Zebra Technologies Printer GC420t User Manual

®
Zebra GC420t™  
Desktop Thermal Printer  
User Guide  
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iii  
©2012 ZIH Corp. GC420, GC420t, ZBI, ZBI 2.0, ZBI-Developer, Uni-Ribbon,  
ZebraDesigner, ZebraNet, EPL, EPL2, ZPL, ZPL II and all product names and numbers  
are Zebra trademarks, and Zebra, the Zebra head graphic, ZPL, ZPL II, Element Energy  
Equalizer circuit, E3 Circuit and, and ZebraNet are registered trademarks of ZIH Corp. All  
rights reserved. All other trademarks are the property of their respective owners.  
This product may contain ZPL®, ZPL II®, and ZebraLink™ programs; Element Energy  
Equalizer™ Circuit; E3®; and Monotype Imaging fonts. Software ©ZIH corp. All rights  
reserved worldwide.  
All rights reserved worldwide.Monotype®, Intellifont® and UFST® are trademarks of  
Monotype Imaging, Inc. registered in the United States Patent and Trademark Office and  
may be registered in certain jurisdictions.  
CG Triumvirate is a trademark of Monotype Imaging, Inc. and may be registered in some  
jurisdictions.  
TrueType® is a trademark of Apple Computer, Inc. registered in the United States Patent  
and Trademark Office and may be registered in certancertain jurisdictions.  
Proprietary Statement  
This manual contains proprietary information of Zebra Technologies Corporation and its  
subsidiaries (“Zebra Technologies”). It is intended solely for the information and use of  
parties operating and maintaining the equipment described herein. Such proprietary  
information may not be used, reproduced, or disclosed to any other parties for any other  
purpose without the express written permission of Zebra Technologies.  
Product Improvements  
Continuous improvement of products is a policy of Zebra Technologies. All specifications  
and designs are subject to change without notice.  
Liability Disclaimer  
Zebra Technologies takes steps to ensure that its published Engineering specifications and  
manuals are correct; however, errors do occur. Zebra Technologies reserves the right to  
correct any such errors and disclaims liability resulting therefrom.  
Limitation of Liability  
In no event shall Zebra Technologies or anyone else involved in the creation, production,  
or delivery of the accompanying product (including hardware and software) be liable for  
any damages whatsoever (including, without limitation, consequential damages including  
loss of business profits, business interruption, or loss of business information) arising out  
of the use of, the results of use of, or inability to use such product, even if Zebra  
Technologies has been advised of the possibility of such damages. Some jurisdictions do  
not allow the exclusion or limitation of incidental or consequential damages, so the above  
limitation or exclusion may not apply to you.  
Canadian DOC Compliance Statement  
This Class B digital apparatus complies with Canadian ICES-003.  
Cet appareil numérique de la classe B est conforme à la norme NMB-003 du Canada.  
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FCC Compliance Statement  
This device complies with Part 15 rules. Operation is subject to the following two conditions:  
1. This device may not cause harmful interference, and  
2. This device must accept any interference received, including interference that may cause  
undesired operation.  
This equipment has been tested and found to comply with the limits for Class B Digital  
Devices, 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 residential  
environment. This equipment generates, uses, and can radiate radio frequency energy and, if  
not installed and used in accordance with the product manuals, may cause harmful interference  
to radio communications. However, there is no guarantee that interference will not occur in a  
particular installation. If this equipment does cause harmful interference to radio or television  
reception, the user is encouraged to do one or more of the following measures:  
• Reorient or relocate the receiving antenna.  
• Increase the separation between the equipment and receiver.  
• Connect the equipment into an outlet on a circuit different from that to which the receiver  
is connected.  
• Consult the dealer or an experienced RF service technician for help.  
The user is cautioned that any changes or modifications not expressly approved by Zebra  
Technologies could void the user’s authority to operate the equipment. To ensure compliance,  
this printer must be used with fully shielded communication cables.  
Environmental Management  
Do not dispose of this product in unsorted municipal waste. This product is recyclable, and  
should be recycled according to your local standards.  
For more information, please see our website at:  
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Who Should Use This Document  
Who Should Use This Document  
This User Guide is intended for use by any person who needs to operate or to troubleshoot  
problems with the printer.  
How This Document Is Organized  
The User Guide is set up as follows:  
Section  
Description  
This section describes what you get in your  
shipping box and provides an overview of printer  
features. This section also has procedures that  
describe how to open and close the printer and  
report any problems.  
This section describes how to set up your printer  
for the first time and use the most common  
operating procedures for loading media.  
This section provides media and print handling,  
font and language support, and the set up of less  
common printer configurations.  
This section covers the common printer options  
and accessories with brief descriptions and how to  
get you started using or configuring your printer  
option or accessory.  
This section provides routine cleaning and  
maintenance procedures.  
This section provides information about printer  
error reporting that you might need for printer  
troubleshooting. Assorted diagnostic tests are  
included.  
This section provides additional interface  
information and wiring diagrams to assist with  
printer to host system integration (typically a PC).  
This section provides external printer dimensions  
for the standard printer and printer with options.  
This section briefly covers printer configuration  
and includes a cross-reference to ZPL printer  
configuration commands.  
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vii  
Contacts  
Contacts  
Technical Support via the Internet is available 24 hours per day, 365 days per year.  
Web Site: www.zebra.com  
E-mail Back Technical Library:  
E-mail address: [email protected]  
Subject line: Emaillist  
Self Service Knowledge Base: www.zebra.com/knowledgebase  
Online Case Registration: www.zebra.com/techrequest  
Which Department  
Do You Need?  
Europe, Middle East,  
and Africa  
Asia Pacific  
and India  
The Americas  
Regional Headquarters Zebra Technologies Corporation  
475 Half Day Road, Suite 500  
Zebra Technologies Europe  
Limited  
Zebra Technologies Asia Pacific  
Pte. Ltd.  
Lincolnshire, IL 60069 USA  
Dukes Meadow  
Millboard Road  
Bourne End  
Buckinghamshire, SL8 5XF  
United Kingdom  
120 Robinson Road  
#06-01 Parakou Building  
Singapore 068913  
T: +1 847 634 6700  
Toll-free +1 866 230 9494  
F: +1 847 913 8766  
T: + 65 6858 0722  
F: +65 6885 0838  
T: +44 (0) 1628 556000  
F: +44 (0) 1628 556001  
Technical Support  
T: +1 877 ASK ZEBRA (275 9327) T: +44 (0) 1628 556039  
T: +65 6858 0722  
F: +65 6885 0838  
F: +1 847 913 2578  
F: +44 (0) 1628 556003  
For questions on the  
operation of Zebra  
equipment and software,  
please call your distributor.  
For additional assistance,  
contact us.  
All other areas:  
Kiosk printers:  
T: +1 866 322 5202  
Please have your model and  
serial numbers available.  
Repair Service  
Department  
T: +1 877 ASK ZEBRA (275 9327) T: +44 (0) 1772 693069  
T: +65 6858 0722  
F: +65 6885 0838  
F: +1 847 821 1797  
F: +44 (0) 1772 693046  
For back-to-base service  
and repair.  
Status updates:  
All other areas:  
To request a repair in the U.S.,  
Technical Training  
Department  
T: +1 847 793 6868  
T: +1 847 793 6864  
F: +1 847 913 2578  
T: +44 (0) 1628 556000  
F: +44 (0) 1628 556001  
T: + 65 6858 0722  
F: +65 6885 0838  
All other areas:  
For Zebra product training  
courses.  
Inquiry Department  
T: +1 877 ASK ZEBRA (275 9327) T: +44 (0) 1628 556037  
E: China:  
F: +44 (0) 1628 556005  
All other areas:  
om  
For product literature and  
distributor and dealer  
information.  
Customer Service  
Department (US)  
T: +1 877 ASK ZEBRA (275 9327) T: +44 (0) 1628 556032  
T: +65 6858 0722  
F: +65 6885 0836  
F: +44 (0) 1628 556001  
All other areas:  
Internal Sales  
Department (UK)  
For printers, parts, media,  
and ribbon, please call your  
distributor or contact us.  
Key:  
T: Telephone  
F: Facsimile  
E: E-mail  
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viii  
Document Conventions  
Document Conventions  
The following conventions are used throughout this document to convey certain information.  
Alternate Color (online only) Cross-references contain hot links to other sections in this  
guide. If you are viewing this guide online in .pdf format, you can click the cross-reference  
(blue text) to jump directly to its location.  
Command Line Examples Command line examples appear in CourierNew font. For  
example, type ZToolsto get to the Post-Install scripts in the bindirectory.  
Files and Directories File names and directories appear in Courier Newfont. For  
example, the Zebra<version number>.tarfile and the /root directory.  
Icons Used  
Caution • Warns you of the potential for electrostatic discharge.  
Caution • Warns you of a potential electric shock situation.  
Caution • Warns you of a situation where excessive heat could cause a burn.  
Caution • Advises you that failure to take or avoid a specific action could result in physical  
harm to you.  
Caution • (No icon) Advises you that failure to take or avoid a specific action could result in  
physical harm to the hardware.  
Important • Advises you of information that is essential to complete a task.  
Note • Indicates neutral or positive information that emphasizes or supplements important  
points of the main text.  
Example • Provides an example, often a scenario, to better clarify a section of text.  
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Contents  
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2
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3
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Notes • ___________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
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2
GC420t™ Thermal Printers  
GC420t™ Thermal Printers  
®
The Zebra GC420t™ model is the best value in a desktop thermal printer. The GC420t™  
printer provides thermal transfer and direct thermal printing at speeds up to 4 ips (inches per  
second) at a 203 dpi (dots per inch) print density. The GC420t™ supports both ZPL™ and  
EPL™ Zebra printer programming languages and a wide variety of interface and feature  
options.  
The GC420 printer features:  
Automatic printer language detection and switching between ZPL and EPL  
programming and label formats.  
Color-coded operator controls and media guides.  
Zebra™ Global Printing Solution – supports Microsoft Windows keyboard encoding  
(and ANSI), Unicode UTF-8 and UTF 16 (Unicode Transformation Formats), XML,  
ASCII (7 and 8 bit used by legacy programs and systems), basic single and double  
byte font encoding, Hexadecimal encoding, and custom character maps (DAT table  
creation, font linking, and character remapping).  
Improved printer performance: faster print speeds and a 32-bit processor.  
A complete suite of free software applications and drivers to configure printer  
settings, design and print labels and receipts, get printer status, import graphics and  
fonts, send programming commands, update firmware, and download files. Clone  
printer settings and send graphics, files, fonts, and firmware (updates) to one or more  
Zebra® Ethernet and locally connected printers with ZebraNet™ Bridge.  
Maintenance reporting enabled and customizable by the user.  
The GC420 printers offer these basic printer options:  
Label Dispense (Peel-Off).  
Zebra® ZBI 2.0™ (Zebra BASIC Interpreter) programming language. ZBI™ allows  
you to create custom printer operations that can automate processes, use peripherals  
(i.e. scanners, scales, keyboards, Zebra® KDU or KDU Plus™, etc.) all without being  
attached to a PC or network.  
This users guide provides all the information you need to operate your printer on a daily basis.  
To create label formats, refer to your programming guides or label design applications such as  
ZebraDesigner™.  
Your printer, when connected to a host computer, functions as a complete system for printing  
labels and tags.  
Note • Many printer settings may also be controlled by your printer’s driver or label design  
software. Refer to the driver or software documentation for more information.  
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3
What’s in the Box?  
What’s in the Box?  
Save the carton and all packing materials in case you need to ship or store the printer later.  
After unpacking, make sure you have all parts. Follow the procedures for inspecting the  
printer to familiarize yourself with printer parts so you can follow the instructions in this book.  
Documentation  
and Software  
Ribbon Core  
Printer  
Power Cord  
varies by locale or region  
Power  
Supply  
Unpack and Inspect the Printer  
When you receive the printer, immediately unpack it and inspect for shipping damage.  
