Important Information
Warranty
The NI 5911 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by
receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the
warranty period. This warranty includes parts and labor.
The media on which you receive National Instruments software are warranted not to fail to execute programming instructions, due to defects
in materials and workmanship, for a period of 90 days from date of shipment, as evidenced by receipts or other documentation. National
Instruments will, at its option, repair or replace software media that do not execute programming instructions if National Instruments receives
notice of such defects during the warranty period. National Instruments does not warrant that the operation of the software shall be
uninterrupted or error free.
A Return Material Authorization (RMA) number must be obtained from the factory and clearly marked on the outside of the package before
any equipment will be accepted for warranty work. National Instruments will pay the shipping costs of returning to the owner parts which are
covered by warranty.
National Instruments believes that the information in this document is accurate. The document has been carefully reviewed for technical
accuracy. In the event that technical or typographical errors exist, National Instruments reserves the right to make changes to subsequent
editions of this document without prior notice to holders of this edition. The reader should consult National Instruments if errors are suspected.
In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it.
EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF
NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER. NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR
DAMAGES RESULTING FROM LOSS OF DATA, PROFITS, USE OF PRODUCTS, OR INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY
THEREOF. This limitation of the liability of National Instruments will apply regardless of the form of action, whether in contract or tort, including
negligence. Any action against National Instruments must be brought within one year after the cause of action accrues. National Instruments
shall not be liable for any delay in performance due to causes beyond its reasonable control. The warranty provided herein does not cover
damages, defects, malfunctions, or service failures caused by owner’s failure to follow the National Instruments installation, operation, or
maintenance instructions; owner’s modification of the product; owner’s abuse, misuse, or negligent acts; and power failure or surges, fire,
flood, accident, actions of third parties, or other events outside reasonable control.
Copyright
Under the copyright laws, this publication may not be reproduced or transmitted in any form, electronic or mechanical, including photocopying,
recording, storing in an information retrieval system, or translating, in whole or in part, without the prior written consent of National
Instruments Corporation.
Trademarks
CVI™, DAQPad™, Flex ADC™, LabVIEW™, National Instruments™, NI™, ni.com™, NI-DAQ™, RTSI™, and SCXI™ are trademarks of
National Instruments Corporation.
Product and company names mentioned herein are trademarks or trade names of their respective companies.
Patents
For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txtfile
on your CD, or ni.com/patents.
WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS
(1) NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF
RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN
ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT
INJURY TO A HUMAN.
(2) IN ANY APPLICATION, INCLUDING THE ABOVE, RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE
IMPAIRED BY ADVERSE FACTORS, INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY,
COMPUTER HARDWARE MALFUNCTIONS, COMPUTER OPERATING SYSTEM SOFTWARE FITNESS, FITNESS OF COMPILERS
AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION, INSTALLATION ERRORS, SOFTWARE AND
HARDWARE COMPATIBILITY PROBLEMS, MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL
DEVICES, TRANSIENT FAILURES OF ELECTRONIC SYSTEMS (HARDWARE AND/OR SOFTWARE), UNANTICIPATED USES OR
MISUSES, OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER (ADVERSE FACTORS SUCH AS THESE ARE
HEREAFTER COLLECTIVELY TERMED “SYSTEM FAILURES”). ANY APPLICATION WHERE A SYSTEM FAILURE WOULD
CREATE A RISK OF HARM TO PROPERTY OR PERSONS (INCLUDING THE RISK OF BODILY INJURY AND DEATH) SHOULD
NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE. TO AVOID
DAMAGE, INJURY, OR DEATH, THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO
PROTECT AGAINST SYSTEM FAILURES, INCLUDING BUT NOT LIMITED TO BACK-UP OR SHUT DOWN MECHANISMS.
BECAUSE EACH END-USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS' TESTING
PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN
COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL
INSTRUMENTS, THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING
THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE
INCORPORATED IN A SYSTEM OR APPLICATION, INCLUDING, WITHOUT LIMITATION, THE APPROPRIATE DESIGN,
PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION.
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Compliance
FCC/Canada Radio Frequency Interference Compliance
Determining FCC Class
The Federal Communications Commission (FCC) has rules to protect wireless communications from interference. The FCC
places digital electronics into two classes. These classes are known as Class A (for use in industrial-commercial locations only)
or Class B (for use in residential or commercial locations). All National Instruments (NI) products are FCC Class A products.
Depending on where it is operated, this Class A product could be subject to restrictions in the FCC rules. (In Canada, the
Department of Communications (DOC), of Industry Canada, regulates wireless interference in much the same way.) Digital
electronics emit weak signals during normal operation that can affect radio, television, or other wireless products.
All Class A products display a simple warning statement of one paragraph in length regarding interference and undesired
operation. The FCC rules have restrictions regarding the locations where FCC Class A products can be operated.
FCC/DOC Warnings
This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance with the instructions
in this manual and the CE marking Declaration of Conformity*, may cause interference to radio and television reception.
Classification requirements are the same for the Federal Communications Commission (FCC) and the Canadian Department of
Communications (DOC).
Changes or modifications not expressly approved by NI could void the user’s authority to operate the equipment under the FCC
Rules.
Class A
Federal Communications Commission
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 is required to correct the interference
at their own expense.
Canadian Department of Communications
This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.
Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Compliance to EU Directives
Readers in the European Union (EU) must refer to the manufacturer’s Declaration of Conformity (DoC) for information*
pertaining to the CE marking compliance scheme. The manufacturer includes a DoC for most hardware products except for those
bought from OEMs. In addition, DoCs are usually not provided if compliance is not required, for example electrically benign
apparatus or cables.
To obtain the DoC for this product, click Declaration of Conformity at ni.com/hardref.nsf/. This Web site lists the DoCs
by product family. Select the appropriate product family, followed by your product, and a link to the DoC appears in Adobe
Acrobat format. Click the Acrobat icon to download or read the DoC.
*
The CE marking Declaration of Conformity contains important supplementary information and instructions for the user or
installer.
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About This Manual
Conventions ...................................................................................................................vii
Chapter 1
Installing the NI 5911 ....................................................................................................1-1
Acquiring Data with the NI 5911 ..................................................................................1-3
Chapter 2
Differential Input.............................................................................................2-1
Input Impedance..............................................................................................2-3
What Self-Calibration Does ............................................................................2-7
Why Warnings Occur During Acquisition........................................2-8
External Calibration.........................................................................................2-8
Triggering and Arming ..................................................................................................2-8
Analog Trigger Circuit ....................................................................................2-9
Trigger Holdoff ...............................................................................................2-10
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Contents
Triggering and Memory Usage....................................................................... 2-10
Multi-Record Acquisitions............................................................................................ 2-11
RTSI Bus and Clock PFI............................................................................................... 2-11
PFI Lines......................................................................................................... 2-11
PFI Lines as Inputs ........................................................................... 2-12
PFI Lines as Outputs......................................................................... 2-12
Synchronization .............................................................................................. 2-12
Appendix A
Technical Support and Professional Services
Glossary
Index
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About This Manual
The NI 5911 User Manual provides information on installing, connecting
signals to, and acquiring data from your NI 5911 high-speed digitizer. This
manual includes an overview of the NI 5911 and explains the operation of
each functional unit of the NI 5911.
Conventions
The following conventions appear in this manual:
<>
Angle brackets that contain numbers separated by an ellipsis represent a
range of values associated with a bit or signal name—for example,
DIO<3..0>.
»
The » symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.
This icon denotes a note, which alerts you to important information.
