LabelZone Zebra Gc420T User Guide (en) Manual

GC420t to the manual 9f6d61d1-dd17-41b3-81b5-6b8250741116

2017-09-13

User Manual: LabelZone Zebra Gc420T

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Zebra® GC420t™
Desktop Thermal Printer

User Guide

ii

P1052686-001

GC420t™ User Guide

5/22/2012

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:
Web address: www.zebra.com/environment

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About This Document

This section provides you with contact information, document structure and organization, and
additional reference documents.

Contents
Who Should Use This Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
How This Document Is Organized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vii
Document Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

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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:

P1052686-001

Section

Description

Introduction on page 1

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.

Getting Started on page 9

This section describes how to set up your printer
for the first time and use the most common
operating procedures for loading media.

Print Operations on page 29

This section provides media and print handling,
font and language support, and the set up of less
common printer configurations.

Printer Options on page 45

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.

Maintenance on page 53

This section provides routine cleaning and
maintenance procedures.

Troubleshooting on page 65

This section provides information about printer
error reporting that you might need for printer
troubleshooting. Assorted diagnostic tests are
included.

Appendix: Interface Wiring
on page 79

This section provides additional interface
information and wiring diagrams to assist with
printer to host system integration (typically a PC).

Appendix: Dimensions on page 83

This section provides external printer dimensions
for the standard printer and printer with options.

Appendix: ZPL Configuration
on page 87

This section briefly covers printer configuration
and includes a cross-reference to ZPL printer
configuration commands.

GC420t™ User Guide

5/22/2012

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: emb@zebra.com
Subject line: Emaillist
Self Service Knowledge Base: www.zebra.com/knowledgebase
Online Case Registration: www.zebra.com/techrequest
Which Department
Do You Need?
Regional Headquarters

Europe, Middle East,
and Africa

The Americas
Zebra Technologies Corporation
475 Half Day Road, Suite 500
Lincolnshire, IL 60069 USA
T: +1 847 634 6700
Toll-free +1 866 230 9494
F: +1 847 913 8766

Zebra Technologies Europe
Limited
Dukes Meadow
Millboard Road
Bourne End
Buckinghamshire, SL8 5XF
United Kingdom

Asia Pacific
and India
Zebra Technologies Asia Pacific
Pte. Ltd.
120 Robinson Road
#06-01 Parakou Building
Singapore 068913
T: + 65 6858 0722
F: +65 6885 0838

T: +44 (0) 1628 556000
F: +44 (0) 1628 556001
Technical Support
For questions on the
operation of Zebra
equipment and software,
please call your distributor.
For additional assistance,
contact us.

T: +1 877 ASK ZEBRA (275 9327)
F: +1 847 913 2578

T: +44 (0) 1628 556039
F: +44 (0) 1628 556003

T: +65 6858 0722
F: +65 6885 0838

Hardware: ts1@zebra.com
Software: ts3@zebra.com

E: Tseurope@zebra.com

E: China: tschina@zebra.com
All other areas:
tsasiapacific@zebra.com

T: +1 877 ASK ZEBRA (275 9327)
F: +1 847 821 1797

T: +44 (0) 1772 693069
F: +44 (0) 1772 693046

T: +65 6858 0722
F: +65 6885 0838

E: repair@zebra.com

New requests: ukrma@zebra.com
Status updates:
repairupdate@zebra.com

E: China: tschina@zebra.com
All other areas:
tsasiapacific@zebra.com

T: +44 (0) 1628 556000
F: +44 (0) 1628 556001

T: + 65 6858 0722
F: +65 6885 0838

E: Eurtraining@zebra.com

E: China: tschina@zebra.com
All other areas:
tsasiapacific@zebra.com

T: +44 (0) 1628 556037
F: +44 (0) 1628 556005
E: mseurope@zebra.com

E: China:
GCmarketing@zebra.com
All other areas:
APACChannelmarketing@zebra.c
om

T: +44 (0) 1628 556032
F: +44 (0) 1628 556001

T: +65 6858 0722
F: +65 6885 0836

E: cseurope@zebra.com

E: China: order-csr@zebra.com
All other areas:
csasiapacific@zebra.com

Kiosk printers:
T: +1 866 322 5202
E: kiosksupport@zebra.com

Please have your model and
serial numbers available.
Repair Service
Department
For back-to-base service
and repair.
Technical Training
Department
For Zebra product training
courses.