Save all packing materials.  
Check all exterior surfaces for damage.  
Open the printer and inspect the media compartment for damage to components.  
If you discover shipping damage upon inspection:  
Immediately notify the shipping company and file a damage report. Zebra  
Technologies Corporation is not responsible for any damage to the printer incurred  
during shipment, and will not cover the repair of this damage under its warranty  
policy.  
Keep all packaging material for shipping company inspection.  
®
Notify your authorized Zebra reseller.  
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4
What’s in the Box?  
Your Printer  
Status  
Light  
Feed  
Button  
Release  
Latches  
Fan-FoldMedia  
Entry Slot  
Release  
Latches  
DC Power Switch  
and Receptacle  
Interface  
Connectors  
Opening the printer  
To access the media compartment, you must open the printer. Pull the release latches towards  
you and lift the cover. Check the media compartment for loose or damaged components.  
Caution • The discharge of electrostatic energy that accumulates on the surface of the  
human body or other surfaces can damage or destroy the printhead or electronic  
components used in this device. You must observe static-safe procedures when working  
with the printhead or the electronic components under the top cover.  
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5
What’s in the Box?  
Printer Features  
Printhead  
Ribbon Roll Holders  
Ribbon  
Take-Up  
Gear  
Supply  
Spindles  
Ribbon Motion  
Sensor  
Web (Gap)  
Sensor  
Take Up  
Spindles  
BlackLine  
Sensor  
Head-Up Sensor  
(inside)  
Fan-Fold  
Media Lock  
(screw)  
Media Guide  
Adjustment  
Roll  
Holders  
Dispenser Option  
Media Guides  
Peel Bar  
Platen  
Roller  
Sensor  
Dispenser Door  
(open)  
Pinch  
Roller  
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6
What’s in the Box?  
Operator Controls  
Power Switch  
Press up to turn ON or down to turn OFF the printer.  
Caution • The printer power should be turned off before connecting or disconnecting the  
communications and power cables.  
Power Switch  
Power ON  
Power OFF  
Power Switch  
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7
What’s in the Box?  
Feed Button  
• Tap the Feed button once to force the printer to feed one blank label.  
• Press the Feed button to take the printer out of a “pause” condition. The printer is put into  
“pause” by either a programming command or an error condition. See What the Status  
Light is Telling You on page 66 in the Troubleshooting chapter.  
• Use the Feed button for printer setup and status (see Feed Button Modes on page 76 in the  
Troubleshooting chapter).  
Status Light  
Located on the top case next to the feed button, the status light functions as a printer  
operational indicator (see Status Light Descriptions on page 66).  
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What’s in the Box?  
Closing the printer  
1. Hold the top cover and press the “kick-stand’ cover lock to release.  
Lower the top cover. The ribbon carriage automatically folds up into place.  
2. Press down until the cover snaps closed.  
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10  
Attaching Power  
Attaching Power  
Important • Set up your printer so that you can handle the power cord easily if needed. To  
make certain the printer cannot carry electrical current, you must separate the power cord  
from the power supply receptacle or AC electrical outlet.  
Caution • Never operate the printer and power supply in an area where they can get wet.  
Serious personal injury could result!  
1. Make sure the printer’s power switch is in the off position (down).  
2. Insert the AC power cord into the power supply.  
3. Plug the other end of the cord into an appropriate AC electrical outlet. Note: The active  
power light will go on if power is on at the AC outlet.  
4. Insert the power supply’s power connector into the printer’s power receptacle.  
Printer  
Plug Varies  
by Country  
AC  
Power  
Power  
Connector  
Cord  
Power  
Switch  
Power  
Supply  
Active Power  
Light  
Power  
Receptacle  
IEC 60320 C-5  
Note • Ensure the appropriate power cord with a three (3) prong plug and an IEC 60320-C5  
connector are used at all times. These power cords must bear the relevant certification mark of  
the country in which the product is being used.  
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11  
Loading Roll Media  
Loading Roll Media  
When you load media, you must place the roll onto the media hangers.  
You must use the correct media for the type of printing you require.  
Preparing Media  
Whether your roll media is inside or outside wound, you load it into the printer the same way.  
• Remove the outside length of media. During shipment, handling, or storage, the roll may  
become dirty or dusty. Removing the outside length of media avoids dragging adhesive or  
dirty media between the printhead and platen.  
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12  
Loading Roll Media  
Placing the Roll in the Media Compartment  
1. Open the printer. Remember that you need to pull the release latch levers toward the front  
of the printer.  
2. Open the media guides by turning the media guide adjustment knob towards the rear of the  
printer.  
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13  
Loading Roll Media  
3. Open the media roll holders. Pull the media guides open with your free hand and place the  
media roll on the roll holders and release the guides. Orient the media roll so that its  
printing surface will face up as it passes over the platen (drive) roller.  
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Loading Roll Media  
4. Pull the media so that it extends out of the front of the printer. Verify the roll turns freely.  
The roll must not sit in the bottom of the media compartment. Verify that the media’s  
printing surface is facing up.  
5. Push the media under both of the media guides. Close the media guides by turning the  
media guide adjustment knob to the front. The guides should just touch, but not restrict,  
the edges of the media.  
Under Media  
Guides  
6. Unless you need to load transfer ribbon, close the top cover. Remember that you need to  
release the cover lock, lower the top cover, and press down until the latches snap into  
place.  
7. If printer power is on, press the Feed Button to feed media. Otherwise, wait to turn on the  
printer and complete the printer ‘Getting Started’ instructions in this chapter.  
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Loading Transfer Ribbon  
Loading Transfer Ribbon  
Transfer ribbons come in several varieties and in some cases colors to match your application  
®
needs. Genuine Zebra transfer ribbons are specifically designed for your printer and Zebra  
®
brand media. Using non-Zebra media or ribbons not approved for use in your Zebra printer  
may damage your printer or printhead.  
• The media and ribbon types should be matched to provide you with optimal print results.  
• Always use ribbon that is wider than the media to protect the printhead from wear.  
• For direct thermal printing, do not load ribbon in the printer.  
®
Your printer needs to use Zebra Uni-Ribbon™ (universal ribbon). Uni-Ribbons have a ribbon  
®
out trailer (reflector) to stop printing when empty. Zebra Uni-Ribbon™ will work on older  
®
model Zebra desktop printers too.  
Uni-Ribbons are identified with a color coded leader.  
Blue - Performance Wax (5319)  
Silver - Premium Wax/Resin (3200)  
Gold - Performance Resin (5095) for synthetics (6 ips max. speed) and coated paper  
(4 ips max. speed)  
Red - Premium Resin (5100) for synthetics (4 ips max. speed)  
Before following these steps, prepare the ribbon by removing its wrapping and pulling its  
adhesive strip free.  
Notch  
Right Side  
(printer and roll)  
Adhesive Strip  
See Ribbon Overview on page 36 for more information on ribbon use.  
Important • DO NOT USE early model desktop printer ribbon cores! The older ribbon cores  
can be identified by notches on only one side of the ribbon core. These older cores are too large  
and will cause take-up spool to bind.  
Note • DO NOT USE ribbon cores with damaged notches - rounded, frayed, smashed, etc. The  
core notches should be square to lock the core on the spindle or the core may slip causing  
ribbon wrinkle, poor end of ribbon sensing or other intermittent failures.  
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16  
Loading Transfer Ribbon  
1. With the printer open, thread the ribbon through the ribbon carriage. Press the right side  
onto the spring loaded supply hub. Align the left side of the ribbon core notches to the left  
supply (spindle) hub spokes. Rotate the roll until the notches align and lock into the left  
side of the supply hub.  
2. Place an empty ribbon core on printer’s take-up spindles. Rotate the ribbon core until the  
notches align and lock into the left side of the take-up hub.  
You can find your first ribbon take-up core in the packing box. Subsequently, use the empty  
supply core to take up the next roll of ribbon.  
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17  
Loading Transfer Ribbon  
3. Attach the ribbon to the take up core. Use the adhesive strip on new rolls; otherwise, use  
tape. You must align the ribbon when you are attaching it to the core, so that it will be  
taken straight onto the core and align with the supply.  
4. Turn the ribbon take-up gear counter-clockwise (top moves toward rear) to remove slack  
from the ribbon.  
5. Verify that the media is loaded and ready to print and then close the printer cover.  
Remember that you need to release the cover lock, lower the top cover, and press down  
until the latches snap into place.  
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18  
Loading Transfer Ribbon  
6. If printer power is on, press the Feed button to have the printer feed a minimum of 10 cm  
(4 inches) of media to remove slack and ribbon wrinkle, and to align the ribbon on the  
spindles. Otherwise, wait to turn on the printer and complete the printer ‘Getting Started’  
instructions in this chapter.  
7. Change the print mode setting from direct thermal printing to thermal transfer to set the  
printer’s temperature profiles for thermal transfer media. This can be done with the printer  
driver, application software, or printer programming commands.  
When controlling printer operations with ZPL programming, refer to the Media Type  
(^MT) ZPL II command (follow the instructions in the ZPL Programming Guide).  
When controlling printer operations with EPL Page Mode, refer to the Options (O)  
EPL command (follow the instructions in the EPL Page Mode Programmers Guide).  
8. To verify the mode change from direct thermal printing to thermal transfer printing, use  
the Printing a Test (Printer Configuration) Label on page 19 to print a configuration label.  
The ‘PRINT METHOD’ should read ‘THERMAL-TRANS’ on the printer configuration  
status label.  
Your printer is now ready to print.  
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Printing a Test (Printer Configuration) Label  
Printing a Test (Printer Configuration) Label  
Before you connect the printer to your computer, make sure that the printer is in proper  
working order.  
You can do this by printing a configuration status label.  
1. Make sure the media is properly loaded and the top cover of the printer is closed. Then,  
turn the printer power on if you have not already done so. If the printer initializes with the  
status light blinking green (pause mode), press the Feed button once to set the printer in  
Ready (to print) mode. See the Troubleshooting on page 65 if the printer’s status light  
does not turn solid green (Ready).  
2. Press the Feed button two to three times to allow the printer to calibrate the printer for the  
installed media. The printer may feed several labels during this process.  
3. When the status light is solid green, press and hold the Feed button until the status light  
flashes once.  
4. Release the Feed button. A configuration label will print.  
If you cannot get this label to print, refer to Getting Started on page 9.  
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Pre-install Windows® Printer Drivers  
Pre-install Windows® Printer Drivers  
Zebra is changing the way you install and use your printer with your Windows based PC  
systems. We recommend that at minimum, the ZebraDesigner™ Windows® driver be pre-  
installed to take advantage of the advancements in ease of use and simplicity of the Windows  
operating systems since the release of Windows XP® SP2.  
Zebra provides the Zebra Setup Utilities (ZSU); a suite of Zebra® printer drivers, utilities, and  
communications and installation tools for use with most Windows PC operating systems.  
Zebra Web site (www.zebra.com) for latest versions.  
ZebraDesigner™ Driver and Zebra Setup Utilities (includes the driver): Supports  
Windows 7®, Windows Vista®, Windows XP®, Windows® 2000®, Windows Server® 2008,  
and Windows Server® 2003 operating systems. The driver supports 32 bit and 64 bit Windows  
operating systems and is Microsoft Certified. Zebra Setup Utilities and the ZebraDesigner  
driver support the following printer communication interfaces: USB, parallel, serial, Wired  
and Wireless Ethernet and Bluetooth (using a Bluetooth virtual printer port).  
Install the Zebra Setup Utilities before applying power to the printer connected to the PC  
(running a Zebra driver supported Windows operating system). The Zebra Setup Utility will  
prompt you to apply the printer power. Continue to follow the instructions to complete your  
printer installation.  
Plug’N’Play (PnP) Printer Detection and Windows® operating systems  
More recent Windows operating systems automatically detect the printer when it is connected  
via the USB interface. Depending on the hardware configuration and the Windows version,  
your printer may be Plug-and-Play (PnP) detected when connecting to the USB, parallel, or  
serial port interfaces. The printer drivers do not support serial port PnP installation at this  
time.The printer’s PC interface configuration for the parallel port must support and have  
bidirectional communications for PnP operations.  
