT BE LIABLE FOR CONSEQUENTIAL DAMAGES AND UNDER NO CIRCUMSTANCES

WILL ITS LIABILITY EXCEED THE PURCHASE PRICE FOR DEFECTIVE PRODUCTS.

Service

If your technical support specialist decides that service is required and you are outside the USA, your local

distributor of Multi-Tech products usually offers the quickest and most economical repair option. If

necessary, you may send your modem to our Mounds View factory in the USA. A modem that is shipped to

us from outside the USA must have a Returned Materials Authorization (RMA) and shipping instructions.

To return a modem for repair from inside the USA, no RMA is required; simply send it to us freight

prepaid. Include a description of the problem, return billing and shipping addresses, a check or purchase

order for out-of-warranty repairs, and, if possible the name of the technical support specialist you spoke

to.

If you need to inquire about the status of the returned product, be prepared to provide its serial number.

Please send modems that require repairs to the following address:

Multi-Tech Systems, Inc.

2205 Woodale Drive

Mounds View, MN 55112

Attn: Repair

If you are shipping from outside the USA, please contact our Repair Department for an RMA prior to your

shipment. You can contact us by telephone at +(612) 785-3500 or by fax at +(612) 785-9874.

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Warranty, Service, and Technical Support

Technical Support

Multi-Tech has an excellent staff of technical support personnel available to help you get the most out of

your Multi-Tech product. If you have any questions about the operation of this unit, please call (800) 972-

2439 (USA and Canada) or (612) 785-3500 (local and international). Please record MT3334HD8

information in the spaces provided below, and have it available when you call. If your MT3334HD8

requires service, the technical support specialist will guide you on how to send it in.

Recording Product Information

Please record the following information about your MT3334HD8 to help Technical Support answer your

questions. (The same information is requested on the Warranty Registration Card.)

Model no.:_____________________________________________________________________

Serial no.: _____________________________________________________________________

Firmware version: _______________________________________________________________

Driver version: _________________________________________________________________

MultiModemManager software name and version_________________________________________

RASExpress software version _______________________________________________________

Datacomm software name and version: ________________________________________________

FAX software version: ____________________________________________________________

Other software version: ___________________________________________________________

The modem model and serial numbers are silk-screened on your modem. The software versions are

printed on the diskette labels. Type ATI1<CR> in terminal mode to display the modem firmware version.

Please note the status of your modem in the space below before calling tech support. This includes LED

indicators, screen messages, diagnostic test results, problems with a specific application, etc.

____________________________________________________________________________

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MT3334HD8 User Guide

The Multi-Tech BBS

Multi-Tech maintains a bulletin board system (BBS) for its customers. Information available from the BBS

includes new product information, product upgrade data, and problem-solving tips. There is also a -

message service that lets you request additional information. The phone number for the Multi-Tech BBS is

(800) 392-2432 (USA and Canada) or (612) 785-3702 (local and international).

The BBS can be accessed by any asynchronous modem operating at 1200 bps to 33,600 bps at a setting of 8

bits, no parity, and 1 stop bit (8-N-1).

Logging onto the Multi-Tech BBS

To log on to the Multi-Tech BBS, perform the following steps:

1. Set your communications program to 8-N-1.

2. Dial our BBS at (800) 392-2432 (USA and Canada) or (612) 785-3702 (international and local).

3. At the prompts, type your first name, last name, and password; then press ENTER. If you are a first

time caller, the BBS will ask if your name is spelled correctly. If you answer yes, a questionnaire will

appear. You must complete the questionnaire to use the BBS on your first call.

4. Press ENTER until the Main Menu appears. From the Main Menu you have access to three main

areas: the Files Menu, the Message Menu, and Bulletins. For help on menu commands, type ?.

Downloading a File

If you know the file name

1. From the Main Menu, type F to access the Files Menu, then type D.

2. Enter the name of the file you wish to download from the BBS.

3. If a password is required, enter the password.

4. Answer Y or N to the automatic logoff question.

5. Select a file transfer protocol by typing the indicated letter, such as Z for Zmodem (the

recommended protocol).

6. If you select Zmodem, the transfer will begin automatically. If you select another protocol, you may

have to initiate the transfer yourself. (In most datacomm programs, the PAGE DOWN key initiates the

download.)

If you don’t know the file name

1. From the Main Menu, type F to access the Files Menu. For a list of file areas, type L twice. (If you do

not type the second L, you will list all of the files on the BBS.)

2. Mark the file areas you would like to examine by typing each file area’s list number and pressing

ENTER.

3. Enter L to list all the files in the selected file areas. Enter C to go forward in the file list and P to go

back.

4. Mark one or more files for download by entering M, the list numbers of the files, and pressing

ENTER.

5. Enter D. You will see a list of the files you have marked. Enter E if you would like to edit the list;

otherwise enter D again to start the download process.

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6. Select a file transfer protocol by typing the indicated letter, such as Z for Zmodem (the

recommended protocol).

7. If you select Zmodem, the file will transfer automatically. If you select another protocol, you may

have to initiate the transfer yourself. (In most communications programs, the PAGE DOWN key

initiates the download.)

8. When the download is complete, enter S to return to the File Menu.

Reading a Message

When you log on, the BBS will tell you if you have a personal message (mail). At the prompt Would

you like to read it now?, type R to read the message. This is the only point at which you

can read your mail, since you cannot read any messages from the Message Menu.

Leaving a Message

The Multi-Tech BBS has no public discussion area. To leave a personal message, select the Message Menu

by typing M at the Main Menu. Type E, then press ENTER to select the Sysop conference. Enter the name of

the recipient (or “Sysop”), the subject, and the message text. Press ESC to finish, then type S to save the

message and exit. To abort the message at any point, leave any of the fields blank and press ENTER.

Bulletins

When you log on, the BBS will ask if you would like to view the bulletin menu. The bulletins are menu-

driven; to read a bulletin, enter its number. You can also access the bulletins by typing B at the Main

Menu.

About CompuServe

In addition to the BBS, Multi-Tech provides support through CompuServe’s Modem Vendor Forum (GO

MODEMVEN) under GO MULTITECH. You can also download manuals, Help files, drivers, Microsoft Mail

scripts, and product tips and descriptions from the forum’s Multi-Tech library. Refer to your CompuServe

documentation for special operating procedures.