To request a repair in the U.S.,
go to www.zebra.com/repair.
T: +1 847 793 6868
T: +1 847 793 6864
F: +1 847 913 2578
E: ttamerica@zebra.com

Inquiry Department

T: +1 877 ASK ZEBRA (275 9327)

For product literature and
distributor and dealer
information.

E: inquiry4@zebra.com

Customer Service
Department (US)

T: +1 877 ASK ZEBRA (275 9327)

Internal Sales
Department (UK)

E: clientcare@zebra.com

For printers, parts, media,
and ribbon, please call your
distributor or contact us.
Key:

5/22/2012

T: Telephone
F: Facsimile
E: E-mail

GC420t™ User Guide

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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 Courier New font. For
example, type ZTools to get to the Post-Install scripts in the bin directory.
Files and Directories File names and directories appear in Courier New font. For
example, the Zebra.tar file 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.

P1052686-001

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Contents

About This Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Who Should Use This Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
How This Document Is Organized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Document Conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 • Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
GC420t™ Thermal Printers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What’s in the Box? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unpack and Inspect the Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Your Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printer Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2
3
3
4
5
6

2 • Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Attaching Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Loading Roll Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Preparing Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Placing the Roll in the Media Compartment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Loading Transfer Ribbon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Printing a Test (Printer Configuration) Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Pre-install Windows® Printer Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Plug’N’Play (PnP) Printer Detection and Windows® operating systems . . . . . . . 20
Universal Serial Bus (USB) Device Communications . . . . . . . . . . . . . . . . . . . . . . 21
Serial Port and Windows® operating systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Connecting your Printer to a Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Interface Cable Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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USB Interface Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Serial Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Parallel Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
After Your Printer is Connected. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Testing Communications by Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3 • Print Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Determining Printer Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Long Term Printer In-activity or Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermal Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modes of Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Print Media Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Determining Thermal Media Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adding a New Transfer Ribbon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing a Partially Used Transfer Ribbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting the Print Width. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting the Print Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Media Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ribbon Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
When to Use Ribbon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coated Side of Ribbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

30
30
30
31
31
33
33
33
34
34
34
35
36
36
36

Ribbon Test with Adhesive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Ribbon Scratch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Printing on Fan-Fold Media. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing with Externally Mounted Roll Media. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fonts and Your Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Localizing the Printer with Code Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Identifying Fonts in Your Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stand Alone Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sending Files to the Printer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Print Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38
40
41
41
42
43
44
44

4 • Printer Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Label Dispenser Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zebra® KDU — Printer Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
KDU Plus™ — Printer Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ZBI 2.0™ — Zebra Basic Interpreter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

46
49
50
51

5 • Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Cleaning the Printhead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Media Path Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

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Sensor Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Platen Cleaning and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Other Printer Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Replacing the Printhead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

6 • Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Status Light Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status Light Error Resolutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Print Quality Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing a Configuration Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recalibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resetting the Factory Default Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Communications Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Feed Button Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

66
67
69
72
73
73
73
74
74
76

A • Appendix: Interface Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Universal Serial Bus (USB) Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Parallel Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Serial Port Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Connecting the Printer to a DCE Device 82
B • Appendix: Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
External GC420t™ Printer Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Optional: Label Dispenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
C • Appendix: ZPL Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Managing the ZPL Printer Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

ZPL Printer Configuration Format 88
ZPL Configuration Status to Command Cross-reference . . . . . . . . . . . . . . . . . . . . . . . . . 89
Printer Memory Management and Related Status Reports . . . . . . . . . . . . . . . . . . . . . . . 92
ZPL Programming for Memory Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

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Notes • ___________________________________________________________________

__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________

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1
Introduction

This section describes what you get in your shipping box and provides an overview of printer
features. This includes procedures that describe how to open and close the printer and report
any problems.

Contents
GC420t™ Thermal Printers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
What’s in the Box? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unpack and Inspect the Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Your Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printer Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operator Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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3
3
4
5
6

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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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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:

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•

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-Fold Media
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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Printer Features

Printhead
Ribbon Roll Holders

Ribbon
Take-Up
Gear

Supply
Spindles

Ribbon Motion
Sensor

Take Up
Spindles

Web (Gap)
Sensor

BlackLine
Sensor
Head-Up Sensor
(inside)

Fan-Fold
Media Lock
(screw)

Media Guide
Adjustment
Roll
Holders
Media Guides

Dispenser Option

Platen
Roller
Peel Bar

Dispenser Door
(open)

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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

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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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8

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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Getting Started

This section describes how to set up your printer for the first time and use the most common
operating procedures for loading media.