The operating system automatically starts a “Add new hardware’ wizard when connecting the  
printer for the first time to the PC. If you have pre-loaded the driver suite with the Zebra Setup  
Utility, then the printer driver will automatically install. Go to your Windows printer directory  
and right-click and select ‘Properties’. Click on the ‘Print test page’ button to verify a  
successful installation.  
The Windows operating system will detect and re-link a previously installed printer if it is  
reconnected to the USB interface or if printer power is turned on after the PC has finished its  
restart of the operating system. Ignore the new device detected warnings and close the Task bar  
prompts. Wait several seconds for the operating system to match the printer to the driver  
software. The warnings will quit and the printer now should be ready to begin printing.  
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Pre-install Windows® Printer Drivers  
Universal Serial Bus (USB) Device Communications  
The printer is a terminal device (not a host or hub) when using a USB interface. You can refer  
to the USB Specification for details regarding this interface.  
Scanners, scales or other data input (terminal) devices must use the serial port (not the USB  
port) to send data to the printer.  
Serial Port and Windows® operating systems  
The Windows operating system default settings for the serial port communication closely  
match the printer’s defaults settings with one exception; the data Flow Control settings. The  
Windows default data Flow Control setting is NONE. The printer requires data Flow Control  
set to Hardware.  
®
Note • The printer does not support Windows Serial Port Plug and Play (PnP) device  
detection at this time.  
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Connecting your Printer to a Computer  
Connecting your Printer to a Computer  
®
The Zebra GC420 printers support a variety of interface options and configurations. These  
include: Universal Serial Bus (USB) interface, RS232 Serial, and Parallel (IEEE 1284.4).  
USB, Serial and Parallel  
The Zebra Setup Utility is designed to assist you with installing these interfaces. The  
cabling and unique parameters for each of these physical printer communication interfaces is  
discussed in the following pages to assist you with making configuration setup choices prior to  
and immediately following applying power. The Zebra Setup Utilities configuration wizards  
will instruct you to turn the printer’s power on at the appropriate time to complete the  
installation of your printer.  
Caution • Keep the power switch in the OFF position when attaching the interface cable.  
The power cord must be inserted into the power supply and the power receptacle on the  
back of the printer before connecting or disconnecting the communications cables.  
Interface Cable Requirements  
Data cables must be of fully shielded construction and fitted with metal or metallized  
connector shells. Shielded cables and connectors are required to prevent radiation and  
reception of electrical noise.  
To minimize electrical noise pickup in the cable:  
Keep data cables as short as possible (6 foot [1.83 m] recommended).  
Do not tightly bundle the data cables with power cords.  
Do not tie the data cables to power wire conduits.  
.
Important • This printer complies with FCC “Rules and Regulations,” Part 15, for Class B  
Equipment, using fully shielded data cables. Use of un-shielded cables may increase radiated  
emissions above the Class B limits.  
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Connecting your Printer to a Computer  
USB Interface Requirements  
Universal Serial Bus (version 2.0 compliant) provides a fast interface that is compatible with  
your existing PC hardware. USB’s “plug and play” design makes installation easy. Multiple  
printers can share a single USB port/hub.  
When using a USB cable (not supplied with your printer), verify that the cable or cable  
packaging bears the “Certified USB™” mark (see below) to guarantee USB 2.0 compliance.  
USB Cable  
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Connecting your Printer to a Computer  
Serial Communications  
The printer has a DCE serial communication port for hardware compatibility with legacy 888  
printers. The required cable must have a nine-pin “D” type (DB-9P) male connector on one  
end which plugs into the mating (DB-9S) serial port located on the back of the printer. The  
other end of this signal interface cable connects to a serial port on the host computer. The cable  
is a Null-Modem (cross-over signal connections) cable. For pinout information, refer to  
Appendix A.  
The serial port communication settings between the printer and host (typically a PC) must  
match for reliable communication. The Bits per second (or Baud rate) and Flow control are the  
most common settings that get changed. The host (typically a Windows PC) needs to have the  
data Flow control changed to match the printer’s default communication method: Hardware  
and is noted by the Host Handshake setting DTR/Xon/Xoff. This combined hardware  
(DTR) and software (Xon/Xoff) mode may need to change depending upon use with non-  
Zebra application software or the serial cable variation in use.  
Serial communications between the printer and the host computer can be set by:  
Autobaud synchronization  
ZPL programming ^SCcommand  
EPL programming Ycommand  
Resetting the printer to its default printer configuration.  
Autobaud  
Autobaud synchronization allows the printer to automatically match the communication  
parameters of the host computer. To autobaud:  
1. Press and hold the feed button until the green status LED flashes once, twice, and then  
three times.  
2. While the status LED flashes, send the ^XA^XZcommand sequence to the printer.  
3. When the printer and host are synchronized, the LED changes to solid green. (No labels  
will print during autobaud synchronization.)  
ZPL ^SC Command  
Use the Set Communications (^SC) command to change the communications settings on the  
printer.  
1. With the host computer set at the same communications settings as the printer, send the  
^SCcommand to change the printer to the desired settings.  
2. Change the host computer settings to match the new printer settings.  
Refer to the ZPL Programming Guide for more information about this command.  
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Connecting your Printer to a Computer  
EPL Y Command  
Use the serial port setup (Y) command to change the communications settings on the printer.  
1. With the host computer set at the same communications settings as the printer, send the  
Ycommand to change the printer to the desired settings. Note: the Y command does not  
support setting the data flow control, use the Xon/Xoffsetting.  
2. Change the host computer settings to match the new printer settings.  
Refer to the EPL Page Mode Programming Guide for more information about this command.  
Resetting the Default Serial Port Parameters  
Do the following to reset the communications parameters on the printer to the factory defaults  
(serial communication settings are: 9600baud, 8bit word length, NOparity, 1stop bit, and  
DTR/XON/XOFFdata flow control).  
1. Press and hold the feed button until the green status LED flashes once, waits a moment  
and flashes twice, and then waits again before flashing three times (release  
immediately).  
2. While the status LED rapidly flashes amber and green, press the feed button. Serial  
communications between the printer and the host computer can be set by the ZPL ^SC  
command or the EPL Ycommand.  
Note • Early models of Zebra® printers running the EPL programming language had 9600  
baud, NOparity, 8data bits, 1stop bit and a HARDWAREand SOFTWARE(merged) data  
control (essentially DTR/Xon/Xoff) as the default serial port settings. The Windows operating  
system flow control setting was Hardware for most applications.  
Serial Cable  
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Connecting your Printer to a Computer  
Parallel Port  
The required cable must have a 25 pin “D” type (DB-25P) male connector (host) on one end  
and a Centronics (printer) on the other end (IEEE 1284 A-B parallel interface specification).  
Parallel Cable  
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After Your Printer is Connected  
After Your Printer is Connected  
Now that you have basic communication to your printer, you may want to test printer  
communications and then install other printer related applications, drivers or utilities.  
Testing Communications by Printing  
Verifying the print system’s operation is a relatively simple process. For Windows operating  
systems, the Zebra Setup Utility or the Windows ‘Printers and Faxes’ Control Panel to access  
and print a test label. For non-Windows operation systems, copying a basic ASCII text file  
with a single command (~WC) to print a configuration status label.  
Test Printing with Zebra Setup Utility:  
1. Open the Zebra Setup Utility.  
2. Click on the newly installed printer’s icon to select the printer and activate the printer  
configuration buttons below it in the window.  
3. Click the ‘Open Printer Tools’ button.  
4. In the ‘Print’ tab window, click on the ‘Print configuration label’ line and click on the  
‘Send’ button. The printer should print a configuration status label.  
Test Printing with Windows ‘Printer and Faxes’ menu:  
1. Click on the Windows ‘Start’ menu button, to access the ‘Printers and Faxes’ menu or  
‘Control Panel’ to access the ‘Printers and Faxes’ menu. Open the menu.  
2. Select the newly installed printer’s icon to select the printer and right-click the mouse to  
access the printer ‘Properties’ menu.  
3. From the printer’s ‘General’ tab window, click on the ‘Print Test Page’ button. The printer  
should print a Windows test print page.  
Test Print with a Copied ZPL Command File for Non-Windows Operating Systems:  
1. Create a text file with the following ASCII three characters: ~WC  
2. Save the file as: TEST.ZPL (an arbitrary file name and extension name).  
3. Copy the file to the printer. For DOS, a file sent to a printer connected to the system’s  
parallel port would be as simple as:  
COPY TEST.ZPL LPT1  
Other interface connection types and operating systems will have different command  
strings. See your operating system documentation for detailed instructions to copy to the  
appropriate printer interface for this test.  
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After Your Printer is Connected  
Notes • ___________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
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Print Operations  
This section provides media and print handling, font and language support, and the setup of  
less common printer configurations.  
Contents  
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Determining Printer Configuration  
Determining Printer Configuration  
The printer uses a ZPL printer configuration status label to report the printer’s configuration  
status for both EPL and ZPL operations.The ZPL style label provides a more intuitive and  
functionally descriptive naming conventions than the EPL style printer status label.  
Operational status (darkness, speed, media type, etc.), installed printer options (network,  
interface settings, cutter, etc.) and printer description information (serial number, model name,  
firmware version, etc.) are all includes on the status label. See Printing a Test (Printer  
on page 87 for detail on printer configuration and the ZPL commands that control the printer  
settings listed on the Printer Configuration Status Label.  
To get an EPL style printer configuration status label, send the printer the EPL Ucommand.  
See the EPL programmer’s guide for more information on the various EPL Ucommands and  
interpreting the settings displayed on these labels.  
Long Term Printer In-activity or Storage  
Overtime the printhead may stick to the platen (drive) roller. To prevent this, always store the  
printer with a piece of media (a label or paper) between the printhead and platen roller. Do not  
ship the printer with a roll of media installed or damage to the printer or media may result.  
Thermal Printing  
Caution • The printhead becomes hot while printing. To protect from damaging the  
printhead and risk of personal injury, avoid touching the printhead. Only use the cleaning  
pen to perform printhead maintenance.  
Caution • The discharge of electrostatic energy that accumulates on the surface of the  
human body or other surfaces can damage or destroy the printhead or electronic  
components used in this device. You must observe static-safe procedures when working  
with the printhead or the electronic components under the top cover.  
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Modes of Printing  
Modes of Printing  
You can operate this printer in many different modes and media configurations:  
• Direct thermal printing (which uses heat sensitive media to print).  
• Thermal transfer printing (which uses ribbon to heat transfer print to the media).  
• Standard Tear-Off mode allows you to tear off each label (or batch print a strip of labels)  
after it is printed.  
• Label Dispense Mode: If an optional dispenser is installed, the backing material can be  
peeled away from the label as it is printed. After this label is removed, the next one is  
printed.  
• Stand-alone: The printer can print without being connected to a computer using the  
printer’s auto running label form feature (programming based) or by using a data input  
device connected to the printer’s serial port. This mode accommodates data input devices,  
®
®
such as scanners, weigh scales, Zebra KDU Plus™ or Zebra KDU (Keyboard Display  
Unit), etc.  
Print Media Types  
Important • Zebra strongly recommends the use of Zebra-brand supplies for continuous  
high-quality printing. A wide range of paper, polypropylene, polyester, and vinyl stock has  
been specifically engineered to enhance the printing capabilities of the printer and to prevent  
premature printhead wear. To purchase supplies, go to http://www.zebra.com/howtobuy.  
Your printer can use various types of media:  
Standard media—Most standard (non-continuous) media uses an adhesive backing that  
sticks individual labels or a continuous length of labels to a liner.  
Continuous roll media—Most continuous roll media is direct thermal media (similar to  
FAX paper) and is used for receipt or ticket style printing.  