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About the Internet

Multi-Tech is a commercial provider on the Internet, and we retrieve e-mail messages from the following

mailboxes on a periodic basis:

[email protected]Technical Support

[email protected]

Marketing Dept.

[email protected]Sales Dept.

[email protected]

International Marketing & Sales

[email protected] Publications Dept.

Multi-Tech's presence includes a Web site at:

http://www.multitech.com

and an ftp site at:

ftp://ftp.multitech.com

The ftp server mirrors the Multi-Tech BBS.

About the Multi-Tech Fax-Back Service

Multi-Tech's fax-back service provides 24-hour access to sales, marketing, and technical literature for

customers in the USA. Dial (612) 717-5888, follow the voice prompts, and enter the document number for

either the Sales and Marketing catalog or the Technical Support catalog of documents. For convenience,

write your fax number in the following space: ___________________________________________.

From the Sales and Marketing catalog, you can request to have newsletters, white papers, press releases,

brochures, and other marketing literature faxed to you. From the Technical Support catalog, you can

request basic modem operation information and troubleshooting guides. With either catalog, simply enter

the FB Doc. number of the literature you wish to receive.

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Warranty, Service, and Technical Support

Upgrading the MT3334HD8 Firmware

The MT3334HD8’s firmware is contained in a flash PROM. At various times, Multi-Tech may add

enhancements and/or fixes to this firmware. The flash technology used in the MT3334HD8 allows these

upgrades to be loaded directly into the PROM chip through the modem’s serial port, or through the

backplane when using the management software.

Please refer to the MultiModemManager software manual for instructions on how to update a modem’s

firmware using the management software.

Using FlashPro to Upgrade Firmware

1. Download FLASHPRO.ZIP and a new .HEX file from the Multi-Tech BBS.

2. Unzip the FLASHPRO.ZIP file. Place this unzipped file and the .HEX file in the same directory.

3. Run FlashPro by typing flashpro and pressing ENTER at the DOS prompt.

4. Highlight the Configure option in the Main Menu, and press ENTER. Highlight Active Port and

select the COM port to which the MT3334HD8 is attached. Highlight Baud Rate and select the rate

you want to program at. Press ESC when finished.

5. Highlight the Select File to Program option in the Main Menu. Highlight the .HEX file. Hit ESC

when finished.

6. Highlight the Program Firmware option in the Main Menu. You are prompted to confirm the file

to program.

7. Return to step 3, if you have not successfully programmed FlashPro, or call Multi-Tech's Technical

Support or BBS.

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Appendixes

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Appendix A ASCII Conversion Chart

CTRL CODE HEX DEC CODE HEX DEC CODE HEX DEC CODE HEX DEC

NUL

SOH

STX

ETX

EOT

ENQ

ACK

BEL

64 100

65 101

66 102

67 103

68 104

69 105

6A 106

6B 107

6C 108

6D 109

6E 110

6F 111

70 112

71 113

72 114

73 115

74 116

75 117

76 118

77 119

78 120

79 121

7A 122

7B 123

7C 124

7D 125

7E 126

7F 127

(

)

[

DLE

DC1

DC2

DC3

DC4

NAK

SYN

ETB

CAN

{

SUB

ESC

;

]

}

DEL

NUL

Null, or all zeros

Vertical Tab

SYN

Sync.

SOH Start of Header

Form Feed

ETB

CAN

End Transmission Block

Cancel

STX

ETX

EOT

Start of Text

Carriage Return

Shift Out

End of Text

End of Medium

Substitute

End of Transmission

Shift In

SUB

ESC

ENQ Enquiry

DLE

DC1

DC2

DC3

DC4

NAK

Data Link Escape

Device Control 1

Device Control 2

Device Control 3

Device Control 4

Escape

ACK

BEL

Acknowledge

File Separator

Group Separator

Record Separator

Unit Separator

Delete

Bell or Alarm

Backspace

Horizontal Tab

Line Feed

Negative Acknowledge

DEL

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Dial Pulses and Tones

Appendix B Dial Pulses and Tones

Dial Pulses

When you pulse dial, as when you make a call with a rotary dial telephone, your telephone or modem

generates codes in the form of pulses that simulate the opening and closing of old-fashioned electric

relays, or switches. The number of pulses in a code are the same as the digit they encode; thus, the digit 1 is

represented by one pulse, the digit 2 by two pulses, etc. In Figure B-1, the digit 2 is pulse dialed, followed

by the digit 1. Each pulse consists of an A ms open (break) and a B ms closed (make), where A is either 60

or 67 ms, and B is either 40 or 33 ms, for a total of 100 ms per cycle, or a rate of 10 pulses per second. The

interdigital pause time is 800 ms. The pulse ratios are controlled by the &P command.

Closed

Open

Digit 2

Digit 1

Figure B-1. Dial pulses

Tone Dial Frequencies

The tone dialing method combines two frequencies for each of the twelve digits found on a touch-tone dial

pad. This method is referred to as dual-tone multi-frequency (DTMF) dialing.

The four horizontal rows on a touch-tone keypad use four low-frequency tones (697, 770, 852, 941 Hz),

while the three vertical columns use three high-frequency tones (1209, 1336, 1477 Hz). The tone frequency

tolerance is 0.02%.

For example, the digit 4 is dialed by combining two tone frequencies: 770 Hz from the second row, and

1209 Hz from the first column. In another example, the digit 9 is dialed with tone frequencies 852 Hz and

1477 Hz.

697

770

852

941

Digits

1209

1336

1477

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Figure B-2. Standard DTMF frequencies

The extended DTMF characters (A, B, C, D) are the high-end frequencies (1633 Hz) defined on some

telephone sets with a fourth vertical column of buttons. This fourth column provides for extended PBX

control functions. The actual functions that are provided depend on the PBX manufacturer’s

implementation and feature set.

697

770

852

941

Digits

1209

1336

1477

1633

Figure B-3. Extended DTMF frequencies

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Result Code Summary

Appendix C Result Code Summary

Multi-Tech Result Codes (&Q0)

Terse Verbose

Definition

Command was executed without error; ready for next

command.