Contents
Attaching Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading Roll Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Loading Transfer Ribbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing a Test (Printer Configuration) Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pre-install Windows® Printer Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting your Printer to a Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
After Your Printer is Connected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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11
15
19
20
22
27

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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
Cord

Power
Connector
Power
Switch

Active Power
Light

Power
Supply

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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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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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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14

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
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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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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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 Programmer’s 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
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 preinstalled 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 Setup Utilities and Zebra Windows printer drivers are available on the user’s CD and the
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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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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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 nonZebra 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 ^SC command

•

EPL programming Y command

•

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^XZ command 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
^SC command 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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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
Y command to change the printer to the desired settings. Note: the Y command does not
support setting the data flow control, use the Xon/Xoff setting.
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: 9600 baud, 8 bit word length, NO parity, 1 stop bit, and
DTR/XON/XOFF data 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 Y command.
Note • Early models of Zebra® printers running the EPL programming language had 9600

baud, NO parity, 8 data bits, 1 stop bit and a HARDWARE and 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
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
Determining Printer Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Long Term Printer In-activity or Storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Modes of Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Print Media Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting the Print Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting the Print Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Media Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ribbon Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing on Fan-Fold Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Printing with Externally Mounted Roll Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fonts and Your Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stand Alone Printing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sending Files to the Printer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Print Meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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31
33
34
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35
36
38
40
41
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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
Configuration) Label on page 19 to print this label. See Appendix: ZPL Configuration
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 U command.
See the EPL programmer’s guide for more information on the various EPL U commands 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

Non-Continuous
Roll Media

How It Looks

Description

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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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

Thermal transfer. A ribbon is required.

Appears on the media

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 Programmer’s 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 Programmer’s 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 Programmer’s Guide).
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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
Printing a Test (Printer Configuration) Label on page 19 for more details.
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 ^MF command is primarily for automatic
media sensing and calibration. The automatic media calibration that controls the dynamic
media (label to label) calibration is the ^XS command. 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 ^MN parameter for continuous media is set, then the
print does not preform the automatic calibration. The ^MN command 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 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?

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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
paper

The ribbon is coated on the inside and can not be used in
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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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 ^CI command in the ZPL
programmer’s guide.
• For EPL code page support, see the I command 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 ^WD as described above in ZPL Fonts.

• To remove non Asian EPL fonts with EPL programming, use the EK command.
• To remove EPL Asian fonts from the printer, use the ZPL ^ID command.

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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 AUTOFR command can only be disabled with NULL character (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:

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•

EPL command oLY

•

ZPL command ^JH,,,,,E

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4
Printer Options

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.

Contents
Label Dispenser Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zebra® KDU — Printer Accessory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
KDU Plus™ — Printer Accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ZBI 2.0™ — Zebra Basic Interpreter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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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, noncontinuous (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 Programmer’s 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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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*

* - Not real values

50mA

( 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.
ZBI 2.0 can be activated by ordering a ZBI 2.0 Key Kit, or activated by purchasing a key from
the ZBI 2.0 store at www.zebrasoftware.com.
Use the ZDownloader utility to apply the key. Zdownloader is available on the users CD or at
the Zebra Web site: www.zebra.com.

An intuitive ZBI-Developer™ programming utility is used to create, test and
distribute ZBI 2.0 applications is available on the users CD or at the Zebra Web site:
www.zebra.com.

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ZBI 2.0™ — Zebra Basic Interpreter

Notes • ___________________________________________________________________

__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________

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5
Maintenance

This section provides routine cleaning and maintenance procedures.

Contents
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cleaning the Printhead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Media Path Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Platen Cleaning and Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Printer Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacing the Printhead. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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58
60
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Maintenance
Cleaning

Cleaning
When you clean the printer, use one of the following supplies that best suits your needs:
Cleaning Supplies

Order
Quantity

Intended Purpose

Cleaning pens (105950-035)

Set of 12

Clean printhead

Cleaning swabs (105909-057)

Set of 25

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

Interval

Printhead

Let the printhead to cool for a minute, then use a
new cleaning pen to swab the dark line on the
printhead cleaning from the center to the outside
edges of the printhead.
See Cleaning the Printhead on page 55

When using ribbon:
after every roll of
ribbon; when using
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.
See Platen Cleaning and Replacement
on page 58

As needed.