Linerless media—Linerless labels have an adhesive backing, but they are wound onto a  
core without a liner. The media typically is perforated and may have black marks on the  
bottom surface of the media to indicate label separations. The top surface of linerless  
media labels have a special coating that keeps the labels from sticking to each other. The  
printer must be equipped with a special Linerless option to be able to use linerless media  
to keep the media from sticking to the printer.  
Tag stock—Tags are usually made from a heavy paper (up to 0.0075in./0.19mm thick).  
Tag stock does not have adhesive or a liner, and it is typically perforated between tags.  
For more information on basic media types, see Table 1.  
The printer typically uses roll media, but you can use fan-fold or other continuous media too.  
Use the correct media for the type of printing you require. You must use direct thermal  
media.When printing without a ribbon, you must use direct thermal media. When using  
ribbon, you must use thermal transfer media.  
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Print Media Types  
Table 1 • Types of Media Roll and Fanfold Media  
Media Type  
How It Looks  
Description  
Non-Continuous  
Roll Media  
Roll media is wound on a core that can be 0.5 to 1.5 in. (12.7 to  
38.1 mm) in diameter. Labels have adhesive backing that sticks  
them to a liner, and they are separated by gaps, holes, notches, or  
black marks. Tags are separated by perforations. Individual labels  
are separated by one or more of the following methods:  
Web media separates labels by gaps, holes, or notches.  
Black mark media uses pre-printed black marks on the back  
side of the media to indicate label separations.  
Perforated media has perforations that allow the labels or tags  
to be separated from each other easily. The media may also  
have black marks or other separations between labels or tags.  
Non-Continuous  
Fanfold Media  
Fan-Fold media is folded in a zigzag pattern. Fanfold media can  
have the same label separations as non-continuous roll media.  
The separations would fall on or near the folds.  
Continuous  
Roll Media  
Roll media is wound on a core that can be 0.5 to 1.5 in. (12.7 to  
38.1 mm) in diameter. Continuous roll media does not have gaps,  
holes, notches, or black marks to indicate label separations. This  
allows the image to be printed anywhere on the label. A cutter  
can be used to cut apart individual labels. With continuous media,  
use the transmissive (gap) sensor so the printer can detect when  
the media runs out.  
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Replacing Supplies  
Determining Thermal Media Types  
Thermal transfer media requires ribbon for printing while direct thermal media does not.  
To determine if ribbon must be used with a particular media, perform a media scratch test.  
To perform a media scratch test, complete these steps:  
1. Scratch the print surface of the media with a finger nail or pen cap. Press firmly and  
quickly while dragging it across the media surface. Direct thermal media is chemically  
treated to print (expose) when heat is applied. This test method uses friction heat to expose  
the media.  
2. Did a black mark appear on the media?  
If a black mark...  
Then the media is...  
Does not appear on the media  
Appears on the media  
Thermal transfer. A ribbon is required.  
Direct thermal. No ribbon is required.  
Replacing Supplies  
If labels or ribbon run out while printing, leave the printer power on while reloading (data loss  
results if you turn off the printer). After you load a new label or ribbon roll, press the Feed  
button to restart.  
Always use high quality, approved labels, tags and ribbons. If adhesive backed labels are used  
that don’t lay flat on the backing liner, the exposed edges may stick to the label guides and  
rollers inside the printer, causing the label to peel off from the liner and jam the printer.  
Permanent damage to the printhead may result if a non-approved ribbon is used as it may be  
wound incorrectly for the printer or contain chemicals corrosive to the printhead.  
Adding a New Transfer Ribbon  
If ribbon runs out in the middle of a print job, the indicator lights red and the printer waits for  
you to add a fresh roll.  
1. Keep the power on as you change ribbon.  
2. Open the top cover, then cut the used ribbon so you can remove the cores.  
3. Load a new ribbon roll and empty ribbon core. If necessary, review the Ribbon Loading  
steps. Note: Do Not Use ribbon cores with damaged notch. The notches should have  
square corners.  
4. Close the top cover.  
5. Press the Feed button to restart printing.  
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Adjusting the Print Width  
Replacing a Partially Used Transfer Ribbon  
To remove used transfer ribbon, perform the following steps.  
1. Cut the ribbon from the take-up roll.  
2. Remove the take-up roll and discard used ribbon.  
3. Remove the supply roll and tape the end of any fresh ribbon to prevent it from  
unwrapping. When reinstalling a partially used supply roll, tape the cut end onto the  
empty take-up roll.  
Adjusting the Print Width  
Print width must be set when:  
You are using the printer for the first time.  
• There is a change in media width.  
Print width may be set by:  
• The Windows printer driver or application software such as ZebraDesigner™.  
• The five-flash sequence in Feed Button Modes on page 76.  
• Controlling printer operations with ZPL programming; refer to the Print Width (^PW)  
command (consult your ZPL Programming Guide).  
• Controlling printer operations with EPL Page Mode programming, refer to the Set Label  
Width (q) command (consult your EPL Programmers Guide).  
Adjusting the Print Quality  
Print quality is influenced by the heat (density) setting of the printhead, the print speed, and the  
media in use. Experiment with these settings to find the optimal mix for your application. Print  
quality can be set with the Zebra Setup Utility’s ‘Configure Print Quality’ routine.  
Note • Media manufactures may have specific recommendations for speed settings for your  
printer and the media. Some media types have lower maximum speeds than your printer’s  
maximum speed.  
The relative darkness (or density) setting can be controlled by:  
• The six-flash sequence in Feed Button Modes on page 76. This will overwrite any ZPL  
and EPL programmed darkness/density settings.  
• The Set Darkness (~SD) ZPL command (consult your ZPL Programming Guide).  
• The Density (D) EPL command (consult your EPL Programmers Guide).  
If you find that the print speed needs to be adjusted, use:  
• The Windows printer driver or application software such as ZebraDesigner™.  
• The Print Rate (^PR) command (consult your ZPL Programming Guide).  
• The Speed Select (S) command (consult your EPL Programmers Guide).  
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Media Sensing  
Media Sensing  
The printer has automatic media sensing capability. The printer is designed to continuously  
check and adjust media length sensing for minor variations. Once the printer is printing or  
feeding media, the printer continually checks and adjusts the media sensing to accommodate  
for minor changes in media parameters from label to label on a roll and from roll to roll of  
media. The printer will automatically initiate a media length calibration if the expected media  
length or the label to label gap distance has exceeded the acceptable variation range when  
starting a print job or feeding media. The automatic media sensing in the printer works the  
same for printer operations that use EPL and ZPL label formats and programming.  
If the printer does not detect labels or black marks (or notches with blackline sensing) after  
feeding the media the default maximum label length distance of 39 inches (1 meter), then the  
printer will switch to continuous (receipt) media mode. The printer will keep these settings  
until changed by software, programming or a manual calibration with different media.  
Optionally, the printer can be set to do a short media calibration after printer power up or when  
closing the printer with power on. The printer will then feed several labels while calibrating.  
The printer’s media settings can be verified by printing a Printer Configuration label. See the  
The maximum distance that the automatic media type detection and sensing will check can be  
reduced by using the ZPL Maximum Label Length command (^ML). It is recommended that  
this distance be set to no less than two times the longest label being printed. If the largest label  
being printed was a 4 by 6 inch label, then the maximum label (media) length detection  
distance can be reduced from the default distance of 39 inches down to 12 inches.  
If the printer has difficulty automatically detecting the media type and auto-calibrating, see  
Manual Calibration on page 72 to perform an extensive calibration. It includes a printed graph  
of sensor operation for your media. This method disables the printer’s automatic media  
sensing capability until the printer’s default parameters are reset to the factory defaults with  
the four flash Feed button mode. See the Feed Button Modes on page 76 for more details.  
The automatic media calibration can be modified, turned on or turned off to meet your needs.  
Sometimes print job conditions require that the printer use all the media on a roll. The two  
automatic media conditions, power up with media loaded and closing the printer with power  
on, can be controlled individually with the ZPL Media Feed command, ^MF. The feed action  
discussed in the ZPL programmers guide for the ^MFcommand is primarily for automatic  
media sensing and calibration. The automatic media calibration that controls the dynamic  
media (label to label) calibration is the ^XScommand. If multiple media types of different  
lengths, material or detection methods (web/gap, black mark, notches or continuous) are used,  
you should not change these settings.  
The media calibration and detection process can also be refined to match the media type  
loaded into the printer. Use the ZPL Media Tracking command (^MN) to set the media type.  
Sometimes the printer can detect preprinted media as the gap between labels or the liner  
backing with print as a black marks. If the ^MNparameter for continuous media is set, then the  
print does not preform the automatic calibration. The ^MNcommand also includes an  
automatic calibration parameter (^MNA) to return the printer to its default setting to  
automatically detect all media types.  
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Ribbon Overview  
Ribbon Overview  
Ribbon is a thin film that is coated on one side with wax, resin, or wax resin, which is  
transferred to the media during the thermal transfer process. The media determines whether  
you need to use ribbon and how wide the ribbon must be. When ribbon is used, it must be as  
wide as or wider than the media being used. If the ribbon is narrower than the media, areas of  
the printhead are unprotected and subject to premature wear.  
When to Use Ribbon  
Thermal transfer media requires ribbon for printing while direct thermal media does not.  
Direct thermal media should never be used with ribbon. Bar codes and graphics can get  
distorted. To determine if ribbon must be used with a particular media, perform a media  
scratch test.  
Coated Side of Ribbon  
Ribbon can be wound with the coated side on the inside or outside. This printer can only use  
ribbon that is coated on the outside. If you are unsure which side of a particular roll of ribbon  
is coated, perform an adhesive test or a ribbon scratch test to determine which side is coated.  
Outside  
Inside  
To determine which side of a ribbon is coated, complete these steps:  
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Ribbon Overview  
Ribbon Test with Adhesive  
If you have labels available, perform the adhesive test to determine which side of a ribbon is  
coated. This method works well for ribbon that is already installed.  
To perform an adhesive test, complete these steps:  
1. Peel a label from its liner.  
2. Press a corner of the sticky side of the label to the outer surface of the roll of ribbon.  
3. Peel the label off of the ribbon.  
4. Observe the results. Did flakes or particles of ink from the ribbon adhere to the label?  
If ink from the ribbon...  
Then...  
Adhered to the label  
The ribbon is coated on the outside and can be used with  
the GC420 printer.  
Did not adhere to the label  
The ribbon is coated on the inside and can not be used in  
the GC420 printer.  
Ribbon Scratch Test  
Perform the ribbon scratch test when labels are unavailable.  
To perform a ribbon scratch test, complete these steps:  
1. Unroll a short length of ribbon.  
2. Place the unrolled section of ribbon on a piece of paper with the outer surface of the  
ribbon in contact with the paper.  
3. Scratch the inner surface of the unrolled ribbon with your fingernail.  
4. Lift the ribbon from the paper.  
5. Observe the results. Did the ribbon leave a mark on the paper?  
If the ribbon...  
Then...  
Left a mark on the paper  
The ribbon is coated on the outside and can be used with  
the GC420 printer.  
Did not leave a mark on the The ribbon is coated on the inside and can not be used in  
paper the GC420 printer.  
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Printing on Fan-Fold Media  
Printing on Fan-Fold Media  
Printing on fan-fold media requires you to adjust the media guide’s stop position.  
1. Open the top cover.  
Fan-Fold  
Media Path  
2. With a sample of your media, adjust the media roll holders to the width of the media. The  
hangers should just touch, but not restrict, the edges of the media.Tighten the screw using  
a small Phillips driver #1.  
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Printing on Fan-Fold Media  
3. With a sample of your media, adjust the guides to the width of the media.The guides  
should just touch, but not restrict, the edges of the media.  
4. Run the media between the media guide and roll holders.  
5. Close the top cover.  
After printing or feeding several labels: If the media does not track down the center (moves  
from side to side) or the sides of the media (liner, tag, paper, etc.) are frayed or damaged when  
exiting the printer, then the media guides or roll holders may need further adjustment.  