CONNECT

Modem has detected carrier and gone online.

RING

Modem has detected ring caused by incoming call.

No carrier signal has been detected within the allowed time.

Error in command line (too many, or invalid characters).

Modem has detected carrier at 1200 bps and gone online.

No dial tone has been detected.

NO CARRIER

ERROR

CONNECT 1200

NO DIALTONE

BUSY

A busy signal has been detected.

NO ANSWER

CONNECT 2400

The remote system did not answer.

Modem has detected carrier at 2400 bps and gone online.

Not used.

CONNECT 4800

CONNECT 9600

CONNECT 14400

CONNECT 19200

CONNECT 21600

CONNECT 1275

CONNECT 24000

CONNECT 26400

CONNECT 28800

CONNECT 31200

CONNECT 33600

Modem has detected carrier at 4800 bps and gone online.

Modem has detected carrier at 9600 bps and gone online.

Modem has detected carrier at 14400 bps and gone online.

Modem has detected carrier at 19200 bps and gone online.

Modem has detected carrier at 21600 bps and gone online.

Modem is connected in V.23 mode.

Modem has detected carrier at 24000 bps and gone online.

Modem has detected carrier at 26400 bps and gone online.

Modem has detected carrier at 28800 bps and gone online.

Modem has detected carrier at 31200 bps and gone online.

Modem has detected carrier at 33600 bps and gone online.

MNP Reliable Mode. If the modem connects using MNP error correction, the word RELIABLE or the

letter R is added to the CONNECT responses as follows:

CONNECT RELIABLE

CONNECT 1200 RELIABLE

CONNECT 2400 RELIABLE

CONNECT 4800 RELIABLE

CONNECT 9600 RELIABLE

CONNECT 14400 RELIABLE

CONNECT 19200 RELIABLE

CONNECT 21600 RELIABLE

CONNECT 24000 RELIABLE

CONNECT 26400 RELIABLE

CONNECT 28800 RELIABLE

CONNECT 31200 RELIABLE

CONNECT 33600 RELIABLE

11R

12R

13R

19R

21R

24R

26R

28R

31R

33R

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LAP-M Reliable Mode. If the modem connects using LAP-M error correction, the word LAPM or letter L

is added to the CONNECT responses as follows:

Connect LAPM

Connect 1200 LAPM

Connect 2400 LAPM

Connect 4800 LAPM

Connect 9600 LAPM

Connect 14400 LAPM

CONNECT 19200 LAPM

CONNECT 21600 LAPM

CONNECT 24000 LAPM

CONNECT 26400 LAPM

CONNECT 28800 LAPM

CONNECT 31200 LAPM

CONNECT 33600 LAPM

10L

12L

13L

19L

21L

24L

26L

28L

31L

33L

Data Compression. If the modem connects using data compression, the word COMPRESSED or the

letter C is added to the CONNECT responses.

Standard AT Result Codes (&Q1)

If standard AT command set responses are selected by the &Q command, the following result codes

change:

Not used.

CONNECT 2400

Modem has detected carrier at 2400 bps and

gone online.

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S-Register Summary

Appendix D S-Register Summary

Range

Default

Description

1 ring

0, 1–255

Sets the number of rings until the modem

answers. ATS0=0 disables auto answer

completely.

1 ring

decimal

1 sec

0–255

0–127

Counts the rings that have occurred.

43 (+)

13 (^M)

10 (^J)

8 (^H)

Sets ASCII code for the escape code character.

Sets ASCII code for the RETURN character.

Sets ASCII code for the LINE FEED character.

Sets ASCII code for the BACKSPACE character.

2–255

4–255†

4–7‡

4†

4‡

Sets the time the modem will wait for a dial tone

before aborting a call.

1 sec

1–255

1–45*

1–55‡

45*

55‡

Sets the time the modem will wait for a carrier

signal before aborting a call.

0–255

4–255†

4–7‡

4†

4‡

Sets the length of the pause caused by a comma

character in a dialing command.

100 ms

1 ms

1–255

Sets delay between when the modem detects a

valid carrier signal and when it turns on its CD

circuit.

S10

S11

1–254,

255

Sets how long a carrier signal must be lost before

the modem disconnects. S10=255 causes the

modem to not disconnect with loss of carrier.

1–255

80–255*

80*

Sets spacing and duration of dialing tones. 50

ms is the recommended minimum..

80–255‡ 80‡

S13

S17

decimal

10 ms

0, 1–127 37 (%)

Sets ASCII code for remote configuration escape

character. S13=0 disables remote configuration.

1–255

Sets the length of the break time (space) sent to

the local PC when the modem receives a remote

break.

S24

S25

S30

50 ms

100 ms

1 min.

0–255

Sets the time the DSR, CTS, and CD signals

drop before going high again. Used for some

PBX and CBX phone systems.

0, 1–255

Sets the time the DTR signal must be dropped

before the modem disconnects. The 0 default

equals 50 ms.

Sets how long the modem waits after the last

character is received or transmitted before it

disconnects. The 0 default disables the timer.

S32

S34

S36

S37

100 ms

0–255

0–60

Sets the time the modem will wait for a RETURN

to be entered during escape sequence execution.

1 char-

acter

Sets the number of command characters allowed

after +++AT.

1 sec

0, 1-255

0-255

Sets the time between DTR inactive and modem

off-hook. S36=0 disables DTR busy-out.

1 sec

Sets the time between DTR active and modem

on-hook.

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Range

Default

Description

S43

decimal

1 sec

33, 31,

28, 26,

24, 21,

19, 16,

14, 12,

96, or 48

Sets fixed V.34 connect speed. 28 = 28800 bps;

26 = 26400 bps;. . . 48 = 4800 bps. 0 default

disables this feature.

S48

S94

33, 31,

28, 26,

24, 21,

19, 16,

14, 12,

96, or 48

Sets maximum V.34 connect speed. 33 = 33600 bps;

31 = 31200 bps;. . . 48 = 4800 bps. 0 default

disables feature (same as S48=33).

0–254,

255

Sets the maximum time the modem remains out

of service when *H1 is active. S94=255 causes

the modem to remain out of service indefinitely,

until it receives an enable from the management

software.

* Values for International and Canadian modems only.

