Bulletin 2755
High Speed Decoder
(Catalog Numbers 2755-DM9 & -DM9E)
User Manual
ALLEN-BRADLEY
Important User Information
Solid state equipment has operational characteristics differing from those of
electromechanical equipment. “Safety Guidelines for the Application,
Installation and Maintenance of Solid State Controls” (Publication SGI-1.1)
describes some important differences between solid state equipment and
hard–wired electromechanical devices. Because of this difference, and also
because of the wide variety of uses for solid state equipment, all persons
responsible for applying this equipment must satisfy themselves that each
intended application of this equipment is acceptable.
In no event will the Allen-Bradley Company be responsible or liable for
indirect or consequential damages resulting from the use or application of
this equipment.
The examples and diagrams in this manual are included solely for illustrative
purposes. Because of the many variables and requirements associated with
any particular installation, the Allen-Bradley Company cannot assume
responsibility or liability for actual use based on the examples and diagrams.
No patent liability is assumed by Allen-Bradley Company with respect to use
of information, circuits, equipment, or software described in this manual.
Reproduction of the contents of this manual, in whole or in part, without
written permission of the Allen-Bradley Company is prohibited.
Throughout this manual we use notes to make you aware of safety
considerations.
ATTENTION: Identifies information about practices or
circumstances that can lead to personal injury or death, property
!
damage, or economic loss.
Attentions help you:
• identify a hazard
• avoid the hazard
• recognize the consequences
Important: Identifies information that is especially important for successful
application and understanding of the product.
PLC is a registered trademark of Allen-Bradley Company, Inc.
Pyramid Integrator, DTL and CVIM are trademarks of Allen-Bradley Company, Inc.
VAX is registered trademark of Digital Equipment Corporation.
Table of Contents
A–B
Using This Chapter
Description of Hardware
Chapter 1
Chapter Objectives 1–1
Overview of This Manual 1–1
Intended Audience 1–2
Conventions Used 1–2
Warnings and Cautions 1–3
Nomenclature 1–3
Related Publications 1–3
Chapter 2
Chapter Objectives 2–1
Differences Between DM9 and DM9E 2–1
Features of the Decoder 2–1
Laser Scan Heads 2–2
Physical Description 2–2
Indicators 2–3
Communications Ports 2–5
Output Modules 2–6
Power and Scan Head Connectors 2–8
Accessories 2–9
How the Decoder Operates
Configuring Your Decoder
Chapter 3
Chapter Objectives 3–1
How the Decoder Operates 3–1
Communications 3–4
RAM and EEPROM Memory 3–7
Operating Modes 3–9
Trigger Ending Conditions 3–10
Response Modes 3–10
Chapter 4
Chapter Objectives 4–1
Initial Programming of the Decoder 4–1
Programming Terminal Cable 4–2
Menu and Setup Screens 4–2
Start–up Procedure 4–4
Select Operation Menu 4–5
Using and Editing the Configuration (Setup) Screens 4–11
Command Bar 4–15
i
Table of Contents
Configuring Your Decoder
Installing the Decoder
Chapter 4
Setup Screen #1 4–17
Setup Screen #1 Fields 4–20
Message Format 4–20
Data Check Characters 4–23
Host Communications 4–24
Package Detect Input 4–27
Setup Screen #2 4–28
Setup Screen #2 Fields 4–31
Bar Code Types 4–31
Code Lengths 4–31
Scanner Control 4–33
Match Code Table 4–40
Outputs 4–41
Input 4–43
Programming Example 4–45
Chapter 5
Chapter Objectives 5–1
Equipment You Will Need 5–1
Electrical Precautions 5–2
How to Handle Excessive Noise 5–2
Grounding Recommendations 5–3
Determining Space Requirements 5–3
Installing the Decoder 5–4