This icon denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash.
bold
Bold text denotes items that you must select or click in the software, such
as menu items and dialog box options. Bold text also denotes parameter
names.
italic
Italic text denotes variables, emphasis, a cross reference, or an introduction
to a key concept. This font also denotes text that is a placeholder for a word
or value that you must supply.
monospace
Text in this font denotes text or characters that you should enter from the
keyboard, sections of code, programming examples, and syntax examples.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames and extensions, and code excerpts.
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Related Documentation
The following documents contain information that you might find helpful
as you read this manual:
•
•
•
Where to Start with Your NI Digitizer
NI-SCOPE Software User Manual
NI-SCOPE Instrument Driver Quick Reference Guide
You can download these documents from ni.com/manuals.
Safety Information
This section contains important safety information that you must follow
when installing and using the device.
Do not operate the device in a manner not specified in this document.
Misuse of the device can result in a hazard. You can compromise the safety
protection built into the device if the device is damaged in any way. If the
device is damaged, return it to National Instruments (NI) for repair.
Do not substitute parts or modify the device except as described in this
document. Use the device only with the chassis, devices, accessories, and
cables specified in the installation instructions. You must have all covers
and filler panels installed during operation of the device.
Do not operate the device in an explosive atmosphere or where there may
be flammable gases or fumes. If you must operate the device in such an
environment, it must be in a suitably rated enclosure.
If you need to clean the device, use a soft, nonmetallic brush. Make sure
that the device is completely dry and free from contaminants before
returning it to service.
Operate the device only at or below Pollution Degree 2. Pollution is foreign
matter in a solid, liquid, or gaseous state that can reduce dielectric strength
or surface resistivity. The following is a description of pollution degrees:
•
Pollution Degree 1 means no pollution or only dry, nonconductive
pollution occurs. The pollution has no influence.
Pollution Degree 2 means that only nonconductive pollution occurs in
most cases. Occasionally, however, a temporary conductivity caused
by condensation must be expected.
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•
Pollution Degree 3 means that conductive pollution occurs, or dry,
nonconductive pollution occurs that becomes conductive due to
condensation.
You must insulate signal connections for the maximum voltage for which
the device is rated. Do not exceed the maximum ratings for the device. Do
not install wiring while the device is live with electrical signals. Do not
remove or add connector blocks when power is connected to the system.
Avoid contact between your body and the connector block signal when hot
swapping devices. Remove power from signal lines before connecting them
to or disconnecting them from the device.
Operate the device at or below the installation category1 marked on the
hardware label. Measurement circuits are subjected to working voltages2
and transient stresses (overvoltage) from the circuit to which they are
connected during measurement or test. Installation categories establish
standard impulse withstand voltage levels that commonly occur in
electrical distribution systems. The following is a description of installation
categories:
•
•
•
Installation Category I is for measurements performed on circuits not
directly connected to the electrical distribution system referred to as
MAINS3 voltage. This category is for measurements of voltages from
specially protected secondary circuits. Such voltage measurements
include signal levels, special equipment, limited-energy parts of
equipment, circuits powered by regulated low-voltage sources, and
electronics.
Installation Category II is for measurements performed on circuits
directly connected to the electrical distribution system. This category
refers to local-level electrical distribution, such as that provided by a
standard wall outlet (for example, 115 AC voltage for U.S. or 230 AC
voltage for Europe). Examples of Installation Category II are
measurements performed on household appliances, portable tools, and
similar devices.
Installation Category III is for measurements performed in the building
installation at the distribution level. This category refers to
measurements on hard-wired equipment such as equipment in fixed
installations, distribution boards, and circuit breakers. Other examples
are wiring, including cables, bus bars, junction boxes, switches, socket
1
2
3
Installation categories, also referred to as measurement categories, are defined in electrical safety standard IEC 61010-1.
Working voltage is the highest rms value of an AC or DC voltage that can occur across any particular insulation.
MAINS is defined as a hazardous live electrical supply system that powers equipment. Suitably rated measuring circuits may
be connected to the MAINS for measuring purposes.
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outlets in the fixed installation, and stationary motors with permanent
connections to fixed installations.
•
Installation Category IV is for measurements performed at the primary
electrical supply installation (<1,000 V). Examples include electricity
meters and measurements on primary overcurrent protection devices
and on ripple control units.
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1
Introduction
Thank you for buying an NI PCI-5911 digitizer, featuring the Flex ADC for
variable speed and resolution. This chapter contains information on
installing, connecting signals to, and acquiring data from the NI 5911
Installing the NI 5911
Installation involves the following main steps:
1. Install the NI-SCOPE driver software. You use this driver to write
programs to control the NI 5911 in different application development
environments (ADEs). Installing NI-SCOPE also allows you to
interactively control the NI 5911 with the Scope Soft Front Panel.
2. Install the NI 5911.
For step-by-step instructions for installing both NI-SCOPE and the
NI 5911, refer to the Where to Start with Your NI Digitizer document.
section of Appendix A, Specifications.
Connecting Signals
Figure 1-1 shows the front panel of the NI 5911. The front panel contains
three connectors—a BNC connector, an SMB connector, and a 9-pin
mini-circular DIN connector. Figure 1-2 shows the 9-pin mini-circular DIN
connector.
The BNC connector is for attaching the analog input signal you want to
measure. The BNC connector is analog input channel 0. To minimize noise,
do not allow the shell of the BNC cable to touch or lie near the metal of the
computer chassis. The SMB connector is used for external triggers and for
generating a probe compensation signal. The SMB connector is labeled
PFI 1. The DIN connector provides access to an additional external trigger
line. The DIN connector can be used to access PFI 2.
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Chapter 1
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Note The +5 V signal is fused at 1.1 A. However, NI recommends limiting the current
from this pin to 30 mA. The fuse is self-resetting.
CH 0
PFI 1
PFI 2
(DIN)
Figure 1-1. NI 5911 Connectors
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9
8
7
6
5
2
4
1
3
1
2
3
+5 V (Fused)
GND
Reserved
4
5
6
Reserved
Reserved
PFI 2
7
8
9
Reserved
Reserved
Reserved
Figure 1-2. 9-Pin Mini-Circular DIN Connector
Acquiring Data with the NI 5911
You can acquire data either programmatically—by writing an application
for the NI 5911—or interactively with the Scope Soft Front Panel.
Programmatically Controlling the NI 5911
To help you get started programming the NI 5911, NI-SCOPE includes
examples that you can use or modify.
You can find examples for the following ADEs in these locations:
•
•
•
LabVIEW—Go to Program Files\National Instruments\
LabVIEW\Examples\Instr\niScopeExamples\.
LabWindows™/CVI™, C, and Visual Basic with
Windows 2000/NT—Go to vxipnp\winnt\Niscope\Examples\.
LabWindows/CVI, C, and Visual Basic with Windows 98/95—Go to
vxipnp\win95\Niscope\Examples\c\.
For information on using NI-SCOPE to programmatically control your
is the NI-SCOPE Instrument Driver Quick Reference Guide, which
contains abbreviated information on the most commonly used functions
and LabVIEW VIs. For more detailed function reference help, refer to the
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Chapter 1
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NI-SCOPE Function Reference Help, located at Start»Programs»
National Instruments»NI-SCOPE. For more detailed VI help,
use LabVIEW context-sensitive help (Help»Show Context Help) or the
NI-SCOPE VI Reference Help, located at Start»Programs»National
Instruments»NI-SCOPE.