Peel bar
Media path

Clean it thoroughly with 90% medical-grade
alcohol and a fiber-free cleaning swab.
Let alcohol dissipate and the printer dry
completely.

Exterior

Water-dampened cloth.

Interior

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

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

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Maintenance
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

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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Maintenance
Cleaning

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

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

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

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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Maintenance
Replacing the Printhead

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
Printhead on page 55.
8. Reload media. Plug in the power cord, turn on the printer and print a status report to

ensure proper function. See Printing a Test (Printer Configuration) Label on page 19.

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6
Troubleshooting

This section provides information about printer error reporting that you might need for printer
troubleshooting. Assorted diagnostic tests are included.

Contents
Status Light Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status Light Error Resolutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Print Quality Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manual Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resetting the Factory Default Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Communications Diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Feed Button Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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73
74
74
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Status Light Descriptions

Status Light Descriptions
What the Status Light is Telling You

P1052686-001

LED Status and Color

Printer Status

For a Resolution,
Refer to Number:

Off

Off

1

Solid Green

On

2

Solid Amber

Stopped

3

Flashing Green

Normal Operation

4

Flashing Red

Stopped

5

Double Flashing Green

Paused

6

Flashing Amber

Paused

7

Alternately Flashing Green and Red

Needs Service

8

Flashing Red, Red and Green

Needs Service

9

Flashing Red, Amber Green
(* - Do NOT reset or turn off power!)

Memory
Defragmentation

10*

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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
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
on page 33.
• 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
on page 37 and Ribbon Scratch Test on page 37.
• 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
Ribbon on page 15.

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 Programmer’s
Guide.

•

Manually adjust print darkness with the six-flash sequence of Feed Button Modes
on page 76.

•

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:

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•

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 ^MN command 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 O and Q commands in the EPL
Programmer’s Guide).
• EPL Label Formats - Verify that the Set Label Length (Q) command is correctly set for
your application (consult the EPL Programmer’s 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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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
on page 46.
• 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
Feed Button Modes on page 76 in this section. See Appendix: ZPL Configuration on page 87
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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74

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 ~JD ZPL command
• The dump EPL 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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76

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

Amber - Red
Flashing

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.
See Sending Files to the Printer on page 44 for more information on using the Firmware
(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

Amber

Green

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.
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 printer’s 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^XZ command 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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78

Feed Button Modes

Notes • ___________________________________________________________________

__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________

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Appendix: Interface Wiring

This section provides printer interface connection information.

Contents
Universal Serial Bus (USB) Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Parallel Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Serial Port Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

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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.

2

3

1

4

Pin

Signal

1

Vbus - N/C

2

D-

3

D+

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.

HOST

DB-25
Pin No.

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
N/A
N/A
SIG. GND
SIG. GND
SIG. GND
SIG. GND
SIG. GND
SIG. GND
SIG. GND

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25

Centronics
Pin No. PRINTER
1
2
3
4
5
6
7
8
9
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

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
ERROR~
SIG. GND
n/c
n/c
SELECTIN~

DB-25 to Centronics
(Cable)

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82

Serial Port Interface

Serial Port Interface
Pin
1
2
3
4
5
6
7
8
9

Description
Not used
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
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

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 STANDARD 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
Connector
to DCE Device

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DB-9P
Connector
to Printer

DB-9S
Connector
to DCE Device

GC420t™ User Guide

DB-9P
Connector
to Printer

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B
Appendix: Dimensions

This section provides external printer dimensions.

Contents
External GC420t™ Printer Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Optional: Label Dispenser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

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External GC420t™ Printer Dimensions

External GC420t™ Printer Dimensions

All dimensions are
in inches

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Optional: Label Dispenser

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86

External GC420t™ Printer Dimensions

Notes • ___________________________________________________________________

__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________

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C
Appendix: ZPL
Configuration

This section provides a basic overview of managing printer configuration, the Configuring
Status Printout, and Printer Memory Printouts.