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Printing with Externally Mounted Roll Media  
Printing with Externally Mounted Roll Media  
The GC420 printer accommodates externally mounted roll media similar to the printer’s  
support of fan-fold media. The printer requires the media roll and stand combination to have a  
low initial inertia to pull the media off the roll.  
Zebra at this time does not offer an external media option for the GC420 printer.  
Externally Mounted Roll Media Considerations:  
• The media ideally should enter the printer directly behind the printer through the fan-fold  
media slot in the rear of the printer. See Printing on Fan-Fold Media on page 38 for media  
loading.  
• Lower the print speed to decrease the chance of motor stalls. The roll typically has the  
highest inertia when trying to start the roll moving. Larger media roll diameters require the  
printer to have more torque applied to get the roll moving.  
• The media should move smoothly and freely. The media should not slip, skip, jerk, bind  
and then move, etc. when mounted on your media stand.  
• The printer should not touch the media roll.  
• The printer should not slip or lift up off the operating surface.  
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Fonts and Your Printer  
Fonts and Your Printer  
The GC420 printer supports your language and font requirements with a variety of internal  
fonts, on-board font scaling, international font sets and character code page support, Unicode  
support, and font download.  
The GC420 printer’s font capabilities are programming language dependent. The EPL™  
programming language provides for basic bitmapped fonts and international code pages. The  
ZPL™ programming language provides advanced font mapping and scaling technology to  
support outline fonts (TrueType™ or OpenType™) and Unicode character mapping as well as  
basic bitmapped fonts and character code pages. ZPL and EPL programming guides describe  
and document the fonts, code pages, character access, listing fonts, and limitations for their  
respective printer programming languages. See the printer programming guides for  
information on Text, Fonts and Character support.  
The GC420 printer includes utilities and application software that support font download into  
the printer for both printer programming languages.  
Localizing the Printer with Code Pages  
The GC420 printer supports two sets of language, region and character sets for permanent  
fonts loaded into the printer for each printer programming language, ZPL and EPL. The printer  
supports localization with common international character map code pages.  
• For ZPL code page support, including Unicode, see the ^CIcommand in the ZPL  
programmer’s guide.  
• For EPL code page support, see the Icommand in the EPL programmer’s guide.  
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Fonts and Your Printer  
Identifying Fonts in Your Printer  
Fonts and memory are shared by the programming languages in the printer. Fonts can be  
loaded in many memory areas in the GC420 printer. ZPL programming can recognize EPL and  
ZPL fonts. EPL programming can only recognize EPL fonts. See the respective programmer  
guides for more information on fonts and printer memory.  
ZPL Fonts:  
• To manage and download fonts for ZPL print operation, use the Zebra Setup utility or  
ZebraNet™ Bridge.  
• To display all of the fonts loaded in your printer, send the printer the ZPL ^WD command.  
See the ZPL Programmers Guide for details.  
Bitmap fonts in the various printer memory areas are identified by the .FNT file  
extension in ZPL.  
Scalable fonts are identified with the .TTF, .TTE or .OTF file extensions in ZPL.  
EPL does not support these fonts.  
EPL Fonts:  
• To download fonts for EPL print operations, use the Zebra Setup Utility or ZebraNet™  
Bridge to send files to the printer.  
• To display Soft Fonts (ext.) available to EPL, send the printer the EPL command EI.  
All EPL fonts displayed are bitmap fonts. They do not include the .FNT file extension  
or the horizontal (H) or vertical (V) designators that are displayed with the ZPL  
command ^WDas described above in ZPL Fonts.  
• To remove non Asian EPL fonts with EPL programming, use the EKcommand.  
• To remove EPL Asian fonts from the printer, use the ZPL ^IDcommand.  
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Stand Alone Printing  
Stand Alone Printing  
Your printer can be configured to work without being attached to a computer. The printer has  
the ability to automatically run a single label form. One or more downloaded label forms can  
®
be accessed and run with a terminal or wedge device or a Zebra KDU (keyboard display unit)  
to call a label form. These methods allow the developer to incorporate data input devices, such  
as scanners or weight scales, to the printer via the serial port.  
Label formats can be developed and stored in the printer to support labels that have:  
• No data entry required and print when the Feed button is pressed.  
• No data entry required and print when a label is removed from the printer’s optional label  
dispenser.  
• One or more data variables to be entered via the terminal or wedge device. The label will  
print after the last variable data field has been input.  
• One or more label formats that are called by scanning bar codes containing programming  
to run a label form.  
• Label forms designed to work as a process chain with each label including a bar code  
containing the programming to run the next label in the process sequence.  
Both printer programming languages support special label forms that will automatically run  
after a power cycle or reset. The ZPL looks for a file named AUTOEXEC.ZPL and EPL  
looks for a label form named AUTOFR. If both files are loaded in the GC420 printer, then  
only the AUTOEXEC.ZPL will run. The EPL AUTOFR form runs until it is disabled. Both  
files must be deleted from the printer followed by a reset or a power cycle to completely  
remove the files.  
Note • The GC420 EPL AUTOFRcommand can only be disabled with NULLcharacter (00 hex  
or ASCII 0). The printer will ignore the other character that normally disables the AUTOFFR  
form operation in most other EPL printers, the XOFF character (13 hex or ASCII 19).  
The printer can source up to 750mA through a 5 volt line shared between the parallel and serial  
ports. See Appendix A for more information on the printer’s serial port interface.  
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Sending Files to the Printer  
Sending Files to the Printer  
Graphics, fonts and programming files can be sent to the printer from the Microsoft Windows  
operating systems by using the Zebra Setup Utilities (and driver), ZebraNet™ Bridge or  
®
Zebra ZDownloader found on the user's CD or at www.zebra.com. These methods are  
common for both programming languages and the GC420 printers.  
Print Meter  
The GC420 printer has the capability to report printhead maintenance alerts. The printer can  
provide cleaning and early warning of end of calculated printhead life alerts. If the RTC (Real  
Time Clock) is installed in the printer, the printhead life and history reporting will also include  
the date. By default, print metering alerts are disabled.  
Many of the print meter messages and reports are customize able. See the ZPL or EPL  
Programming Guides for more information on the Print Meter.  
To active the Print Meter Alerts, send one of the following commands to the printer:  
EPL command oLY  
ZPL command ^JH,,,,,E  
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46  
Label Dispenser Option  
Label Dispenser Option  
The factory installed label dispenser option allows you to print a label with backing  
(liner/web) being removed from the label as it prints, ready for application. When printing  
multiple labels, removing the dispensed (peeled) label notifies the printer to print and dispense  
the next label.  
To use dispenser-mode correctly, use your printer driver to activate the label (taken) sensor  
along with these typical label settings which include but are not limited to length, non-  
continuous (gap), and web (liner). Otherwise, you must send the ZPL or EPL programming  
commands to the printer.  
When programming in ZPL, you can use the following command sequences shown below  
and refer to your ZPL Programming Guide for more information on ZPL programming.  
^XA ^MMP ^XZ  
^XA ^JUS ^XZ  
When programming in EPL, send the Options (O) command with the ‘P’ command  
parameter (OP) to enable the Label Taken sensor. Other printer option parameters may also be  
included with the Options command string. Refer to your EPL Programmers Guide for more  
information on programming with EPL and the Options (O) command behaviors.  
1. Load your labels into the printer. Close the printer and press the Feed button until a  
minimum of 4 inches or 100 millimeters of exposed labels exit the printer. Remove the  
exposed labels from the liner.  
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Label Dispenser Option  
2. Lift the liner over the top of the printer and open the dispenser door.  
3. Insert the label liner between the dispenser door and the printer body.  
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Label Dispenser Option  
4. Close the dispenser door.  
5. Press the Feed button to advance the media.  
6. During the print job, the printer will peel off the backing and present a single label. Take  
the label from the printer to allow the printer to print the next label. Note: If you did not  
activate the label taken sensor to detect the removal of the dispensed (peeled) label with  
software commands, the printer will stack and eject peeled labels.  
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Zebra® KDU — Printer Accessory  
®
Zebra KDU — Printer Accessory  
®
The Zebra KDU (keyboard display unit) is a small terminal unit that interfaces with the  
printer for accessing EPL label forms stored in the printer.  
The KDU is strictly a terminal and does not have the capability to store data or set up  
parameters. The KDU is used for the following functions:  
List label forms stored in printer  
Retrieve label forms stored in printer  
Input variable data  
Printing labels  
v
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KDU Plus™ — Printer Accessory  
KDU Plus™ — Printer Accessory  
The KDU Plus™ is a terminal device with memory for storing files and maintaining one or  
more remote printers. The KDU Plus has a larger laptop style keyboard than the Zebra’s  
original KDU design.  
The KDU Plus is designed for the following functions:  
List label forms stored in printer  
Retrieve label forms stored in printer  
Input variable data  
Printing labels  
File storage and transfer  
The KDU Plus is designed to work with ZPL and EPL printers by dynamically detecting and  
switching the printer’s communications configuration (DTE or DCE) to match your Zebra  
printer. By default, the KDU Plus will start up forms mode. This is compatible with the  
operation of Zebra’s original KDU. The KDU Plus is configurable to work in ZPL or terminal  
modes too.  
The KDU Plus has file transfer and storage capabilities. This is great for maintaining remote  
and stand alone printers with label forms, logos and smaller font sets.  
The KDU Plus has two configurable serial port and a PS/2 port to connect to other data input  
devices such as scanners, weigh scales, etc..  
The +5 volts from the printer’s serial (pin 9) provides power for the KDU Plus and any  
additional input devices attached to the KDU Plus.  
Maximum total current draw for the GC420 printer’s serial (and parallel) port: 750mA  
The KDU Plus’s current without external input devices attached is: 50mA  
25mA*  
120mA*  
Current Draw  
45mA*  
50mA  
* - Not real values  
( 45mA + 120mA + 25mA ) + 50mA  
<
Max. Current  
Caution • The KDU Plus’s input ports (AUX1, AUX2, and PS/2 style) are not fused.  
Exceeding the total current draw available could damage an input device, KDU Plus, or  
the printer.  
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ZBI 2.0™ — Zebra Basic Interpreter  
ZBI 2.0™ — Zebra Basic Interpreter  
Customize and enhance your printer with ZBI 2.0™ optional programming  
language. ZBI 2.0 allows Zebra printers to run applications and take input from  
scales, scanners and other peripherals—all without a PC or network connection.  
ZBI 2.0 works with the ZPL printer command language so that printers can  
understand non-ZPL data streams and convert them into labels. That means the  
Zebra printer can create bar codes and text from input received, non-ZPL label  
formats, sensors, keyboards and peripherals. Printers can also be programmed to  
interact with PC based database applications to retrieve information to be used on  
printed labels.  
the ZBI 2.0 store at www.zebrasoftware.com.  
the Zebra Web site: www.zebra.com.  
An intuitive ZBI-Developer™ programming utility is used to create, test and  
www.zebra.com.  
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ZBI 2.0™ — Zebra Basic Interpreter  
Notes • ___________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
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Maintenance  
Cleaning  
54  
Cleaning  
When you clean the printer, use one of the following supplies that best suits your needs:  
Order  
Cleaning Supplies  
Intended Purpose  
Quantity  
Set of 12  
Set of 25  
Cleaning pens (105950-035)  
Cleaning swabs (105909-057)  
Clean printhead  
Clean media path, guides and sensors  
You can obtain cleaning supplies at www.zipzebra.com.  
The cleaning process takes just a couple of minutes using the steps outlined below.  
Printer Part  
Method  
Let the printhead to cool for a minute, then use a When using ribbon:  
new cleaning pen to swab the dark line on the after every roll of  
printhead cleaning from the center to the outside ribbon; when using  
Interval  
Printhead  
edges of the printhead.  
direct thermal: after  
every roll of media.  