Interactively Controlling the NI 5911 with the Scope Soft Front Panel
The Scope Soft Front Panel allows you to interactively control the NI 5911
as you would a desktop oscilloscope. To launch the Scope Soft Front Panel,
select Start»Programs»National Instruments»NI-SCOPE»
NI-SCOPE Soft Front Panel. Refer to the Scope Soft Front Panel Help
for instructions on configuring the Scope Soft Front Panel for your specific
application.
Note Press <F1> while the Scope Soft Front Panel is running to access the Scope Soft
Front Panel Help.
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2
Hardware Overview
This chapter includes an overview of the NI 5911, explains the operation of
each functional unit making up the NI 5911, and describes the signal
connections. Figure 2-1 shows a block diagram of the NI 5911.
Analog Input
Connector
AC/DC Coupling
Protect/
Calibration
Mux
PGIA
A/D Converter
100 MHz, 8-Bit
Noise
Shaper
Calibration
Generator
Timing I/O,
Memory Control
Reference
Clock
Digital I/O
Connector
Digital Signal
Processor
Capture
Memory
Data
Figure 2-1. NI 5911 Block Diagram
Differential Programmable Gain Input Amplifier (PGIA)
The analog input of the NI 5911 is equipped with a differential
programmable gain input amplifier. The PGIA accurately interfaces to and
scales the signal presented to the ADC regardless of source impedance,
source amplitude, DC biasing, or common-mode noise voltages.
Differential Input
When measuring high dynamic range signals, ground noise is often a
problem. The PGIA of the NI 5911 allows you to make noise-free signal
measurements. The PGIA differential amplifier efficiently rejects any
noise present on the ground signal. Internal to the PGIA, the signal
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Chapter 2
Hardware Overview
presented at the negative input is subtracted from the signal presented at the
positive input. As shown in Figure 2-2, this subtraction removes ground
noise from the signal. The inner conductor of the BNC is V+. The outer
shell is V–.
Input Signal
V+
+
Vout
PGIA
–
V–
Ground Noise
Figure 2-2. Signal Noise-Free Measurements
Grounding Considerations
The path for the positive signal has been optimized for speed and linearity.
You should always apply signals to the positive input and ground to the
negative input. Reversing the inputs results in higher distortion and lower
bandwidth.
The negative input of the amplifier is grounded to PC ground through a
10 kΩ resistor. The PGIA is therefore referenced to ground, so it is not
necessary to make any external ground connections. If the device you
connect to the NI 5911 is already connected to ground, ground-loop noise
voltages may be induced into your system. Notice that in most of these
situations, the 10 kΩ resistance to PC ground is normally much higher than
the cable impedances you use. As a result, most of the noise voltage occurs
at the negative input of the PGIA where it is rejected, rather than in the
positive input, where it would be amplified.
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Input Ranges
To optimize the ADC resolution, you can select different gains for the
PGIA so that you can scale your input signal to match the full input range
of the converter. The NI 5911 PGIA offers seven input ranges, from 0.1 V
to 10 V, as shown in Table 2-1.
Table 2-1. Input Ranges for the NI 5911
Range
10 V
5 V
Input Protection Threshold
10 V
5 V
5 V
5 V
5 V
5 V
5 V
2 V
1 V
0.5 V
0.2 V
0.1 V
Note If you try to acquire a signal below the set input range, the sensitive front-end
components of the NI 5911 may become unstable and begin returning invalid data. To
return the digitizer to a stable configuration, switch to the maximum input range setting and
acquire an AC coupled or 0 V signal.
The input stage of the NI 5911 requires a settling time that depends on
which vertical range you are switching from and which vertical range you
are switching to. However, allowing for a delay of 250 ms between
configuring the input stage and starting the acquisition guarantees proper
settling.
Input Impedance
The input impedance of the NI 5911 PGIA is 1 MΩ between the positive
and negative input, 2% depending on input capacitance. The output
impedance of the device connected to the NI 5911 and the input impedance
of the NI 5911 form an impedance divider, which attenuates the input
signal according to the following formula:
VsRin
Vm = -------------------
Rs + Rin
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where Vm is the measured voltage, Vs is the source voltage, Rs is the external
source impedance, and Rin is the input impedance.
If the device you are measuring has a very large output impedance, your
measurements will be affected by this impedance divider. For example,
if the device has 1 MΩ output impedance, your measured signal is one-half
of the actual signal value.
Input Bias
The inputs of the PGIA typically draw an input bias current of 1 nA at
25 °C. Attaching a device with a very high source impedance can cause
an offset voltage to be added to the signal measured, according to
the formula Rs × 1 nA, where Rs is the external source impedance. For
example, if the device you have attached to the NI 5911 has an output
impedance of 10 kΩ, typically the offset voltage is 10 µV (10 kΩ × 1 nA).
Input Protection
The NI 5911 features input-protection circuits that protect both the positive
and negative analog inputs from damage from AC and DC signals up to
42 V.
If the voltage at one of these inputs exceeds a threshold voltage, Vtr, the
input clamps to Vtr and a resistance of 100 kΩ is inserted in the path to
minimize input currents to a nonharmful level.
The protection voltage, Vtr,is input range dependent, as shown in Table 2-1.
AC Coupling
When you measure a small AC signal on top of a large DC component, you
can use AC coupling. AC coupling rejects any DC component in your
signal before it enters into the PGIA. Activating AC coupling inserts a
capacitor in series with the input impedance. You can select input coupling
through software.
When changing the coupling on the digitizer, the input stage takes a finite
amount of time to settle. When switching from AC to DC coupling, the
settling time is approximately 0.5 ms. When switching from DC to
AC coupling, the returned data is accurate several time constants after
switching to AC. The NI 5911 has a time constant value of 68 ms. The
equation 1 – e–t/T, where T is the time constant, gives the percentage that the
original signal has settled after time t. Generally, six time constants is
enough time between switching to AC coupling and starting the acquisition
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Chapter 2
Hardware Overview
to allow an 8-bit digitizer to acquire accurate data. However, the NI 5911 in
flexible resolution mode is much more precise and thus requires a greater
number of time constants of settling time to achieve the desired precision.
Refer to Appendix A, Digitizer Basics, of the NI-SCOPE Software User
Manual, for more information on input coupling.
Conventional and Flexible Resolution Modes
In conventional mode, the NI 5911 works as a conventional desktop
oscilloscope, acquiring data at 100 MS/s with a vertical resolution of 8 bits.
This mode is useful for displaying waveforms and for deriving waveform
parameters such as slew rate, rise time, and settling time.
Flexible resolution mode differs from conventional mode in two ways: it
has higher resolution (sampling rate dependent), and the signal bandwidth
is limited to provide antialiasing protection. Flexible resolution mode is
useful for spectral analysis, distortion analysis, and other measurements for
which high resolution is crucial.
Conventional Mode
The ADC converts at a constant rate of 100 MS/s, but you can choose to
store only a fraction of these samples into memory at a lower rate. This
lower rate allows you to store waveforms using fewer data points and
decreases the burden of storing, analyzing, and displaying the waveforms.
If you need faster sampling rates, you can use Random Interleaved
Sampling (RIS) to effectively increase the sampling rate to 1 GS/s for
repetitive waveforms.
In conventional mode, all signals up to 100 MHz are passed to the ADC.
You must ensure that your signal is band-limited to prevent aliasing.
Aliasing and other sampling terms are described more thoroughly in the
NI-SCOPE Software User Manual.