† Values for International modems only.

‡ Values for UK modems only.

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AT Command Summary

Appendix E AT Command Summary

Command

Values

Description

n/a

Attention Code

The attention code precedes all command lines

except A/, A: and escape codes.

RETURN

n/a

RETURN Key

Press the RETURN (ENTER) key to execute most

commands.

n/a

Force Answer Mode

Answer call immediately without waiting for ring.

Repeat Last Command

Do not precede this command with AT. Do not press

RETURN to execute.

n/a

Continuous Redial

Continuous redial of last number until answered. (10

redials in North American models. Not used on

International or U.K. models.)

&An

n = 0 or 1

Answerback

*** &A0 Answerback off.

&A1 Answerback on.

$An

Auto-Reliable Buffering

*** $A0 Discard data received during establishment of

reliable connection

$A1 Buffer data received during establishment of

reliable connection

#An

n = 0–3

Auto Speed Detection in Answer Mode

*** #A0 Start at maximum speed and fall back to 14400

to 12000 to 9600 to 4800 to 2400 to 1200 to 300

bps.

#A1 Maximum speed only.

#A2 Start at maximum speed and fall back

incrementally to 4800 bps only.

#A3 Start at 2400 bps and fall back to 1200 to 300

bps only.

n = 0 or 1

Answer Tone (International models only)

*** B0 Select ITU-T V.21 answer tone.

B1 Select Bell 103 answer tone.

&BSn

n = 0 or 1

Maximum Reliable Block Size

&BS0 Maximum transmit block size of 64 characters.

*** &BS1 Maximum transmit block size of 256 characters.

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Command

Values

Description

Baud Adjust

$BAn

n = 0 or 1

*** $BA0 Set baud adjust off, speed conversion on. (Serial

port speed is independent of modem data rate.)

$BA1 Set baud adjust on, speed conversion off.

(Serial port speed is same as modem data rate.)

&Cn

n = 0, 1, 2,

Carrier Detect Control

or 4

&C0 Force Carrier Detect on.

*** &C1 Let Carrier Detect follow carrier signal.

&C2 Let Carrier Detect drop for time set by S24 on

disconnect, then go high again.

&C4 Reset modem when Carrier Detect drops.

&CDn

n = 0 or 1

Cleardown at Disconnect

*** &CD0 Enable cleardown.

&CD1 Disable cleardown.

s = phone #

Dial

Dial telephone number s, where s may include up to

60 digits and the T, P, R, comma, colon, and semicolon

characters.

DsNd

s = phone #

Store Phone Number

d = 0 or 1

To store, enter D followed by telephone number s,

then N followed by directory number d.

&Dn

n = 0, 1, 2,

Data Terminal Ready Control

or 3

&D0 Modem ignores DTR signal.

&D1 When DTR drops, the modem hangs up. While

DTR is low, the modem accepts commands but

will not dial or auto-answer until DTR goes high

again.

*** &D2 Same as &D1.

&D3 When DTR drops, the modem hangs up and

resets as if an ATZ or an AT&F command was

issued.

%DCn

%DFn

%DPn

n = 0 or 1

Command Mode Control

*** %DC0 Enable command mode.

%DC1 Disable command mode.

Line Probe Data Format

*** %DF0 V.34 line probe data displayed in graph format.

%DF1 V.34 line probe data displayed in table format.

Line Probe Data Read

*** %DP0 Disable reading of line probe data during the

V.34 handshake.

%DP1 Enable reading of line probe data during the

V.34 handshake.

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AT Command Summary

Command

Values

Description

>DTn

n = 0 or 1

DTMF Detection

*** >DT0 Disable DTMF detection.

>DT1 Enable DTMF detection when off-hook.

n = 0 or 1

Echo Command Mode Characters

Do not echo command mode characters.

Do echo command mode characters.

*** E1

&En

n = 0–15

V.42 Error Correction Modes

&E0 Non-error correction mode (V.42 disabled).

*** &E1 Auto-reliable mode.

&E2 Reliable mode (V.42 enabled).

Modem-Initiated Flow Control

&E3 Flow control disabled.

*** &E4 Hardware flow control.

&E5 XON/XOFF flow control.

XON/XOFF Pass-Through (&E5 selected)

*** &E6 XON/XOFF not passed through.

&E7 XON/XOFF passed through.

Hewlett-Packard ENQ/ACK Pacing

*** &E8 ENQ/ACK pacing off.

&E9 ENQ/ACK pacing on.

Non-Error Correction Mode Flow Control

*** &E10 Non-error correction mode flow control off.

&E11 Non-error correction mode flow control on.

Pacing (Computer-Initiated Flow Control)

&E12 Pacing off.

*** &E13 Pacing on.

Data Compression

&E14 Data compression disabled.

*** &E15 Data compression enabled.

$En

n = 0 or 1

V.42 Error Correction at 300 bps

*** $E0 V.42 error correction at 300 bps disabled.

$E1 V.42 error correction at 300 bps enabled.

$EBn

n = 0 or 1

Asynchronous Word Length

*** $EB0 10-bit mode enabled.

$EB1 11-bit mode enabled.

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Command

Values

Description

%En

n = 0–5

Escape Sequence Options

%E0 Modem won’t escape.

*** %E1 +++ method

%E2 Break method.

%E3 Either +++ or break methods.

*** %E4 No OK response to +++.

%E5 OK response to +++.

&Fn

n = 0, 8, or 9

Load Default Configuration

&F0 Load factory default values from ROM.

*** &F8 Read factory default values and DIP switch

settings when &F is issued.

&F9 Read parameters stored in nonvolatile memory

when &F is issued.

$Fn

%Fn

#Fn

n = 0 or 1

Auto-Reliable Fallback Character Enable

*** $F0 Do not fall back to non-error correction mode

connect if CR received.

$F1 Fall back to non-error correction mode connect

if CR received.

n = 0 or 1

Echo Canceler Offset Frequency Compensation

*** %F0 Disable echo canceler offset frequency

compensation.

%F1 Enable echo canceler offset frequency

compensation.

n = 0, 1, or 2

Fallback Modes When Online

#F0 No fallback when online.

#F1 Fall back incrementally from maximum speed to

4800 bps.