Platen roller  
Remove the platen roller to clean. Clean the  
roller thoroughly with 90% medical-grade  
alcohol and a cleaning swab or lint-free cloth.  
As needed.  
Peel bar  
Clean it thoroughly with 90% medical-grade  
alcohol and a fiber-free cleaning swab.  
Media path  
Let alcohol dissipate and the printer dry  
completely.  
Exterior  
Interior  
Water-dampened cloth.  
Gently brush out printer.  
Caution • Adhesives and media material can over time transfer onto the printer  
components along the media path including the platen and printhead. This build-up can  
accumulate dust and debris. Failure to clean the printhead, media path and platen roller  
could result in inadvertent loss of labels, label jams and possible damage to the printer.  
Important • Using too much alcohol can result in contamination of the electronic  
components requiring a much longer drying time before the printer will function properly.  
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Cleaning  
Cleaning the Printhead  
Always use a new cleaning pen on the printhead (an old pen carries contaminants from its  
previous uses that may damage the printhead).  
Caution • The printhead becomes hot while printing. To protect from damaging the  
printhead and risk of personal injury, avoid touching the printhead. Use only the cleaning  
pen to perform maintenance.  
When you load new media, you can also clean the printhead.  
1. Rub the cleaning pen across the dark area of the printhead. Clean from the middle to the  
outside. This will move adhesive transferred from the edges of media to the printhead  
outside of media path.  
2. Wait one minute before closing the printer.  
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Maintenance  
Cleaning  
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Media Path Considerations  
Use a cleaning swab to remove debris, dust or crust that has built-up on the holders, guides and  
media path surfaces.  
1. Use the alcohol in the cleaning swab to soak the debris to break up the adhesive.  
2. Wipe the ridges to remove accumulated debris.  
3. Wipe the inside edges of both edge guides to remove any built-up residue.  
4. Wait one minute before closing the printer.  
Discard the cleaning swab after use.  
Media  
Guides  
Platen  
Ridges  
Peel  
Bar  
Pinch  
Roller  
Ridges  
Ridges  
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Cleaning  
Sensor Cleaning  
Dust can accumulate on the media sensors.  
1. Gently brush or blow dust away with a can of compressed air. Do not use an air  
compressor - oil (from the pump) and dirty water will contaminate the printer and  
printhead. If necessary, use a dry swab to brush away dust. If adhesives or other  
contaminates remain, use an alcohol moistened swab to break it up.  
2. Use a dry swab to remove any residue that may be left from the first cleaning.  
3. Repeat steps 1 and 2 as required until all residue and streaks are removed from the sensor.  
.
Ribbon Trailer  
Sensor  
Gap  
Sensor  
Black-Line  
Sensor  
Label Taken  
Sensor  
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Maintenance  
Cleaning  
58  
Platen Cleaning and Replacement  
The standard platen (drive roller) normally does not require cleaning. Paper and liner dust can  
accumulate without effecting print operations. Contaminates on the platen roller can damage  
the printhead or cause the media to slip or stick when printing. Adhesive, dirt, general dust,  
oils and other contaminates should be cleaned immediately off the platen.  
Clean the platen (and media path) whenever the printer has significantly poorer performance,  
print quality or media handling. The platen is the print surface and drive roller for your media.  
If sticking or jamming continues even after cleaning, you must replace the platen.  
The platen can be cleaned with a fiber-free swab (such as a Texpad swab) or a lint free, clean,  
damp cloth very lightly moistened with medical grade alcohol (90% pure or better).  
1. Open the cover (and dispenser door). Remove media from platen area.  
2. Pull the platen bearing latch release tabs on the right and left sides towards the front of the  
printer and rotate them up.  
Platen Bearings  
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Cleaning  
3. Lift the platen out of the printer’s bottom frame.  
4. Clean the platen with the alcohol moistened swab. Clean from the center out. Repeat this  
process until the all of the roller surface has been cleaned. If there has been heavy  
adhesive build-up or label jam, repeat with a new swab to remove residual contaminates.  
Adhesives and oils, for example, may be thinned by the initial cleaning but not completely  
removed.  
5. Install the platen in the printer. Discard the cleaning swabs after use - do not reuse.  
6. Make sure the bearings and drive gear are on the shaft of the platen.  
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Cleaning  
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7. Align the platen with the gear to the left and lower it into the printer’s bottom frame.  
8. Rotate the platen bearing latch release tabs down on the right and left sides towards the  
rear of the printer and snap them into place.  
Allow the printer to dry for one minute before closing the dispenser door, media cover or  
loading labels.  
Other Printer Maintenance  
There are no user level maintenance procedures beyond those detailed in this section. See the  
Troubleshooting on page 65 for more information on diagnosing printer and print problems.  
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Maintenance  
Replacing the Printhead  
61  
Replacing the Printhead  
If you need to replace the printhead, read the procedure and review the removal and  
installation steps before actually replacing the printhead.  
Caution • Prepare your work area by protecting against static discharge. Your work area  
must be static-safe and include a properly grounded conductive cushioned mat to hold the  
printer and a conductive wrist strap for yourself.  
Caution • Turn the printer power off and unplug the power cord before replacing the  
printhead.  
Before following the steps in this procedure, open the printer by pulling the release latches  
forward then lifting the top cover.  
Printhead Removal  
1. Open the printer. Remove any transfer ribbon from the printer  
2. .Grasp the print head spring and pull it to the left; then, slide it free of the carriage.  
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Maintenance  
Replacing the Printhead  
62  
3. Use the spring to pry the printhead clip off the right side of the carriage.  
.
4. Pull the printhead and bracket forward.  
.
5. Use a #2 Phillips driver to remove the screw that holds the ground wire.  
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Maintenance  
Replacing the Printhead  
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6. Unplug both bundles of printhead wires from their connectors.  
Replacing the Printhead  
The new print head comes with the clip and ground screw attached.  
1. Align the printhead and bracket to plug the left and right connectors into the black and  
white wire bundles.  
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Replacing the Printhead  
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2. Attach the ground wire and secure it with the screw. Use a #2 Phillips driver to tighten it.  
3. Slip the left end of the printhead spring into the left side of the ribbon carriage; then slide  
the right end into the other side. The angle of the “V” fits into the indent on top of the  
printhead bracket.  
4. Insert the bracket pegs into the left side of the carriage.  
5. Align the right side of the bracket and insert the printhead clip through the right side of the  
ribbon carriage into the bracket.  
6. Verify that the printhead moves up and down freely when pressure is applied and remains  
locked when released.  
7. Clean the printhead. Use a new pen to wipe body oils (finger prints) and debris of the  
printhead. Clean from the center of the printhead to the outside. See Cleaning the  
8. Reload media. Plug in the power cord, turn on the printer and print a status report to  
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Status Light Descriptions  
Status Light Descriptions  
What the Status Light is Telling You  
Fora Resolution,  
Refer to Number:  
LED Status and Color  
Printer Status  
Off  
Solid Green  
Off  
On  
1
2
Solid Amber  
Stopped  
3
Flashing Green  
Normal Operation  
Stopped  
4
Flashing Red  
5
Double Flashing Green  
Flashing Amber  
Paused  
6
Paused  
7
Alternately Flashing Green and Red  
Flashing Red, Red and Green  
Needs Service  
Needs Service  
8
9
Flashing Red, Amber Green  
Memory  
10*  
(* - Do NOT reset or turn off power!)  
Defragmentation  
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Status Light Error Resolutions  
Status Light Error Resolutions  
The following Status Error Light Resolution numbers correspond to the Status Light  
Description table on the previous page. Each error number may have one or more resolution to  
correct that error listed.  
1. The printer is not receiving power.  
• Have you turned on the printer power?  
• Check power connections from the wall outlet to the power supply, and from the power  
supply to the printer. See Attaching Power on page 10.  
• Disconnect the printer from the wall outlet for 30 seconds and then reconnect the printer to  
the wall outlet.  
2. The printer is on and in an idle state.  
No action necessary.  
3. The printer has failed its power on self test (POST).  
• If this error occurs right after you turn on the printer, contact an authorized reseller for  
assistance. When the printer is operating normally, the printer status light will be amber  
for about 10 seconds before turning green (solid or blinking).  
There is a memory error.  
• If this error occurs after you have been printing, turn the printer power off and on, and  
then resume printing.  
The printhead needs to cool down.  
• If this error continues, turn the printer power off for five minutes or more, and then turn  
on. If the amber light persists, then the printer requires service.  
4. The printer is receiving data.  
• As soon as all of the data has been received, the status LED will turn green and the printer  
will automatically resume operation.  
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Status Light Error Resolutions  
5. The media is out.  
• Follow the instructions for Loading Roll Media on page 11 in the Getting Started section,  
and then press the Feed button to resume printing.  
The ribbon is out.  
• The printer has sensed the end of the ribbon roll. Replace the ribbon.  
The printhead is open.  
• Close the top cover and then press the Feed button to resume printing.  
6. The printer is paused.  
• Press the Feed button to resume printing.  
7. The printhead is over temperature.  
• Printing will stop until the printhead cools to an acceptable printing temperature. When it  
does, the printer will automatically resume operation.  
8. FLASH memory is not programmed.  
• Return the printer to an authorized reseller.  
9. The printhead or motor has had a critical failure.  
• Return the printer to an authorized reseller.  
10. The printer is defragmenting memory.  
Caution • Do NOT turn off the printer power during defragmentation. Doing so can damage  
the printer.  
• Defragmentation is a normal operation of the printer – necessary to manage the memory  
space for optimal use. The printer will defragment its memory both after a factory default  
and when the printer detects that a defragment is required.  
When the printer is in this condition, allow it to finish defragmenting. If this warning occurs  
frequently, check the label formats. Formats that frequently and repeatedly write to and  
erase from memory my cause the printer to defragment often. Using formats that avoid  
frequent and repeated memory write/erase event will minimize the need for  
defragmentation.  
• If this warning condition does not go away, contact Technical Support. The printer  
requires service.  
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Print Quality Problems  
Print Quality Problems  
No print on the label.  
• The media may not be direct thermal media which is required when printing without  
ribbon (i.e. thermal transfer). See the test procedure Determining Thermal Media Types  
• The wrong side of the media is facing up contacting the printhead. The media roll may not  
be outside wound.  
• Transfer ribbon - The outside of the ribbon must be outside wound - the transfer material  
facing out. See the following ribbon test procedures: Ribbon Test with Adhesive  
• Is the media loaded correctly? Follow the instructions for Loading Roll Media on page 11  
in the Getting Started section. For printing using transfer ribbon, see Loading Transfer  
The printed image does not look right.  
• The printhead is dirty. Clean the printhead.  
• The printhead is under temperature.  
• Adjust the print darkness and/or print speed.  
Use the ^PR(speed) and ~SD(darkness) commands referenced in the ZPL  
Programming Guide.  
Use the D(darkness/density) and S (speed) commands in the EPL Programmers  
Guide.  
Manually adjust print darkness with the six-flash sequence of Feed Button Modes  
The Windows printer driver or application software may change these settings and  
may require a change to optimize print quality.  
• The media being used is incompatible with the printer. Be sure to use the recommended  
media for your application, and always use Zebra-approved labels and tags.  
• The printhead has worn out. The printhead is a consumable item and will wear out due to  
friction between the media and printhead. Using unapproved media may shorten life or  
damage your printhead. Replace the printhead.  
• The platen may need cleaning or replacement. The platen (driver) roller maybe losing  
traction due to:  
Foreign objects attached to its surface,  
The rubbery smooth surface has become polished and slippery, or  
There is damage to the normally smooth and flat print surface such as box knife cuts.  
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Print Quality Problems  
There are long tracks of missing print (blank vertical lines) on  
several labels.  
• The printhead is dirty. Clean the printhead.  
• The printhead elements are damaged.  
The printing does not start at the top of the label or misprinting of  
one to three labels.  
• The media may not be threaded correctly. Follow the instructions for Loading Roll Media  
on page 11 in the Getting Started section.  