Sampling Methods
Two sampling methods are available in conventional mode: real-time
sampling and random interleaved sampling (RIS). Using real-time
sampling, you can acquire data at a rate of 100/n MS/s, where n is a number
from 1 to 224. RIS sampling can be used on repetitive signals to effectively
extend the sampling rate above 100 MS/s. In RIS mode, you can sample at
rates of 100 × n MS/s, where n is a number from 2 to 10.
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Flexible Resolution Mode
Table 2-2 shows the relationship between the available sampling rates,
resolution, and the corresponding bandwidth for flexible resolution mode.
Table 2-2. Available Sampling Rates and Corresponding Bandwidth
in Flexible Resolution Mode
Sampling Rate
12.5 MS/s
5 MS/s
Resolution
11 bits
Bandwidth
3.75 MHz
2 MHz
14 bits
2.5 MS/s
1 MS/s
15.5 bits
17.5 bits
18 bits
1 MHz
400 kHz
200 kHz
80 kHz
40 kHz
20 kHz
8 kHz
500 kS/s
200 kS/s
100 kS/s
50 kS/s
18.5 bits
19 bits
19.5 bits
20.5 bits
21 bits
20 kS/s
10 kS/s
4 kHz
Like any other type of converter that uses noise shaping to enhance
resolution, the frequency response of the converter is only flat to its
maximum useful bandwidth. The NI 5911 has a bandwidth of 4 MHz.
Beyond this frequency, there is a span where the converter acts resonant
and where a signal is amplified before being converted. These signals are
attenuated in the subsequent digital filter to prevent aliasing. However,
if the applied signal contains major signal components in this frequency
range, such as harmonics or noise, the converter may overload and signal
data will be invalid. In this case, you receive an overload warning. You must
then either select a higher input range or attenuate the signal.
How Flexible Resolution Works
The ADC can be sourced through a noise shaping circuit that moves
quantization noise on the output of the ADC from lower frequencies to
higher frequencies. A digital lowpass filter applied to the data removes all
but a fraction of the original shaped quantization noise. The signal is then
resampled to a lower sampling frequency and a higher resolution. Flexible
resolution provides antialiasing protection due to the digital lowpass filter.
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Calibration
The NI 5911 can be calibrated for high accuracy and resolution because of
an advanced calibration scheme. There are two different types of
calibration: internal, or self-calibration, and external calibration. A third
option, internal restore, restores factory settings and should be used only in
the event of a self-calibration failure.
Self-calibration is performed using a software command that compensates
for drifts caused by environmental temperature changes. You can
self-calibrate the NI 5911 without any external equipment connected.
External calibration requires you to connect an external precision voltage
reference to the device. External calibration recalibrates the device when
the specified calibration interval has expired. Refer to Appendix A,
Specifications, for the calibration interval.
Self-Calibrating the NI 5911
You can self-calibrate the NI 5911 with a software function or a
LabVIEW VI. Refer to Chapter 3, Common Functions and Examples, of
the NI-SCOPE Software User Manual, for step-by-step instructions for
self-calibrating the NI 5911.
When Self-Calibration Is Needed
To provide the maximum accuracy independent of temperature changes,
the NI 5911 contains a heater that stabilizes the temperature of the most
sensitive circuitries on the board. However, the heater can accommodate
for temperature changes over a fixed range of 5 °C. When temperatures
exceed this range, the heater cannot stabilize the temperature, and signal
data becomes inaccurate. When the temperature range has been exceeded,
you receive a warning, and you must perform an internal calibration.
What Self-Calibration Does
Self-calibration performs the following operations:
•
The heater is set to regulate over a range of temperatures centered at
the current environmental temperature. The circuit components require
time to stabilize at the new temperature. This temperature stabilization
accounts for the majority of the calibration time. Refer to the
Calibration section of Appendix A, Specifications, for more
information.
•
Gain and offset are calibrated for each individual input range.
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•
•
The linearity of the ADC is calibrated using an internal sine wave
generator as reference.
The time-to-digital converter used for RIS measurements is calibrated.
Caution Do not apply high-amplitude or high-frequency signals to the NI 5911 during
self-calibration. For optimal calibration performance, disconnect the input signal from the
NI 5911.
Why Warnings Occur During Acquisition
The NI 5911 uses a heater circuit to maintain constant temperature on the
critical circuitry used in flexible resolution mode. If this circuit cannot
maintain the temperature within specification, a warning is generated. This
warning indicates that the temperature of the ADC is out of range and
should be recalibrated with a self-calibration. During acquisition in flexible
resolution mode, a warning is generated if the input to the ADC goes out of
range for the converter. The fact that this condition has occurred may not
be obvious from inspecting the data because of the digital filtering that
takes place on the acquired data. Therefore, a warning occurs to notify you
that the data includes some samples that were out of the range of the
converter and may be inaccurate.
External Calibration
External calibration calibrates the internal reference on the NI 5911.
The NI 5911 is already calibrated when it is shipped from the factory.
Periodically, the NI 5911 needs external calibration to remain within
the specified accuracy. For more information on calibration, contact NI, or
visit ni.com/calibration. For actual intervals and accuracy, refer to
the Calibration section of Appendix A, Specifications.
Triggering and Arming
There are several triggering methods for the NI 5911. The trigger can be an
analog level that is compared to the input or any of several digital inputs.
You also can call a software function to trigger the digitizer. Figure 2-3
shows the different trigger sources. When you use a digital signal, that
signal must be at a high TTL level for at least 40 ns before any triggers are
accepted.
Note The NI 5911 does not support delayed triggering.
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Analog
Input
High
Level
+
COMP
Gain
Analog
Trigger
Circuit
ATC_OUT
COMP
–
Low
Level
a. Analog Trigger Circuit
Software
ATC_OUT
RTSI<0..6>
Trigger
Arm
7
2
PFI 1, PFI 2
b. Trigger and Arm Sources
Figure 2-3. Trigger Sources
Analog Trigger Circuit
The analog trigger on the NI 5911 operates by comparing the current
analog input to an onboard threshold voltage. This threshold voltage is the
trigger value, and can be set within the current input range in 170 steps.
Therefore, for a 10 V input range, the trigger can be set in increments of
20 V/170 = 118 mV. A hysteresis value may also be associated with the
trigger that can be set in the same size increments. The hysteresis value
creates a trigger window the signal must pass through before the trigger is
accepted. You can generate triggers on a rising or falling edge condition.
For more information on triggering, refer to Chapter 3, Common Functions
and Examples, of the NI-SCOPE Software User Manual.
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Trigger Holdoff
Trigger holdoff is the minimum length of time (in seconds) from an
accepted trigger to the start of the next record. In other words, when a
trigger is accepted, the trigger counter is loaded with the desired holdoff
time. After completing its current record, the digitizer records no data and
accepts no triggers until the holdoff counter runs out. When the counter
runs out, the next record begins and a trigger may be accepted. Setting a
holdoff time shorter than posttrigger acquisition time has no effect, as
triggers are always rejected during an acquisition.
Note Time to acquire posttrigger samples is calculated by the following formula:
(posttrigger samples)/(sample rate).
Trigger holdoff is provided in hardware using a 32-bit counter clocked by a
25 MHz internal timebase. With this configuration, you can select
a hardware holdoff value of 5 µs to 171.79 s in increments of 40 ns. For
more information on trigger holdoff, refer to Chapter 3, Common Functions
and Examples, of the NI-SCOPE Software User Manual.