*** #F2 Fall back incrementally to 4800 bps, fall forward

when line improves.

&Gn

n = 0, 1, or 2

Guard Tones (International model only)

*** &G0 Turn off ITU-T guard tones.

&G1 Turn on ITU-T 550 Hz guard tone.

&G2 Turn on ITU-T 1800 Hz guard tone.

Note: The U.K. model is locked to &G2, which turns

on the ITU-T 1800 Hz guard tone.

n = 0 or 1

On-Hook/Off-Hook

Go on-hook (hang up).

Go off-hook.

*Hn

n = 0 or 1

Busy-Out After Disconnect

*** *H0 Disable busy-out after disconnect.

*H1 Enable busy-out after disconnect.

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AT Command Summary

Command

Values

n = 0, 1, 2,

or 5

Description

Inquire Product Codes

Request modem ID #.

Request firmware revision #.

Request modem description.

Request DSP version.

#Ix

x = password

Enter Login Password

Password is case sensitive.

#I=x

x = password

Store Login Password

Password must be 6–10 characters long, and may

consist of any keyboard characters.

n = 0, 5–11

List Commands

List stored telephone numbers.

List current operating parameters.

List current S-register values.

List additional parameters.

List online diagnostic parameters.

List line probe signal strength data.

L10 List line probe signal to noise ratio.

L11 List line probe noise data.

Note: To use L9, L10, or L11 when online, you must

first escape to command mode by typing

+++ATLn<CR> (for n type 9, 10, or 11). Type ATO to

return on line.

#Ln

n = 0, 1, 2, 3,

V.42 Error Correction Mode

or 8

*** #L0 Modems negotiate V.42 mode.

#L1 MNP on and LAP-M off (originate mode only).

#L2 LAP-M on and MNP off (originate mode only).

#L3 Disable detection phase and go directly to LAP-M.

n = 0, 1, 2,

Modem Speaker Control

or 3

M0 Modem speaker always off.

*** M1 Modem speaker on until carrier signal detected.

M2 Modem speaker always on.

M3 Monitor speaker on during dialing, off during

handshaking.

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Command

Values

Description

$MBn

n = speed

Modem Baud Rate

$MB75

Select ITU-T V.23 mode.

Select 300 bps on line.

$MB300

$MB1200 Select 1200 bps on line.

$MB2400 Select 2400 bps on line.

$MB4800 Select 4800 bps on line.

$MB7200 Select 7200 bps on line.

$MB9600 Select 9600 bps on line.

$MB12000 Select 12,000 bps on line.

$MB14400 Select 14,400 bps on line.

$MB16800 Select 16,800 bps on line.

$MB19200 Select 19,200 bps on line.

$MB28800 Select 28,800 bps on line.

*** $MB33600 Select 33,600 bps on line.

d = 0 or 1

Dial a Stored Number

Dial stored telephone number d.

NdNe...

d = 0 or 1

Number Linking

e = 1 or 0

Dial stored number d; if that is busy, dial stored

number e. The command may be extended

NdNeNdNe... to cycle between the two numbers.

n/a

Go Back On Line

Exit command mode and go into online mode after

using the escape code to do the reverse.

In dialing

command

*** Pulse-Dial

Modem pulse-dials numbers that follow P.

&Pn

n = 0 or 1

Set Pulse Dial Ratios

*** &P0 60:40 pulse ratio.

&P1 67:33 pulse ratio.

Note: The ZDXK is locked to &P1, a 67:33 ratio.

n = 0–2

Result Codes Enable/Disable

*** Q0

Result codes sent.

Result codes suppressed (quiet).

No Response answer mode.

&Qn

n = 0 or 1

Result Codes (Multi-Tech or Standard AT)

*** &Q0 Multi-Tech responses with modifiers.

&Q1 Standard AT responses with no modifiers.

n = 0 or 1

Reverse Originate/Answer Mode

*** R0

Modem will not reverse modes.

Modem will reverse modes when R is added to

dial string.

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AT Command Summary

Command

Values

Description

Clear to Send Control

&Rn

n = 0, 1, or 2

&R0 Let CTS state follow RTS state when online.

*** &R1 Force CTS high (on).

&R2 Let CTS drop on disconnect for time set by S24,

then go high again.

&RAn

&RDn

&RFn

n = 0 or 1

Asymmetric Bit Rate

*** &RA0 Enable asymmetric bit rate operation.

&RA1 Disable asymmetric bit rate operation.

Square Wave Ring Detect

&RD0 Full wave ring detect only.

*** &RD1 Full wave and square wave ring detect.

CTS/RTS Interaction Control

&RF0 Let CTS follow RTS.

*** &RF1 Let CTS act independently.

&RN

&RP

n/a

Rate Renegotiation

Forces the modem to renegotiate the data rate.

Immediate Line Probe

Initiates a retrain that makes the modem read line

probe information if %DP1 is selected. Valid only

when online in V.34 mode.

&RR

n/a

Retrain

Initiates an immediate retrain without a line probe

reading.

$Rn

n = 0 or 1

Retransmit Count

*** $R0 Disconnect after 12 retransmits.

$R1 Do not disconnect after 12 retransmits.

Sr=n

Sr?

r = 0–11, 13,

24, 25, 30,

32, 34, 36,

37, 43, 48, or

94; n varies

Set Register Value

Set value of S-register r to value of n, where n is

entered in decimal format.

r = 0–11, 13,

24, 25, 30,

32, 34, 36,

37, 43, 48, or

Read Register Value

Read value of S-register r and display value in 3-digit

decimal form.

&Sn

n = 0, 1, or 2

Data Set Ready Control

&S0 Force DSR high (on).

*** &S1 Let DSR follow CD.

&S2 DSR drops on disconnect for time set by S24,

then goes high again.

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Command

Values

Description

&SFn

n = 0 or 1

DSR/CD Interaction Control

*** &SF0 Select DSR to follow CD.

&SF1 Select DSR to be independent.

$SBn

n = speed

Baud Adjust

($BA) must

be off.

Serial Port Baud Rate

$SB300

Select 300 bps at serial port.

Select 1200 bps at serial port.

Select 2400 bps at serial port.

Select 4800 bps at serial port.