• The printer needs to be calibrated. Refer to the two-flash sequence of Feed Button Modes  
on page 76 in this section.  
• ZPL Label Formats - The correct media sensor may not be activated. Manual calibration  
selects the media sensing method for the labels being used (refer to the ^MNcommand in  
the ZPL Programming Guide).  
• ZPL Label Formats - Verify that the Label Top (^LT) command is correctly set for your  
application (consult the ZPL Programming Guide).  
• EPL Label Formats - The correct media sensor may not be activated for label dispensing,  
blackline or notch sensing, or for Gap/Web sensing. Manual calibration selects the media  
sensing method for the labels being used (refer to the Oand Q commands in the EPL  
Programmers Guide).  
• EPL Label Formats - Verify that the Set Label Length (Q) command is correctly set for  
your application (consult the EPL Programmers Guide).  
A ZPL label format was sent to, but not recognized by, the printer.  
• Is the printer in pause mode? If so, press the Feed button.  
• If the status LED is on or flashing, refer to What the Status Light is Telling You on page 66.  
• Make sure the data cable is correctly installed.  
• A communications problem has occurred. First, make sure that the correct  
communications port on the computer is selected. Refer to Connecting your Printer to a  
Computer on page 22 in the Getting Started section.  
Verify the correct Format and Control Prefix on the printer match what you are using in  
your ZPL programmed label format. The default Format (COMMAND CHAR) is Caret  
(^) character and the Control (CONTROL CHAR) is a Tilde (~) character. Verify the  
characters with the Configuration Status label printout. Refer to the one-flash sequence of  
Feed Button Modes on page 76 to print this label.  
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Print Quality Problems  
A EPL label format was sent to, but not recognized by, the printer.  
• Is the printer in pause mode? If so, press the Feed button.  
• If the printer has label dispensing enabled, the printer may be waiting for the label to be  
removed. The liner/web must be properly threaded through the label dispenser mechanism  
(peeler) to correctly operate in label dispense mode, refer to Label Dispenser Option  
• If the status LED is on or flashing, refer to What the Status Light is Telling You on page 66.  
• Make sure the data cable is correctly installed.  
• A communications problem has occurred. First, make sure that the correct  
communications port (USB) on the computer is selected. Refer to Connecting your  
Printer to a Computer on page 22 in the Getting Started section.  
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Manual Calibration  
Manual Calibration  
Manual calibration is recommended whenever you are using pre-printed media or if the printer  
will not correctly auto calibrate.  
1. Make sure media is loaded.  
2. Turn on the printer power.  
3. Press and hold the Feed button until the green status light flashes once, then twice and  
then continuing until the flash groups reach the group of seven flashes. Release the Feed  
button.  
4. The printer will set the media sensor for the label backing being used. After it is done  
making this adjustment, the roll will automatically feed until a label is positioned at the  
printhead. A profile of the media sensor settings (similar to the example below) will print.  
Upon completion, the printer will save the new settings in memory and the printer is ready  
for normal operation.  
5. Press the Feed button. One entire blank label will feed. If this does not happen, try  
defaulting (refer to the four-flash sequence in “Feed Button Modes” later in this chapter)  
and recalibrating the printer.  
Note • Performing a manual calibration disables the auto calibration function. To return to  
auto calibration, default the printer (refer to the four-flash sequence in Feed Button Modes  
on page 76 in this section).  
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Troubleshooting Tests  
Troubleshooting Tests  
Printing a Configuration Label  
To print out a listing of the printer’s current configuration, refer to the one-flash sequence in  
to interpret the label.  
Recalibration  
Recalibrate the printer if it starts to display unusual symptoms, such as skipping labels. Refer  
to the two-flash sequence in Feed Button Modes on page 76 in this section.  
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Resetting the Factory Default Values  
Resetting the Factory Default Values  
Sometimes, resetting the printer to the factory defaults may solve some problems. Refer to the  
four-flash sequence in Feed Button Modes on page 76 in this section.  
Communications Diagnostics  
If there is a problem transferring data between the computer and printer, try putting the printer  
in the communications diagnostics mode. The printer will print the ASCII characters and their  
respective hexadecimal values (a sample is shown below) for any data received from the host  
computer. To find out how,  
There are multiple ways to enter hex data dump mode:  
• The ~JDZPL command  
• The dumpEPL command  
• On power up with the Feed button pressed. Refer to the power off mode procedure in Feed  
Button Modes on page 76 in this section.  
The printer will print ‘Now in DUMP’ (see below) and advance to the top of the next label.  
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Communications Diagnostics  
The following example of a communications DUMP mode printed out. The printout displays  
hexadecimal data 00h-FFh (0-255 decimal) with a unique character for each hexadecimal  
value displayed above the hexadecimal data.  
The blank lines between the lines of data are where serial port and Bluetooth data handling  
errors get logged. The errors are:  
F = Frame Error  
P = Parity Error  
N = Noise Error  
O = Data Overrun Error  
To exit the diagnostic mode and resume printing, turn off and then turn on the printer. An  
alternate method for exiting the diagnostic mode is to press the Feed button as many times as it  
takes to clear the printer’s command buffer and print ‘Out of DUMP’ on the label.  
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Feed Button Modes  
Feed Button Modes  
Power Off Modes  
With the printer power off, press and hold the Feed button while you turn on the power.  
Flash Sequence  
Action  
Firmware Download Mode - The printer starts rapidly flashing red to denote entry into  
the Firmware Download mode. Releasing the Feed button here will start initializing the  
printer for download. The printer is ready to start downloading firmware when the status  
light begins to slowly flash between red and green.  
Amber - Red  
Flashing  
(and File) Download utility available for use with this printer. Firmware updates for your  
printer, if available, are posted on the Zebra on our web site at:  
www.zebra.com  
Normal Operations Mode - The printer continues into a normal printer initialization.  
Releasing the Feed button here will allow the printer to start normally without firmware  
download or operating in communications diagnostics mode.  
Amber  
Green  
Communications Diagnostic (Dump) Mode - Release the Feed button immediately after  
the printer status light turns green. The printer will print ‘Now in DUMP’ at the top of the  
label and then advance to the next label. After printing the first label, the printer will  
automatically enter into diagnostic mode in which the printer prints out a literal  
representation of all data subsequently received.  
To exit the diagnostic mode and resume printing, turn off and then turn on the printer. An  
alternate method for exiting the diagnostic mode is to press the Feed button as many times  
as it takes to clear the printers command buffer and print ‘Out of DUMP’ on the label.  
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Feed Button Modes  
Power On Modes  
With the printer power on and top cover closed, press and hold the Feed button for several seconds. The green status  
LED will flash a number of times in sequence. The explanation at the right (Action) shows what happens when you  
release the key after the start specific number of flashes and before the next flash sequence starts.  
Flash Sequence  
Action  
Configuration Status - Prints a detailed printer configuration status label. The label can be used  
to verify printing, assist printer to computer communication configuration, maintenance,  
troubleshooting, and help us with customer care communications.  
*
Standard Auto Media Calibration - The printer detects and sets media type and media length,  
and it adjusts the media sensors for optimal performance with the installed media (equivalent ZPL  
command ~JC). The printer will feed one to four labels while calibrating.  
*
**  
Note: Users familiar with the Zebra EPL desktop printer use this Feed mode to replace power-up  
AutoSensing calibration (equivalent EPL command XA).  
Serial Port Configuration - Applies only to printers with serial interface ports.  
To reset the serial port communication parameters, except for Flow Control. Press and release the  
Feed button while the LED rapidly flashes amber and green.  
*
**  
***  
For autobaud synchronization: Send the ^XA^XZcommand sequence to the printer while the LED  
rapidly flashes amber and green. When the printer and host are synchronized, the LED changes to  
solid green. NOTE: No labels will print during autobaud synchronization.  
Factory Defaults - Resets the printer to the factory default settings (equivalent to ZPL command  
^JUN). See Appendix: ZPL Configuration on page 87 for a description of the primary  
configuration settings and their associated ZPL commands. Some configuration settings are not  
returned to their initial ‘out of box’ settings. Other settings are exclusively set, viewed and  
controlled by programming are also reset. The printer then performs a standard media calibration  
followed by .a memory defragmentation routine.  
*
**  
***  
****  
Print Width Adjustment - Prints a succession of boxes starting at the minimum print width and  
ending in the printer’s maximum print width in 4mm increments. Press the Feed button once when  
the printer has reached the desired maximum print width. Note that the printer driver and  
applications can override this setting.  
*
**  
***  
****  
*****  
Print Darkness (Density) Adjustment - Prints a succession of bar code simulation patterns  
starting at the minimum darkness (print density/heat) and ending in the printer’s maximum  
darkness in increments of four (4) using the ZPL darkness setting range values. Press the Feed  
button once the pattern is clear and legible. Do not continue to increase the darkness setting or  
bar code line widths may become distorted reducing readability. Note that the printer driver and  
applications can override this setting.  
*
**  
***  
****  
*****  
******  
Manual Media Calibration - The printer runs extensive tests to detect and set media type and  
media length, and then it adjusts the media sensors for optimal performance with the installed  
media (equivalent ZPL command ~JG). Manual calibration is recommended whenever you are  
using pre-printed media, print on the liner or if the printer will not correctly auto calibrate. A  
graphical profile of the media sensing will print. See Manual Calibration on page 72 for more  
details and considerations.  
*
**  
***  
****  
*****  
******  
*******  
If the Feed button remains pressed after 7th flash sequence cycle finishes, the printer exits the  
configuration mode when the Feed button is released.  
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Feed Button Modes  
Notes • ___________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
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Universal Serial Bus (USB) Interface  
Universal Serial Bus (USB) Interface  
The figure below displays the cable wiring required to use the printer’s USB interface.  
The printer requires cable or cable packaging that bears the “Certified USB™” mark to  
guarantee USB 2.0 compliance.  
Pin  
Signal  
1
2
Vbus - N/C  
2
3
1
4
D-  
D+  
3
4
Ground  
Shell  
Shield / Drain Wire  
For printer supported operating systems and drivers, see the software and documentation CD  
or visit the Zebra Web site at:  
http://www.zebra.com  
For information on the USB interface, go to the USB web site at:  
http://www.usb.org  
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Parallel Interface  
Parallel Interface  
The printer’s parallel interface uses the IEEE 1284-A to 1284-B parallel interface cables. the  
host connector has a DB-25 pin male connector. The printer connector is a Centronics style  
connector.  
DB-25  
Pin No.  
Centronics  
Pin No.  
HOST  
PRINTER  
STROBE~  
DATA 0  
DATA 1  
DATA 2  
DATA 3  
DATA 4  
DATA 5  
DATA 6  
DATA 7  
ACK~  
BUSY  
PAPER ERR.  
SELECT  
AUTOFD~  
ERROR~  
N/A  
STROBE~  
DATA 0  
DATA 1  
DATA 2  
DATA 3  
DATA 4  
DATA 5  
DATA 6  
DATA 7  
ACK~  
BUSY  
PAPER ERR.  
SELECT  
AUTOFD~  
n/c  
SIG. GND  
CHAS GND  
+5V  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
n/c  
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
9
9
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
32  
33  
34  
35  
36  
N/A  
N/A  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
SIG. GND  
ERROR~  
SIG. GND  
n/c  
n/c  
SELECTIN~  
DB-25 to Centronics  
(Cable)  
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Serial Port Interface  
Serial Port Interface  
Pin  
1
Description  
Not used  
2
3
4
RXD (receive data) input to the printer  
TXD (transmit data) output from the printer  
DTR (data terminal ready) output from the printer -- controls  
when the host may send data  
5
6
7
Chassis ground  
DSR (data set ready) input to the printer  
RTS (request to send) output from the printer -- always in the  
ACTIVE condition when the printer is turned on  
CTS (clear to send) - Not used by the printer  
+5 V @ 0.75 A fused  
8
9
The maximum current available through the serial and/or parallel port is not to  
exceed a total of 0.75 Amps.  