Memory
The NI 5911 allocates at least 4 kB of onboard memory for each record in
a single multi-record acquisition. Samples are stored in this buffer before
transfer to the host computer. Thus the minimum size for a buffer in the
onboard memory is approximately 4,000 8-bit conventional mode samples
or 1,000 32-bit flexible resolution mode samples. Software allows you to
specify buffers of less than these minimum buffer sizes because only the
specified number of points is transferred from onboard memory into the
memory of the host computer.
The total number of samples that can be stored depends on the size of the
acquisition memory module installed on the NI 5911 and the size of each
acquired sample. The maximum number of records in a single multi-record
acquisition is equal to the size of the memory module divided by 4 kB.
Triggering and Memory Usage
During the acquisition, samples are stored in a circular buffer that is
continually rewritten until a trigger is received. After the trigger is
received, the NI 5911 continues to acquire posttrigger samples if you have
specified a posttrigger sample count. The acquired samples are placed into
onboard memory. The number of posttrigger or pretrigger samples is only
limited by the amount of onboard memory.
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Multi-Record Acquisitions
After the trigger has been received and the posttrigger samples have been
stored, the NI 5911 can be configured to begin another acquisition that is
stored in another onboard memory record. This operation is a multi-record
acquisition. To perform multi-record acquisitions, configure the NI 5911 to
the number of records you want to acquire before starting the acquisition.
The NI 5911 acquires an additional record each time a trigger is accepted
until all the requested records are stored in memory. You may acquire up
to 1,024 records if your NI 5911 is equipped with 4 MB of onboard
memory, or 4,096 records with 16 MB of onboard memory. Software
intervention after the initial setup is not required.
Multi-record acquisitions can quickly acquire numerous triggered
waveforms because they allow hardware rearming of the digitizer before
the data is fetched. Therefore the dead time, or the time when the digitizer
is not ready for a trigger, is extremely small.
For more information on multi-record acquisitions and dead time, refer to
Chapter 5, Tasks and Examples, of the NI-SCOPE Software User Manual.
RTSI Bus and Clock PFI
The Real-Time System Integration (RTSI) bus allows NI digitizers to
synchronize timing and triggering on multiple devices. The RTSI bus has
seven bidirectional trigger lines and one bidirectional clock signal.
You can program any of the seven trigger lines to provide or accept a
synchronous trigger signal. You can also use any of the RTSI trigger lines
to provide a synchronization pulse from a master device if you are
synchronizing multiple NI 5911 devices.
You can use the RTSI bus clock line to provide or accept a 10 MHz
reference clock to synchronize multiple NI 5911 devices.
PFI Lines
The NI 5911 has two digital lines that can accept a trigger, accept or
generate a reference clock, or output a 1 kHz square wave. The function of
each PFI line is independent. However, only one trigger source can be
accepted during acquisition.
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PFI Lines as Inputs
You can select PFI 1 or PFI 2 as inputs for a trigger or a reference clock.
Refer to the Synchronization section for more information about the use of
reference clocks in the NI 5911.
PFI Lines as Outputs
You can select PFI 1 or PFI 2 to output several digital signals.
Reference Clock is a 10 MHz clock that is synchronous to the 100 MHz
sample clock on the NI 5911. You can use the Reference Clock to
synchronize to another NI 5911 configured as a slave device or to other
equipment that can accept a 10 MHz reference.
Frequency Output is a 1 kHz digital pulse train signal with a 50% duty
cycle. The most common application of Frequency Output for the NI 5911
is to provide a signal for compensating a passive probe.
Synchronization
The NI 5911 uses a digital phase-locked loop to synchronize the 100 MHz
sample clock to a 10 MHz reference. This reference frequency can be
supplied by an internal crystal oscillator or through an external frequency
input through the RTSI bus clock line or a PFI input.
The NI 5911 can also output its 10 MHz reference on the RTSI bus clock
line or a PFI line so that additional NI 5911 devices or other equipment can
be synchronized to the same reference.
While the reference clock input is sufficient to synchronize the 100 MHz
sample clocks, it is also necessary to synchronize clock dividers on each
NI 5911 so that internal clock divisors are synchronized on each device.
These lower frequencies are important because they are used to determine
trigger times and sample position.
To synchronize the NI 5911 clock dividers, you must connect the digitizers
with an RTSI bus cable. One of the RTSI bus triggers must be designated
as a synchronization line. This line is an output from the master device and
sent from the master NI 5911 to the slaves. This pulse supplies the slave
devices with a reference time to clear their clock dividers. Hardware arming
cannot be used during an acquisition using multiple devices.
To synchronize the triggers of multiple NI 5911 devices, one digitizer must
receive a trigger as described in the Triggering and Arming section and then
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route that trigger over the RTSI bus to trigger the other digitizer(s).
However, the trigger that is routed to the other digitizer(s) is sent
synchronously to an internal 25 MHz clock. For more information about
synchronization, refer to the NI-SCOPE Software User Manual.
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A
Specifications
This appendix lists the specifications of the NI 5911. These specifications
are typical at 25 °C unless otherwise stated.
Acquisition System
Bandwidth .............................................. 100 MHz maximum;
refer to Table 2-2, Available
Sampling Rates and
Corresponding Bandwidth in
Flexible Resolution Mode
Number of channels ............................... 1
Number of flexible resolution ADC....... 1
Max RIS sample rate.............................. 1 GS/s
Max real-time sample rate...................... 100 MS/s
Resolution
Sample Rate
100/n* MS/s
12.5 MS/s
5 MS/s
Mode
Effective Resolution
8 bits
Conventional
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
11 bits
14 bits
2.5 MS/s
1 MS/s
15.5 bits
17.5 bits
18 bits
500 kS/s
200 kS/s
18.5 bits
19 bits
100 kS/s
50 kS/s
19.5 bits
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Appendix A
Specifications
Sample Rate
20 kS/s
10 kS/s
Mode
Effective Resolution
20.5 bits
Flexible Resolution
Flexible Resolution
21 bits
* 1 ≤ n ≤ 224 in conventional mode
Sample onboard memory........................4 MB or 16 MB
Memory Sample Depth
Sampling
Frequency
Sample Depth
(4 MB)
Sample Depth
(16 MB)
Mode
100/n* MS/s
Conventional
4 MS
1 MS
16 MS
4 MS
12.5 MS/s
Flexible
Resolution
5 MS/s
Flexible
Resolution
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
2.5 MS/s
1 MS/s
Flexible
Resolution
Flexible
Resolution
500 kS/s
200 kS/s
100 kS/s
50 kS/s
20 kS/s
10 kS/s
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
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Appendix A
Specifications
Vertical Sensitivity (Input Ranges)
Input Range
10 V
Noise Referred to Input
–174 dBfs/ Hz
–168 dBfs/ Hz
–160 dBfs/ Hz
–154 dBfs/ Hz
–148 dBfs/ Hz
–140 dBfs/ Hz
–128 dBfs/ Hz
5 V
2 V
1 V
0.5 V
0.2 V
0.1 V
Acquisition Characteristics
Accuracy
DC gain accuracy................................... 0.05% signal 0.0001% fs
for all input ranges at 1 MS/s
in flexible resolution mode
DC offset accuracy................................. 0.1 mV 0.01% fs
for all input ranges at 1 MS/s
in flexible resolution mode
Input coupling ........................................ DC and AC, software selectable
AC coupling cut-off frequency