Select 9600 bps at serial port.

$SB1200

$SB2400

$SB4800

$SB9600

$SB12000 Select 12,000 bps at serial port.

$SB19200 Select 19,200 bps at serial port.

$SB38400 Select 38,400 bps at serial port.

$SB57600 Select 57,600 bps at serial port.

*** $SB115200 Select 115,200 bps at serial port.

#Sy

y = password

Enter Setup Password

Password is case sensitive.

#S=y

y = password

Store Setup Password

Password must be 6–10 characters long, and may

consist of any keyboard characters.

In dialing

command

Tone-Dial

Modem tone-dials numbers following the T.

&Tn

n = 4 or 5

Respond to Remote Digital Loopback Signal

&T4 Enable response to remote digital loopback

signal.

*** &T5 Disable response to remote digital loopback

signal.

$Tn

#Tn

n = 0 or 1

n = 0–3

Calling Tone

$T0 Enable calling tone.

*** $T1 Disable calling tone.

Trellis-Coded Modulation

#T0 Disable trellis-coded modulation.

*** #T1 Enable trellis-coded modulation.

Loopback Test Modes

Enable analog loop originate mode.

Enable analog loop answer mode.

Enable remote digital loopback mode.

Enable local digital loopback mode.

n = 0 or 1

Result Codes (Verbose/Terse)

Result codes sent as digits (terse response).

*** V1

Result codes sent as words (verbose

response).

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AT Command Summary

Command

Values

Description

V.32terbo Handshake

#Vn

n = 0 or 1

*** #V0 Enable V.32terbo tones in answer mode.

#V1 Disable V.32terbo tones in answer mode.

In dialing

command

Wait for New Dial Tone

Causes modem to wait for new dial tone. (X2 or X4

must be selected.)

&Wn

n = 0 or 1

Store Configuration

&W0 Store current settings in NVRAM; modem will

load these at power-on or with the ATZ

command instead of reading factory ROM

defaults.

*** &W1 Do not store settings.

n = 0–4

Result Codes and Call Progress Selection

*** X0

Basic result codes (CONNECT only); does not

look for dial tone or busy.

Extended result codes (w/ CONNECT 1200,

CONNECT 2400, etc.); does not look for dial

tone or busy signal.

Extended result codes with NO DIAL TONE;

does not look for busy signal.

Extended result codes with BUSY; does not look

for dial tone.

Extended result codes with NO DIAL TONE

and BUSY.

#Xn

n = 0 or 1

Number of XOFF Characters Sent

*** #X0 Single XOFF character sent after buffer is full.

#X1 Multiple XOFF characters sent (one for every

character received after buffer is full).

n = 0 or 1

Long Space Disconnect

*** Y0

Disable sending or responding to long space

break signal on disconnect.

Enable sending or responding to long space

break signal on disconnect. (Both modems

must have Y1 set.)

n/a

Modem Reset

Reset modem to default values. Defaults come from

NVRAM if &W0 is set, from ROM if &W1 is set.

In dial

Dialing Pause

command

Comma; causes dialing pause for time set by S8.

At end of dial

command

Continuous Redial

Colon; causes continuous redial of number until

answered (10 in North American models). Not used in

U.K. or International models.

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Command

Values

Description

;

At end of dial

command

Return to Command Mode After Dialing

Semi-colon; causes immediate return to command

mode after dialing.

In dial

Flash On-Hook

command

Exclamation; causes modem to flash on-hook.

In dial

Quiet Answer

command

Causes modem to wait for a ringback, then 5 seconds

of silence before processing next part of command.

In dial

Call Card Tone Detect

command

Causes modem to wait for a call card tone before

processing next part of command.

+++AT<CR>

Escape Sequence

Puts modem in command mode while still remaining

on line. Type +++ followed by the letters A and T, up

to ten command characters (or as defined by S34),

and a RETURN.

%%%AT<CR>

Break Escape Sequence

Alternate escape method. Puts modem in command

mode while still remaining on line. Enter break signal

followed by the letters A and T, up to sixty command

characters, and a RETURN.

Remote Configuration Escape Sequence

Cause remote modem to display remote configuration

menu. Type %%% (or as defined in register S13)

followed by the letters A and T, and a RETURN.

* Factory default on International model

** Not available on U.K. model

*** Factory default on North American model

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Remote Configuration

Appendix F Remote Configuration

Introduction

Remote configuration, a feature of Multi-Tech’s MT3334HD8 modems, is a network management tool that

allows you to configure modems anywhere in your network from one location. With password-protected

remote configuration, you can issue AT commands to a remote Multi-Tech modem for maintenance or

troubleshooting as if you were on site.

Basic Procedure

The following steps are valid regardless of whether the connection is established by the local or the remote

Multi-Tech modem.

1. Establish a data connection with a remote modem that has the remote configuration feature.

2. Send three remote configuration escape characters followed by AT and an ENTER. Example:

%%%AT<CR>. The remote modem responds with the following menu:

1. DATA Mode

2. COMMAND Mode

3. Enter the number 2. The remote modem responds with a request for the setup password:

Password>

4. Enter your setup password. If the password is correct, the remote modem responds with:

5. You can now send AT commands to the remote modem.

6. When you have finished configuring the remote modem, save the new configuration by typing

AT&W0<CR>, then type ATO<CR> to exit remote configuration. The modem responds with the

following menu:

1. DATA Mode

2. COMMAND Mode

7. Type the number 1 to return to data mode. You can then break the connection in the normal way.

CAUTION: If you hang up while you are in remote configuration mode, it may lock up the remote modem.

Setup

The first time you configure a modem remotely, you should set its passwords and possibly its remote

configuration escape character. Multi-Tech modems are shipped with a default login password (MULTI-

TECH) and setup password (MODEMSETUP). Because anyone who has an owner’s manual knows the

default passwords, for security you should change them—but don’t forget them!

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Changing the Passwords

1. Establish a remote configuration link with the remote modem as described above.

2. Type AT#IMULTI-TECH (or AT#Ixxxxxx if you have replaced the MULTI-TECH password with

xxxxxx) and press ENTER. The modem responds with OK if the login password is correct, and

ERROR if it is wrong.