When XON/XOFF handshaking is selected, data flow is controlled by the ASCII  
control codes DC1 (XON) and DC3 (XOFF). The DTR control lead will have no  
effect.  
Interconnecting to DCE Devices — When the printer is connected via its RS-232  
interface to data communication equipment (DCE) such as a modem, a STAN-  
DARD RS-232 (straight-through) interface cable must be used. Figure 32 shows  
the connections required for this cable.  
Connecting to the KDU (Keyboard Display Unit) — The KDU was designed for  
DCE printer connections and requires a Zebra custom serial port gender changing  
adapter. The KDU now includes the KDU adapter and the Zebra kit part number  
for the KDU Adapter is 105934-088.  
Connecting the Printer to a DCE Device  
DB-25S  
DB-9P  
DB-9S  
DB-9P  
Connector  
to DCE Device  
Connector  
to Printer  
Connector  
to DCE Device  
Connector  
to Printer  
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B
Appendix: Dimensions  
This section provides external printer dimensions.  
Contents  
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External GC420t™ Printer Dimensions  
External GC420t™ Printer Dimensions  
All dimensions are  
in inches  
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External GC420t™ Printer Dimensions  
Optional: Label Dispenser  
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External GC420t™ Printer Dimensions  
Notes • ___________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
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Appendix: ZPL  
Configuration  
This section provides a basic overview of managing printer configuration, the Configuring  
Status Printout, and Printer Memory Printouts.  
Contents  
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Managing the ZPL Printer Configuration  
Managing the ZPL Printer Configuration  
The ZPL printer is designed to allow you to change printer settings dynamically for fast first  
label out printing. Printer parameters that are persistent, will be retained for following formats  
to use. Those settings will remain in effect until they are changed by subsequent commands,  
the printer is reset, power is cycled, or when you restore a parameter that has a factory default  
by using the Feed Button Mode four (4) flash routine. The ZPL Configuration Update  
command (^JU) saves and restores printer configurations to initialize (or re-initialize) the  
printer with pre-configured settings.  
To keep settings after a power cycle or printer reset, a ^JUScan be sent to the printer  
to save all current persistent settings.  
The values are recalled with a ^JURcommand to restore the last saved values to you  
printer.  
ZPL stores all parameters at once with a single command discussed above. The legacy EPL  
programming language (supported by this printer) changes and saves individual commands  
immediately. Most configuration and settings are shared between ZPL and EPL. For example,  
changing the speed setting with EPL will also change the speed set for ZPL operations. The  
changed EPL setting will persist even after a power cycle or reset issued by either printer  
language.  
To assist the developer, the printer has a listing of the operating parameters, a Printer  
Configuration Label. It can be accessed by using the printer’s Feed button and the Printing a  
Test (Printer Configuration) Label on page 19. The Zebra Setup Utility and the  
ZebraDesigner™ Windows driver also print this label and other printer status labels to help  
you manage your printer.  
ZPL Printer Configuration Format  
Managing more than one printer can be done creating a printer configuration programming file  
to send to one or more printers or ZebraNet™ Bridge can be used to clone a printer’s setup.  
Figure 1 below shows the basic structure of a ZPL programming configuration file.  
See the ZPL programmer’s guide and the ZPL Configuration Status to Command Cross-  
reference on page 89 to create a programming file. The Zebra Setup Utility (ZSU) can be used  
to send programming files to the printer. Windows Notepad (text editor) can be used to create  
programing files.  
Figure 1 • Configuration Parameter Format Structure  
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ZPL Configuration Status to Command Cross-reference  
ZPL Configuration Status to Command Cross-reference  
The Printer Configuration Label, shown below, provides a listing of a majority of the  
configurations settings that can be set by ZPL command.  
Figure 2 • Configuration Label Printout  
Sensor Settings  
used for Service  
Purposes  
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ZPL Configuration Status to Command Cross-reference  
Table 2 • ZPL Commands and Configuration Receipt Callout Cross-Reference  
Command  
~SD  
Listing Name  
DARKNESS  
Description  
Default: 10.0  
^PR  
PRINT SPEED  
TEAR OFF  
Default: 6 IPS / 152.4 mm/s (max.)  
Default: +000  
~TA  
^MN  
MEDIA TYPE  
SENSOR TYPE  
SENSOR SELECT  
PRINT METHOD  
PRINT WIDTH  
LABEL LENGTH  
Default: GAP/NOTCH  
Default: WEB  
Default: AUTO (^MNA- Auto-Detect)  
THERMAL-TRANS or DIRECT-THERMAL  
Default: 832 (dots)  
^MT  
^PW  
^LL  
Default: 1225 (dots) (the value constantly re-  
calibrates with automatic Web-Gap detection for  
label media)  
^ML  
MAXIMUM  
LENGTH  
Default: 39.0IN 989MM  
USB COMM.  
Connection Status: Connected / Not Connected  
PARALLEL COMM. Connection Available:  
BIDIRECTIONAL  
^SCa  
^SC,b  
^SC,,c  
BAUD  
Default: 9600  
DATA BITS  
PARITY  
Default: 8 BITS  
Default: NONE  
^SC,,,,e HOST HANDSHAKE Default: DTR & XON/XOFF  
^SC,,,,,f PROTOCOL Default: NONE  
SER COMM. MODE Default: AUTO  
CUTTER TYPE  
^CT / ~CT CONTROL CHAR  
^CC / ~CC COMMAND CHAR  
^CD / ~CD DELIM./CHAR  
Option Present: LINER/TAG FULL (cut)  
Default: <~> 7EH  
Default: <^> 5EH  
Default: <,> 2CH  
Default: ZPL II  
^SZ  
^MFa  
^MF,b  
~JS  
ZPL MODE  
MEDIA POWER UP  
HEAD CLOSE  
BACKFEED  
Default: NO MOTION  
Default: FEED  
Default: DEFAULT  
Default: +000  
^LT  
LABEL TOP  
^LS  
LEFT POSITION  
Default: +0000  
~JD / ~JE HEXDUMP  
Default: NO (~JE)  
From this point in the Configuration Receipt listing, the printout has sensor settings and values  
are displayed to troubleshoot sensor and media operations. These are typically used by Zebra  
Tech Support to diagnose printer problems.  
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ZPL Configuration Status to Command Cross-reference  
The configuration settings listed here resume after the TAKE LABEL sensor value. These  
listings contain printer features seldom changed from default or provide status information  
(e.g. Firmware Version).  
Table 3 • ZPL Commands and Configuration Receipt Callout Cross-Reference  
Command  
Listing Name  
Description  
^MP  
MODES ENABLED  
Default: CWF (See ^MPCommand)  
(CWFM for wireless printers with display)  
MODES DISABLED  
RESOLUTION  
Default: (nothing set)  
^JM  
Default: 832 8/mm FULL (203 dpi)  
1280 8/mm FULL (300 dpi)  
FIRMWARE  
Lists ZPL Firmware Version  
XML SCHEMA  
HARDWARE ID  
CONFIGURATION  
RAM  
1.3  
Lists Firmware Boot-block Version  
CUSTOMIZED (after first use)  
2104k........ R:  
OPTION MEMORY  
ONBOARD FLASH  
FORMAT CONVERT  
65536k.......B: (only displays this if installed)  
1536k.........E:  
NONE  
^MU  
^JI / ~JI ZBI  
DISABLED (Requires key to enable)  
2.1  
ZBI VERSION  
^JH  
^MA  
~RO  
LAST CLEANED  
HEAD USAGE  
X,XXX IN  
X,XXX IN  
TOTAL USAGE  
RESET CNTR1  
RESET CNTR1  
SERIAL NUMBER  
EARLY WARNING  
X,XXX IN  
X,XXX IN  
X,XXX IN  
XXXXXXXXXXX  
MAINT. OFF  
^JH  
The printer has the ability to set a command or a group of commands once for all receipts (or  
labels) that follow. Those settings will remain in effect until they are changed by subsequent  
commands, the printer is reset, or you restore factory defaults.  
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Printer Memory Management and Related Status Reports  
Printer Memory Management and Related Status Reports  
To help you manage printer resources, the printer supports a variety format commands to  
manage memory, transfer objects (between memory areas, import and export), object naming,  
and provide various printer operating status reports. They are very similar to the old DOS  
commands like DIR (directory listing) and DEL (delete file). The most common reports are  
also part of the Zebra Setup Utility and ZebraDesigner™ Windows driver.  
Figure 3 • Memory Management Format Structure  
It is recommended that a single command be processed within a this type of format (form). A  
single command is easily reused as a maintenance and development tool.  
Many of the commands that transfer objects, manage and report on memory are control (~)  
commands. They do not need the be within a format (form). They will be process immediately  
upon receipt by the printer whether in a format (form) or not.  
Note • To maximize available printer memory, the printer includes an automatic memory  
defragmentation (defrag). Several factors can trigger a defrag operation. Changing memory  
by deleting or adding objects to memory can cause a defrag. The printer status light will  
begin flashing Red, Amber and Green when a memory defrag is in process. Do not turn off  
the printer’s power while the status light is flashing. This operation may take several minutes  
if memory use and file fragmentation are high.  
ZPL Programming for Memory Management  
ZPL has various printer memory locations that are used to run the printer, assemble the print  
image, store formats (forms), graphics, fonts and configuration settings.  
ZPL treats Formats (Forms), Fonts, and Graphics like files; and memory locations  
like disk drives in the DOS operating system environment:  
Memory Object Naming: Up to sixteen (16) alphanumeric characters followed  
by a three (3) alphanumeric character file extension:  
i.e. 123456789ABCDEF.TTF  
Legacy ZPL printers with V60.13 firmware and earlier can only use the 8.3 file  
name format verses today’s 16.3 file name format.  
Allows moving objects between memory locations and deleting objects.  
Supports DOS directory style file list reports as printouts or status to the host.  
Allows use of ‘wild cards’ (*) in file access  
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Printer Memory Management and Related Status Reports  
Table 4 • Object Management and Status Report Commands  
Command  
Name  
Description  
^WD  
Print Directory Label  
Prints a list of objects and resident bar codes and  
fonts in all addressable memory locations  
~WC  
Print Configuration  
Label  
Prints a configuration Status Receipt (Label)  
Same as Feed Button mode one flash routine  
^ID  
^TO  
Object Delete  
Deletes objects from printer memory  
Transfer Object  
Used to copy an object or group of objects from  
one memory area to another.  
^CM  
^JB  
~JB  
~DY  
Change Memory Letter  
Designation  
Reassigns a letter designation to a printer  
memory area.  
Initialize Flash memory  
Similar to formatting a disk - erases all objects  
from the specified memory locations B: or E: .  
Reset Optional Memory Similar to formatting a disk - erases all objects  
from the B: memory (factory option).  
Download Objects  
Downloads and installs wide variety of printer  
usable programming objects: fonts (OpenType  
and TrueType), graphics, and other object data  
types.  
Recommendation: Use ZebraNet™ Bridge for  
downloading graphics and fonts in the printer.  
~DG  
^FL  
Download Graphic  
Font Linking  
Downloads an ASCII Hex representation of a  
graphic image. This is used by ZebraDesigner™  
(label creation application) for graphics.  
Appends secondary TrueType font or fonts to the  
primary TrueType font to add glyphs  
(characters).  
^LF  
^CW  
List Font Links  
Font Identifier  
Prints a list of the linked fonts  
Assigns a single alphanumeric character as an  
alias to a font stored in memory.  
Important • Some factory installed ZPL fonts in your printer cannot be copied, cloned or  
restored to your printer by reloading or updating firmware. If these license restricted ZPL fonts  
are removed by an explicit ZPL object delete command, they must be repurchased and  
reinstalled via a font activation and installation utility. EPL fonts do not have this restriction.  
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Printer Memory Management and Related Status Reports  
Notes • ___________________________________________________________________  
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__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
__________________________________________________________________________  
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GC420t™ User Guide  
5/22/2012  
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