(–3 dB) ................................................... 2.5 Hz 0.5 Hz
Input impedance..................................... 1 MΩ 2%
Max measurable input voltage ............... 10 V (DC + peak AC)
Input protection...................................... 42 VDC (DC + peak AC)
Input bias current ................................... 1 nA, typical at 25 °C
Common-Mode Characteristics
Impedance to chassis ground ................. 10 kΩ
Common-mode rejection ratio ............... CMRR > –70 dB, (Fin < 1 kHz)
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Appendix A
Specifications
Filtering
Sampling Frequency
100/n* MS/s
Filter Mode
Bandwidth
100 MHz
Ripple
3 dB
Alias Attenuation
N/A
Conventional
12.5 MS/s
Flexible
3.75 MHz
0.2 dB
–60 dB
Resolution
5 MS/s
2.5 MS/s
1 MS/s
Flexible
Resolution
2 MHz
1 MHz
400 kHz
200 kHz
80 kHz
40 kHz
20 kHz
8 kHz
0.1 dB
–70 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
Flexible
Resolution
0.05 dB
Flexible
Resolution
0.005 dB
0.005 dB
0.005 dB
0.005 dB
0.005 dB
0.005 dB
0.005 dB
500 kS/s
200 kS/s
100 kS/s
50 kS/s
20 kS/s
10 kS/s
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
4 kHz
Resolution
* 1 ≤ n ≤ 224 in conventional mode
Dynamic Range
Noise (excluding input-referred noise)
Sampling Frequency
100/n* MS/s
12.5 MS/s
Bandwidth
100 MHz
3.75 MHz
2 MHz
Noise Density
–120 dBfs/ Hz
–135 dBfs/ Hz
–143 dBfs/ Hz
–152 dBfs/ Hz
Total Noise
–43 dBfs
–64 dBfs
–83 dBfs
–91 dBfs
5 MS/s
2.5 MS/s
1 MHz
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Appendix A
Specifications
Sampling Frequency
Bandwidth
400 kHz
200 kHz
80 kHz
Noise Density
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
Total Noise
1 MS/s
–104 dBfs
–107 dBfs
–111 dBfs
–114 dBfs
–117 dBfs
–121 dBfs
–124 dBfs
500 kS/s
200 kS/s
100 kS/s
40 kHz
50 kS/s
20 kS/s
20 kHz
8 kHz
10 kS/s
4 kHz
* 1 ≤ n ≤ 224 in conventional mode
Distortion
Sampling
SFDR for Input
SFDR for Input
SFDR for Input
Frequency
0 dBfs
50 dBfs
65 dBfs
70 dBfs
75 dBfs
85 dBfs
90 dBfs
100 dBfs
100 dBfs
100 dBfs
100 dBfs
100 dBfs
–20 dBfs
–60 dBfs (typical)
100 MS/s
12.5 MS/s
5 MS/s
50 dBfs
N/A
85 dBfs
125 dBfs
130 dBfs
135 dBfs
145 dBfs
150 dBv
160 dBfs
160 dBfs
160 dBfs
160 dBfs
160 dBfs
90 dBfs
2.5 MS/s
1 MS/s
95 dBfs
105 dBfs
110 dBfs
110 dBfs
110 dBfs
110 dBfs
110 dBfs
110 dBfs
500 kS/s
200 kS/s
100 kS/s
50 kS/s
20 kS/s
10 kS/s
Timebase System
Reference clock...................................... 10 MHz
Clock accuracy (as master) .................... 10 MHz 50 ppm
Clock input tolerance (as slave)............. 10 MHz 100 ppm
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Appendix A
Specifications
Clock jitter ..............................................<75 pSrms, independent of
reference clock source
Clock compatibility ................................TTL for both input and output
Sampling clock frequencies
Conventional mode....................... 100/n MHz, where 1 ≤ n ≤224
Flexible resolution mode.................12.5 MHz, 5 MHz, 2.5 MHz,
1 MHz, 500 kHz, 200 kHz,
100 kHz, 50 kHz, 20 kHz, 10 kHz
Reference clock sources .........................PFI lines, RTSI clock, or onboard
Triggering Systems
Modes .....................................................Edge, hysteresis, window, digital
Source .....................................................CH0, RTSI<0..6>, PFI 1, 2
Slope .......................................................Rising/falling
Hysteresis................................................Full-scale voltage/n, where n is
between 1 and 170
Coupling .................................................AC/DC
Pretrigger depth ......................................Up to 4 MS or 16 MS, depending
on memory option purchased and
sampling mode
Posttrigger depth.....................................Up to 4 MS or 16 MS, depending
on memory option purchased and
sampling mode
Holdoff time ...........................................5 µs to 171.79 s in increments
of 40 ns
Trigger resolution ...................................170 steps in full-scale voltage
range
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Appendix A
Specifications
Sampling Methods
Random interleaved sampling................ 1 GS/s down to 200 MS/s
effective sample rate, repetitive
signals only
Real-time sampling ................................ Up to 100 MS/s sample rate for
transient and repetitive signals
Power Requirements
+5 VDC.................................................. 4 A
+12 VDC................................................ 100 mA
–12 VDC ................................................ 100 mA
Physical
Dimensions............................................. 33.8 by 9.9 cm (13.3 by 3.9 in.)
I/O connectors
Analog input CH0........................... BNC female
Digital triggers ................................ SMB female, 9-pin mini DIN
Operating Environment
Note Multiple NI 5911 devices in the same computer may raise operating temperatures
beyond specification and give rise to imprecise data. NI strongly recommends leaving an
empty PCI slot between multiple NI 5911 devices or adding a fan.
Ambient temperature.............................. 5 °C to 40 °C
Relative humidity................................... 10% to 90%, noncondensing
Storage Environment
Ambient temperature.............................. –20 °C to 65 °C
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Appendix A
Specifications
Calibration
Self-calibration (internal calibration) .....Self-calibration is done using a
software command. The
calibration involves gain, offset
and linearity correction for all
input ranges and input modes.
Interval.............................................1 week, or any time temperature
changes beyond 5 °C. Hardware
detects temperature variations
beyond calibration limits, which
can also be queried by software.
External calibration.................................Internal reference requires
recalibration
Interval.............................................1 year
Warm-up time.........................................15 minutes
Safety
This product is designed to meet the requirements of the following
standards of safety for electrical equipment for measurement, control and
laboratory use:
•
•
•
IEC 61010-1, EN 61010-1
UL 3111-1, UL 61010B-1
CAN/CSA C22.2 No. 1010.1
Note For UL and other safety certifications, refer to the product label or to ni.com.
Electromagnetic Compatibility
Emissions................................................EN 55011 Class A at 10 m
FCC Part 15A above 1 GHz
Immunity ................................................EN 61326:1997 + A2:2001,
Table 1
EMC/EMI ...............................................CE, C-Tick and FCC Part 15
(Class A) Compliant
Note For EMC compliance, operate this device with shielded cabling.
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Appendix A
Specifications
CE Compliance
This product meets the essential requirements of applicable European
Directives, as amended for CE Marking, as follows:
•
•
Low-Voltage Directive (safety):73/23/EEC
Electromagnetic Compatibility Directive (EMC):89/336/EEC
Note Refer to the Declaration of Conformity (DoC) for this product for any additional
regulatory compliance information. To obtain the DoC for this product, click Declarations
of Conformity Information at ni.com/hardref.nsf/.
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B
Technical Support and
Professional Services
Visit the following sections of the National Instruments Web site at
ni.comfor technical support and professional services:
•
Support—Online technical support resources include the following:
–
Self-Help Resources—For immediate answers and solutions,
visit our extensive library of technical support resources available
in English, Japanese, and Spanish at ni.com/support. These
resources are available for most products at no cost to registered
users and include software drivers and updates, a KnowledgeBase,
product manuals, step-by-step troubleshooting wizards,
conformity documentation, example code, tutorials and
application notes, instrument drivers, discussion forums,
a measurement glossary, and so on.