3. Type AT#SMODEMSETUP (or AT#Syyyyyy if you have replaced the MODEMSETUP password

with yyyyyy) and press ENTER. The modem responds with OK if the setup password is correct, and

ERROR if it is wrong.

4. To change the login password, type AT#I=xxxxxx, where xxxxxx stands for the password, and

press ENTER. The password may include any keyboard characters, but must besixtotencharacterslong.

ThemodemrespondswithOK.

5. To change the setup password, type AT#S=yyyyyy, where yyyyyy stands for the password, and

press ENTER. The password may include any keyboard characters, but must be six to ten characters

long. The modem responds with OK.

6. The new passwords are saved automatically. You may now either enter more AT commands or exit

remote configuration with ATO<CR>. The next time you remotely configure the modem you must

use the new setup password.

Note: Passwords are case sensitive. The next time you enter the password, it must be in the same case as

you set it up.

Changing the Remote Escape Character

To increase security, you may wish to change the remote modem’s remote configuration escape character.

The remote configuration escape character is stored in register S13. The factory default is 37, which is the

ASCII code for the percent character (%). Setting S13 to 0 (zero) will disable remote configuration

entirely—but if you do this remotely, you won’t be able to change it back remotely!

1. Establish a remote configuration link with the remote modem as described above.

2. Type ATS13=n, where n is the ASCII code for the new remote configuration escape character, then

press ENTER.

3. Save the new value by typing AT&W and pressing ENTER.

4. Type ATO<CR>, then 1, to exit remote configuration.

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Index

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MT3334HD8 User Guide

&CD, 25

&D, 29

&E0, 31

abort timer, 12, 19, 47, 51

Answer command, 12, 40

&E1, 31

answer mode, 18, 34, 40

&E2, 31

Answer Tone command, 24

&E3, 37

Answerback command, 24

&E4, 37

answering a call, 40, 51

&E5, 37

ASCII code, 68

&E6, 37

Asymmetric Bit Rate command, 28

&E7, 37

Asynchronous Word Length command, 37

&E8, 38

AT Command Control command, 12, 25

&E9, 38

AT commands

attention code, 12, 13

command string limit, 13

disabling command mode, 12, 25

parameters, 13

summary, 75

A, 12, 40

A/, 35

&E10, 38

&E11, 38

&E12, 38

&E13, 38

&E14, 31

&E15, 31

&F, 21, 52

&G, 26

A:, 16

AT, 12, 13

B, 24

D, 12, 16

D...N..., 19, 20

E, 22

H, 16

I, 35, 61

L, 20

L5, 35, 52

L6, 36, 52

L7, 35, 52

L8, 36, 42

L9, 42

&P, 27, 69

&Q, 23, 71, 72

&R, 30, 49

&RA, 28

&RD, 27

&RF, 30

&RN, 36

&RP, 42

&RR, 36

&S, 30, 49

&SF, 30

&T, 42, 55

&W, 20, 21, 22, 51, 52

$, 19

L10, 42

$A, 32

L11, 42

N, 20

$BA, 33, 34

$E, 32

N...N..., 20

O, 40

$EB, 37

$F, 32

P, 17

Q, 22

$MB, 24, 34

$R, 33

R, 18

$SB, 34

S ?, 51

$T, 27

S =, 51

#A, 24

T, 17

#F, 26

U, 43

#I, 40

V, 23

#L, 31

W, 17

#S, 41

X, 17, 18, 23

Y, 28

#T, 27

#X, 38

Z, 22

&A, 24

&BS, 36

&C, 29, 49

%%%AT<CR>, 40

%DC, 12, 25

%DF, 41, 42

%DP, 41

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Index

%E, 39

%F, 28

command buffer, 13, 50

command mode, 12

>DT, 25

disabling, 12, 25

*H, 26, 51

! (exclamation mark), 18

, (comma), 18, 48

command mode control, 25

command string, 12, 19

CompuServe, 63

: (colon), 16, 18

; (semicolon), 18

@, 19

configuration, remote, 85

Continuous Redial command, 16, 18

CTS signal

+++AT<CR>, 39

control of, 30

<BREAK>AT<CR>, 39

auto answer, 12, 33, 46, 51

disabling, 46

Auto Speed Detection command, 24

Auto-Reliable Buffering command, 32

Auto-Reliable Fallback Character command, 32

auto-reliable mode, 31, 32

Auto-Reliable Mode command, 31

disconnect drop time, 49

flow control, 37

interaction with RTS signal, 30

CTS/RTS interaction control, 30

DAA, 2

data bit, 37

data compression and speed conversion, 33

Data Compression command, 31

Data Set Ready Control command, 30

Data Terminal Ready Control command, 29

diagnostic commands, 42

Dial a Stored Number command, 20

Dial command, 12, 16

dial tone, 16

backspace character, 13, 47

Baud Adjust command, 33

baud rate

modem, 34

serial port, 33, 34

BBS, Multi-Tech, 62

Bell standards, 24

wait time, 23, 47

blind dialing, 16, 20, 23

break signal, 28, 49

dialing

a phone number, 16

escape sequence, 39

a stored number, 20

busy signal, 16, 18, 19, 20, 23, 26, 48

Busy-Out After Disconnect command, 26, 51

busy-out state, 2

blind dialing, 16, 20, 23

continuous redialing, 16

modifiers, 17

pause time, 18, 48, 51

smart dialing, 16, 23

Dialing Pause command, 18

dimensions of MT3334HD8, 6

disconnecting, 33

after DTR drop, 49

drop time, 29, 30, 49

inactivity timer, 49

Display Line Probe Data command, 42

DSR signal

Call Card Tone Detect command, 19

Calling Tone command, 27

Canadian Limitations Notice, iv

carriage return character, 47

Carrier Detect Control command, 29

carrier, loss of, 48

CBX phone systems, 29, 30, 49

CC9600 chassis, 8, 9

control of, 30

CD signal, 2

control of, 29

disconnect drop time, 49

interaction with DSR signal, 30

LED indicator, 55

disconnect drop time, 49

interaction with CD signal, 30

DTE (data terminal equipment), 38

DTMF (dual tone multifrequency)