Contents
Managing the ZPL Printer Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
ZPL Configuration Status to Command Cross-reference. . . . . . . . . . . . . . . . . . . . . . . . . 89
Printer Memory Management and Related Status Reports . . . . . . . . . . . . . . . . . . . . . . . 92

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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 ^JUS can be sent to the printer
to save all current persistent settings.

•

The values are recalled with a ^JUR command 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 Crossreference 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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90

ZPL Configuration Status to Command Cross-reference

Table 2 • ZPL Commands and Configuration Receipt Callout Cross-Reference
Command

Listing Name

Description

~SD

DARKNESS

Default: 10.0

^PR

PRINT SPEED

Default: 6 IPS / 152.4 mm/s (max.)

~TA

TEAR OFF

Default: +000

^MN

MEDIA TYPE

Default: GAP/NOTCH

SENSOR TYPE

Default: WEB

SENSOR SELECT

Default: AUTO (^MNA - Auto-Detect)

^MT

PRINT METHOD

THERMAL-TRANS or DIRECT-THERMAL

^PW

PRINT WIDTH

Default: 832 (dots)

^LL

LABEL LENGTH

Default: 1225 (dots) (the value constantly recalibrates 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

BAUD

Default: 9600

^SC,b

DATA BITS

Default: 8 BITS

^SC,,c

PARITY

Default: NONE

HOST HANDSHAKE

Default: DTR & XON/XOFF

^SC,,,,e

^SC,,,,,f PROTOCOL

Default: NONE

SER COMM. MODE

Default: AUTO

CUTTER TYPE

Option Present: LINER/TAG FULL (cut)

^CT / ~CT CONTROL CHAR

Default: <~> 7EH

^CC / ~CC COMMAND CHAR

Default: <^> 5EH

^CD / ~CD DELIM./CHAR

Default: <,> 2CH

ZPL MODE

Default: ZPL II

^MFa

MEDIA POWER UP

Default: NO MOTION

^MF,b

HEAD CLOSE

Default: FEED

~JS

BACKFEED

Default: DEFAULT

^LT

LABEL TOP

Default: +000

^LS

LEFT POSITION

Default: +0000

^SZ

~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

MODES ENABLED

Default: CWF (See ^MP Command)
(CWFM for wireless printers with display)

MODES DISABLED

Default: (nothing set)

RESOLUTION

Default: 832 8/mm FULL (203 dpi)
1280 8/mm FULL (300 dpi)

—

FIRMWARE

Lists ZPL Firmware Version

—

XML SCHEMA

1.3

—

HARDWARE ID

Lists Firmware Boot-block Version

—

CONFIGURATION

CUSTOMIZED (after first use)

—

RAM

2104k........ R:

—

OPTION MEMORY

65536k.......B: (only displays this if installed)

—

ONBOARD FLASH

1536k.........E:

FORMAT CONVERT

NONE

^MP

^JM

^MU

^JI / ~JI ZBI

DISABLED (Requires key to enable)

ZBI VERSION

2.1

LAST CLEANED

X,XXX IN

HEAD USAGE

X,XXX IN

TOTAL USAGE

X,XXX IN

RESET CNTR1

X,XXX IN

RESET CNTR1

X,XXX IN

—

SERIAL NUMBER

XXXXXXXXXXX

^JH

EARLY WARNING

MAINT. OFF

—
^JH
^MA
~RO

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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92

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:
•

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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

Object Delete

Deletes objects from printer memory

^TO

Transfer Object

Used to copy an object or group of objects from
one memory area to another.

^CM

Change Memory Letter
Designation

Reassigns a letter designation to a printer
memory area.

^JB

Initialize Flash memory

Similar to formatting a disk - erases all objects
from the specified memory locations B: or E: .

~JB

Reset Optional Memory

Similar to formatting a disk - erases all objects
from the B: memory (factory option).

~DY

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

Download Graphic

Downloads an ASCII Hex representation of a
graphic image. This is used by ZebraDesigner™
(label creation application) for graphics.

^FL

Font Linking

Appends secondary TrueType font or fonts to the
primary TrueType font to add glyphs
(characters).

^LF

List Font Links

Prints a list of the linked fonts

^CW

Font Identifier

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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94

Printer Memory Management and Related Status Reports

Notes • ___________________________________________________________________

__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________
__________________________________________________________________________

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