–
Assisted Support Options—Contact NI engineers and other
measurement and automation professionals by visiting ni.com/
support. Our online system helps you define your question and
connects you to the experts by phone, discussion forum, or email.
•
•
Training—Visit ni.com/custedfor self-paced tutorials, videos, and
interactive CDs. You also can register for instructor-led, hands-on
courses at locations around the world.
System Integration—If you have time constraints, limited in-house
technical resources, or other project challenges, NI Alliance Program
members can help. To learn more, call your local NI office or visit
ni.com/alliance.
•
Declaration of Conformity (DoC)—A DoC is our claim of
compliance with the Council of the European Communities using the
manufacturer’s declaration of conformity. This system affords the user
protection for electronic compatibility (EMC) and product safety. You
can obtain the DoC for your product by visiting ni.com/
hardref.nsf.
•
can obtain the calibration certificate for your product at ni.com/
calibration.
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Appendix B
Technical Support and Professional Services
If you searched ni.comand could not find the answers you need, contact
your local office or NI corporate headquarters. Phone numbers for our
worldwide offices are listed at the front of this manual. You also can visit
the Worldwide Offices section of ni.com/niglobalto access the branch
office Web sites, which provide up-to-date contact information, support
phone numbers, email addresses, and current events.
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Glossary
Symbol
Prefix
pico
Value
10–12
10–9
10– 6
10–3
103
p
n
nano
micro
milli
kilo
µ
m
k
M
G
mega
giga
106
109
Symbols
%
+
–
/
percent
positive of, or plus
negative of, or minus
per
°
degree
plus or minus
ohm
Ω
A
A
amperes
A/D
AC
analog to digital
alternating current
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Glossary
AC coupled
ADC
the passing of a signal through a filter network that removes the
DC component of the signal
analog-to-digital converter—an electronic device, often an integrated
circuit, that converts an analog voltage to a digital number
ADC resolution
the resolution of the ADC, which is measured in bits. An ADC with16 bits
has a higher resolution, and thus a higher degree of accuracy, than a 12-bit
ADC.
alias
a false lower frequency component that appears in sampled data acquired
at too low a sampling rate
amplification
amplitude flatness
attenuate
a type of signal conditioning that improves accuracy in the resulting
digitized signal and reduces noise
a measure of how close to constant the gain of a circuit remains over a range
of frequencies
to reduce in magnitude
B
b
bit—one binary digit, either 0 or 1
B
byte—eight related bits of data, an eight-bit binary number. Also used
to denote the amount of memory required to store one byte of data.
bandwidth
the range of frequencies present in a signal, or the range of frequencies to
which a measuring device can respond
buffer
bus
temporary storage for acquired or generated data (software)
the group of conductors that interconnect individual circuitry in a computer.
Typically, a bus is the expansion vehicle to which I/O or other devices are
connected. Examples of PC buses are the PCI and ISA bus.
C
C
Celsius
channel
pin or wire lead to which you apply or from which you read the analog or
digital signal
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clock
hardware component that controls timing for reading from or writing to
groups
CMRR
common-mode rejection ratio—a measure of an instrument’s ability to
reject interference from a common-mode signal, usually expressed in
decibels (dB)
counter/timer
coupling
a circuit that counts external pulses or clock pulses (timing)
the manner in which a signal is connected from one location to another
D
dB
decibel—the unit for expressing a logarithmic measure of the ratio of
two signal levels: dB = 20log10 V1/V2, for signals in volts
DC
direct current
default setting
a default parameter value recorded in the driver. In many cases, the default
input of a control is a certain value (often 0) that means use the current
default setting.
device
A plug-in data acquisition device, card, or pad that can contain multiple
channels and conversion devices. Plug-in devices, PCMCIA cards, and
devices such as the DAQPad-1200, which connects to your computer
parallel port, are all examples of DAQ devices. SCXI modules are distinct
from devices, with the exception of the SCXI-1200, which is a hybrid. The
NI 5911 is an example of a device.
differential input
double insulated
drivers
an analog input consisting of two terminals, both of which are isolated from
computer ground, whose difference is measured
a device that contains the necessary insulating structures to provide electric
shock protection without the requirement of a safety ground connection
software that controls a specific hardware instrument
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Glossary
E
EEPROM
electrically erasable programmable read-only memory—ROM that can be
erased with an electrical signal and reprogrammed
equivalent time
sampling
any method used to sample signals in such a way that the apparent sampling
rate is higher than the real sampling rate
event
the condition or state of an analog or digital signal
F
filtering
a type of signal conditioning that allows you to filter unwanted signals from
the signal you are trying to measure
fs
full-scale—total voltage in the input range. A 10 V input range is 20 V fs
G
gain
the factor by which a signal is amplified, sometimes expressed in decibels
H
hardware
the physical components of a computer system, such as the circuit boards,
plug-in boards, chassis, enclosures, peripherals, cables, and so on
harmonics
Hz
multiples of the fundamental frequency of a signal
hertz—per second, as in cycles per second or samples per second
I
I/O
input/output—the transfer of data to/from a computer system involving
communications channels, operator interface devices, and/or data
acquisition and control interfaces
inductance
the relationship of induced voltage to current
the current that flows into the inputs of a circuit
input bias current
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Glossary
input impedance
instrument driver
the measured resistance and capacitance between the input terminals of a
circuit
a set of high-level software functions that controls a specific plug-in DAQ
board. Instrument drivers are available in several forms, ranging from a
function callable language to a virtual instrument (VI) in LabVIEW.
interrupt
a computer signal indicating that the CPU should suspend its current task
to service a designated activity
interrupt level
ISA
the relative priority at which a device can interrupt
industry standard architecture
K
k
kilo—the standard metric prefix for 1,000, or 103, used with units of
measure such as volts, hertz, and meters
kS
1,000 samples
L
LabVIEW
laboratory virtual instrument engineering workbench—a graphical
programming ADE developed by National Instruments
LSB
least significant bit
M
m
meters
MB
megabytes of memory
See buffer.
memory buffer
MS
million samples
most significant bit
MSB
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Glossary
N
noise
an undesirable electrical signal—noise comes from external sources such
as the AC power line, motors, generators, transformers, fluorescent lights,
soldering irons, CRT displays, computers, electrical storms, welders, radio
transmitters, and internal sources such as semiconductors, resistors, and
capacitors. Noise corrupts signals you are trying to send or receive.
Nyquist frequency
a frequency that is one-half the sampling rate. See also Nyquist Sampling
Theorem.
Nyquist Sampling
Theorem
the theorem states that if a continuous bandwidth-limited analog signal
contains no frequency components higher than half the frequency at which
it is sampled, then the original signal can be recovered without distortion.
O
Ohm’s Law
(R = V/I)—the relationship of voltage to current in a resistance
overrange
a segment of the input range of an instrument outside of the normal
measuring range. Measurements can still be made, usually with a
degradation in specifications.
oversampling
sampling at a rate greater than the Nyquist frequency
P
passband
the frequency range that a filter passes without attenuation
PCI
Peripheral Component Interconnect—a high-performance expansion bus
architecture originally developed by Intel to replace ISA and EISA; it is
achieving widespread acceptance as a standard for PCs and workstations
and offers a theoretical maximum transfer rate of 132 Mbytes/s
peak value
the absolute maximum or minimum amplitude of a signal (AC + DC)
posttriggering
the technique to acquire a programmed number of samples after trigger
conditions are met
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Glossary
pretriggering
PXI
the technique used on a device to keep a buffer filled with data, so that when
the trigger conditions are met, the sample includes the data leading up
to the trigger condition
PCI eXtensions for Instrumentation. PXI is an open specification that
builds off the CompactPCI specification by adding
instrumentation-specific features.