detection, 25

response time, 48

dialing, 17

Clear to Send Control command, 30

Cleardown at Disconnect command, 25

comma, 48

frequencies, 69

DTMF Detection command, 25

DTR signal

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busy-in time, 50

busy-out time, 50

control of, 29

handshake, 24

hanging up, 16, 39

disconnect drop time, 49

Hardware Flow Control command, 37

Echo Canceler Frequency Offset Compensation command,

Immediate Line Probe command, 42

inactivity timer, 49

in-band escape sequence, 39

indicators, 2

Echo Command Mode Characters command, 22

ENQ/ACK Pacing command, 38

error correction

Inquire Product Code command, 35

installation, 8, 9

at 300 bps, 32

automatic, 31

Internet, 2

disabling, 31

selecting, 31, 32

Error Correction Modes command, 31

escape code character, 46

Escape Sequence Options command, 39

escape sequences

+++AT<CR>, 39

<BREAK>AT<CR>, 39

options, 39

remote configuration, 40

timeout, 49

Extended codes, 23

LED indicators, 2

line feed character, 47

List Current Operating Parameters command, 35

List Current S-Register Values command, 36

List Online Diagnostics command, 36

List Stored Telephone Numbers command, 20

listing stored values, 20, 35, 36

Load Default Configuration command, 21

long space break, 28

Long Space Disconnect command, 28

Loopback Test Modes command, 43

loopback testing, 54

fallback, 24, 26

Fallback Modes command, 26

fax warning, iv

fax-back service, 64

FCC regulations, iii, 2

Flash On-Hook command, 18

FlashPro, 64

flow control, 30, 36, 37, 38

commands, 36

manual organization, 3

Maximum Reliable Block Size command, 36

memory

nonvolatile (NVRAM), 13, 19, 20, 21, 22, 52

read-only (ROM), 13, 20, 21, 22, 52

MNP 3–5, 36

CTS/RTS enable, 37

disabling, 37

MNP error correction enable, 31

Modem Baud Rate command, 24, 34

MultiModemManager software, 10, 54

Multi-Tech BBS, 62

non-error correction mode, 38

XON/XOFF pass through, 37

Flow Control Disable command, 37

Format Line Probe Data command, 41, 42

front panel, 8

fuses, 6

noise, 27, 49

non-error correction mode, 32, 38, 49

Non-Error Correction Mode Flow Control command, 38

Number Linking command, 20

Go Back Online command, 40

Guard Tones command, 26

Number of XOFF Characters command, 38

NVRAM (nonvolatile random access memory), 13, 19, 20,

21, 22, 52

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Index

Result Codes Enable/Disable command, 22

Retrain command, 36

Retransmit Count command, 33

return character, 47

Return to Command Mode command, 18

Reverse Originate/Answer Mode command, 18

rings

On-Hook/Off-Hook command, 16

online connection commands, 24

online mode, 12, 40, 46, 54, 56

originate mode, 18, 34, 54

originating a call, 31, 34

out-of-band escape sequence, 39

out-of-service state (OOS), 2

out-of-service time, 26, 51

counting, 46

number till answer, 46, 51

square wave detection, 27

ROM (read-only memory), 13, 20, 21, 22, 52

RS-232C, 29, 30, 37

controls, 29, 30

RTS signal, 30

pacing, 36, 37, 38

enable/disable, 38

ENQ/ACK, 38

interaction with CTS signal, 30

Pacing command, 38

parameters, 13, 20, 35

default, 13, 29

safety, 8

parity, 37

self-test, 10

PBX phone systems, 17, 49

PBX/CBX disconnect drop time, 30, 49

power, 2, 6

serial port baud rate, 34

service, 60

Set Pulse Dial Ratios command, 69

PS9600 power supplies, 9

pulse ratios, setting, 69

Pulse-Dial command, 17

Pulse-Dial Ratios command, 27

Setup Password command, 41

smart dialing, 16, 18, 23

specifications, 4

speed conversion, 33, 34

Square Wave Ring Detect command, 27

S-registers, 36, 52

definition, 46

reading, 52

summary, 73

S0, 46, 51

S1, 46

S2, 46

S3, 47

S4, 47

Quiet Answer command, 19

Rate Renegotiation command, 36

Read Line Probe Data command, 41

reliable mode, 31, 36

Reliable Mode command, 31

remote configuration escape character, 48

Remote Digital Loopback command, 42

Repeat Last Command command, 35

Reset Modem command, 22

result codes, 13, 22, 23

call progress selection, 23

enable/disable, 22

extended codes, 23

Multi-Tech, 71

set selection, 23

standard, 72

summary, 71

verbose/terse selection, 23

Result Codes (Multi-Tech or Standard AT) command, 23

Result Codes (Verbose/Terse) command, 23

Result Codes and Call Progress Selection command, 17, 23

S5, 13, 47

S6, 16, 23, 47

S7, 12, 19, 47, 51

S8, 18, 48, 51

S9, 48

S10, 48

S11, 48

S13, 48

S17, 49

S24, 30, 49

S25, 49

S30, 49

S32, 49

S34, 50

S36, 50

S37, 50

S43, 50

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S48, 50

S94, 26, 51

V.21, 24

start bit, 37

V.22, 24

stop bit, 37

V.22bis, 24

V.32, 25, 26

V.32bis, 25, 26

Store Configuration command, 20, 21, 22, 52

Store Phone Number command, 19, 20

storing a configuration, 20, 51

V.34, 25, 26

asymmetric bit rate, 28

connect speed, 50

technical specifications, 4

technical support, 61, 63

terminal mode, 56

testing, 42, 55, 56, 57

commands, 42

echo canceler frequency offset compensation, 28

V.42, 31, 32

V.42 Error Correction at 300 bps command, 32

V.42 Error Correction Mode command, 31

loopback tests, 42, 43, 54, 56

tone detection, 25

tone dialing, 69

Tone-Dial command, 17

tone-dialing, 48

Wait for New Dial Tone command, 17

wait-for-carrier mode, 12

warranty, 60

World Wide Web, 64

transmission speed, 33, 34

Trellis-Coded Modulation command, 27

XON/XOFF, 37, 38

XON/XOFF Flow Control command, 37

XON/XOFF Pass-Through command, 37

upgrading the firmware, 64

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P/N 82063701

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