R
R
resistor
RAM
random-access memory
sampling that occurs immediately
real-time sampling
random interleaved
sampling (RIS)
method of increasing the sample rate by repetitively sampling a repeated
waveform
resolution
the smallest signal increment that can be detected by a measurement
system. Resolution can be expressed in bits or in digits. The number of bits
in a system is roughly equal to 3.3 times the number of digits.
rms
root mean square—a measure of signal amplitude; the square root of the
average value of the square of the instantaneous signal amplitude
ROM
read-only memory
RTSI bus
real-time system integration bus—the National Instruments timing bus that
connects devices directly, by means of connectors on top of the boards, for
precise synchronization of functions
S
s
seconds
samples
S
S/s
samples per second—used to express the rate at which an instrument
samples an analog signal. 100 MS/s would equal 100 million samples each
second.
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Glossary
sense
in four-wire resistance the sense measures the voltage across the resistor
being excited by the excitation current
settling time
source impedance
the amount of time required for a voltage to reach its final value within
specified limits
a parameter of signal sources that reflects current-driving ability of voltage
sources (lower is better) and the voltage-driving ability of current sources
(higher is better)
system noise
a measure of the amount of noise seen by an analog circuit or an ADC when
the analog inputs are grounded
T
temperature
coefficient
the percentage that a measurement will vary according to temperature.
See also thermal drift.
thermal drift
measurements that change as the temperature varies
thermal EMFs
thermal electromotive forces—voltages generated at the junctions of
dissimilar metals that are functions of temperature. Also called
thermoelectric potentials.
thermoelectric
potentials
See thermal EMFs.
transfer rate
the rate, measured in bytes/s, at which data is moved from source to
destination after software initialization and set up operations; the maximum
rate at which the hardware can operate
trigger
any event that causes or starts some form of data capture
U
undersampling
sampling at a rate lower than the Nyquist frequency—can cause aliasing
the number of output updates per second
update rate
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V
V
volts
VAC
VDC
Verror
VI
volts alternating current
volts direct current
voltage error
virtual instrument—(1) a combination of hardware and/or software
elements, typically used with a PC, that has the functionality of a classic
stand-alone instrument (2) a LabVIEW software module (VI), which
consists of a front panel user interface and a block diagram program
Vrms
volts, root mean square value
W
waveform shape
the shape the magnitude of a signal creates over time
working voltage
the highest voltage that should be applied to a product in normal use,
normally well under the breakdown voltage for safety margin
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Index
location on front panel (figure), 1-2
SMB connector, 1-1
contacting National Instruments, B-2
A
AC coupling, 2-4
accuracy characteristics, A-3
acquisition
multiple record, 2-11
Scope Soft Front Panel, 1-4
acquisition characteristics specifications
accuracy, A-3
common-mode characteristics, A-3
distortion, A-5
dynamic range, A-4
dead time, in multiple record acquisition, 2-11
Declaration of Conformity, B-1
diagnostic resources, B-1
differential programmable gain input amplifier
(PGIA)
filtering, A-4
acquisition modes specifications, A-7
acquisition system specifications, A-1
analog trigger circuit, 2-9
B
AC coupling, 2-4
differential input, 2-1
input bias, 2-4
input impedance, 2-3
bias, input, 2-4
BNC connector, 1-1
input protection, 2-4
input ranges, 2-3
noise-free signal measurement (figure), 2-2
DIN connector, 1-1
distortion specifications, A-5
documentation
online library, B-1
related documentation, viii
drivers
C
calibration
errors occurring during acquisition, 2-8
external calibration, 2-8
internal calibration, 2-7
specifications, A-8
calibration certificate, B-1
clock lines, 2-12
common-mode characteristics, A-3
connectors
instrument, B-1
software, B-1
dynamic range specifications, A-4
BNC connector, 1-1
DIN connector, 1-1
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RTSI bus trigger and clock lines, 2-11
trigger holdoff, 2-10
triggering and arming
E
errors during acquisition, 2-8
analog trigger circuit, 2-9
trigger holdoff, 2-10
trigger sources (figure), 2-9
F
filtering specifications, A-4
flexible resolution mode
available sampling rates (table), 2-6
definition, 2-6
purpose and use, 2-6
frequently asked questions, B-1
I
impedance
formula for impedance divider, 2-3
input and output impedance, 2-3
input bias, 2-4
G
grounding considerations, 2-2
input impedance, 2-3
input protection circuits, 2-4
input ranges, 2-3
H
installation
hardware overview
category, ix
See also specifications
acquisition system
installing NI 5911, 1-1
instrument drivers, B-1
calibration, 2-7
amplifier (PGIA)
AC coupling, 2-4
differential input, 2-1
input bias, 2-4
input impedance, 2-3
input ranges, 2-3
memory
description, 2-10
triggering and memory usage, 2-10
noise-free signal measurement
(figure), 2-2
flexible resolution mode, 2-6
memory, 2-10
multiple record acquisition, 2-11
oscilloscope mode, 2-5
N
National Instruments
calibration certificate, B-1
customer education, B-1
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Declaration of Conformity, B-1
professional services, B-1
system integration services, B-1
technical support, B-1
P
PFI lines
as inputs, 2-12
as outputs, 2-12
overview, 2-11
worldwide offices, B-2
NI 5911
input amplifier (PGIA)
phone technical support, B-2
professional services, B-1
differential programmable gain input
See also hardware overview
block diagram, 2-1
connectors
BNC connector, 1-1
DIN connector, 1-1
location on front panel (figure), 1-2
SMB connector, 1-1
front panel (figure), 1-2
installing, 1-1
Scope Soft Front Panel, 1-4
specifications
acquisition characteristics, A-3
acquisition modes, A-7
triggering systems, A-6
NI-SCOPE driver software
installing, 1-1
Random Interleaved Sampling (RIS), 2-5
related documentation, viii
RIS (Random Interleaved Sampling), 2-5
RTSI bus trigger and clock lines
PIF lines, 2-11
NI 5911, 1-3
purpose and use, 2-11
noise-free measurements, 2-1
synchronization, 2-12
O
online technical support, B-1
oscilloscope mode
sampling methods—real-time and RIS, 2-5
sampling rate, flexible resolution mode
(table), 2-6
definition, 2-5
purpose and use, 2-5
Real-Time and RIS sampling
methods, 2-5
Scope Soft Front Panel, 1-4
SMB connector, 1-1
software drivers, B-1
output impedance, 2-3
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Index
specifications
acquisition characteristics
telephone technical support, B-2
timebase system specifications, A-5
training
accuracy, A-3
common-mode characteristics, A-3
distortion, A-5
dynamic range, A-4
filtering, A-4
customer, B-1
triggering and arming
analog trigger circuit, 2-9
memory usage, 2-10
specifications, A-6
trigger holdoff, 2-10
trigger sources (figure), 2-9
acquisition modes, A-7
acquisition system, A-1
calibration, A-8
operating environment, A-7
physical, A-7
power requirements, A-7
storage environment, A-7
timebase system, A-5
triggering systems, A-6
storage environment specifications, A-7
support
technical, B-1
synchronization, 2-12
system integration services, B-1
Web
professional services, B-1
technical support, B-1
worldwide technical support, B-2
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