How to Connect Your Equipment 5–5
Installing and Wiring Modules 5–7
Communicating With a Host
ii
Chapter 6
Chapter Objectives 6–1
Host Port 6–1
RS–232 Interface 6–2
RS–422 Interface 6–4
RS–485 Interface 6–5
Message Format 6–7
Example Data Messages 6–9
Host Commands 6–10
Table of Contents
Host Commands Using a
RS-232 or RS-422 Interface
Chapter 7
Chapter Objectives 7–1
RS–232/RS–422 ASCII Command Protocol 7–1
Single Character Commands 7–1
Two Character Commands 7–2
Responses to Commands 7–3
Host Commands 7–4
1. Set Code 39, I 2–of–5, and Codabar Check Characters 7–5
2. Clear Output Counter 7–6
3. Enable/Disable Bar Code Type 7–6
4. Set Configuration to Default Values 7–7
5. Set Host Communications 7–7
6. Write Header Message 7–8
7. Set Package Detect Input Filter and Sense 7–9
8. Write Source Identification Message 7–10
9. Read Output Counter 7–10
10. Set Message Format 7–11
11. Read Match Code Table 7–12
12. Write Match Code Table 7–13
13. Clear No–Read Count 7–14
14. Write No–Read Message 7–15
15. Read No–Read Count 7–16
16. Set Output Condition and Duration 7–16
17. Clear Package Count 7–17
18. Read Package Count 7–17
19. Reset Decoder 7–18
20. Set Configuration to Default Values, Save to EEPROM & Restart 7–18
21. Save New Configuration to EEPROM and Restart 7–19
22. Save New Configuration to EEPROM (No Restart) 7–19
23. Set Scanner Control 7–20
24. Set Bar Code Specific Length 7–21
Host Commands Using the
RS-485 Interface
Chapter 8
Chapter Objectives 8–1
RS–485 Command Protocols 8–1
RS–485 ASCII Command Protocol 8–1
RS–485 PCCC Command Protocol 8–2
PCCC Command Format 8–2
PCCC Commands 8–5
Unprotected Read Command 8–5
Unprotected Read Command Structure 8–6
Unprotected Read Reply Format 8–7
Unprotected Read Example 8–9
iii
Table of Contents
Unprotected Write Command 8–10
Unprotected Write Command Structure 8–10
Unprotected Write Command Cont.
Unprotected Write Reply Format 8–12
Writing to the Command Area of Memory 8–13
Communication Link Diagnostic Commands 8–16
Link Diagnostic Command Structure 8–16
Diagnostic Link Reply Format 8–17
Read Diagnostic Counters Reply 8–18
Read Diagnostic Status Reply 8–19
Diagnostic Loop Reply 8–21
Reset Counters Reply 8–21
Maintenance and
Troubleshooting
Specificatuions
Setting Up the Programming
Terminal
Default Parameters Of the
Decoder
ASCII Conversion Table
Configuration Area of
Memory
Chapter 9
Chapter Objectives 9–1
Maintaining the Decoder 9–1
Power Input Fuse Replacement 9–1
Module Fuse Replacement 9–2
Troubleshooting 9–3
Chapter 10
Decoder 10–1
Appendix A A–1
Appendix B B–1
Appendix C C–1
Appendix D D–1
Protocol Selection Chart
Transmission Check Codes
iv
Appendix E E–1
Appendix F F–1
Glossary G–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index I–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table of Contents
Figures
2.1 Catalog No. 2755–DM9, –DM9E Decoder 2–3. . . . . . . . . . . . . . . . . . . .
2.2 LED Indicators 2–4. . .
2.3 Communications Ports 2–5. . .
2.4 Output Modules 2–6. . .
2.5 Input power and Scan Head Connectors 2–8. . .
3.1 Catalog No. 2755–DM9, –DM9E Decoder 3–1. . .
3.2 DC Output Module Application 3–3. . .
3.3 AC Output Module Application 3–3. . .
3.4 Input Module Auto Load Application 3–4. . .
3.5 Communications Interface Examples 3–5. . .
3.6 Decoder Memory 3–8. . .
4.1 Setup Screen #1 4–17. .
4.2 Setup Screen #2 4–28. .
4.3 Package Detect Signal 4–34. .
4.4 Internal Timer Trigger 4–35. .
4.5 Setting Inter–Scan Timer 4–39. .
4.6 Auto Load Feature 4–44. .
5.1 Mounting Dimensions of the Decoder 5–3. . .
5.2 Fasteners Used to Mount the Decoder 5–4. . .
5.3 Connecting Equipment to the Decoder’s Ports 5–5. . .
5.4 Modules and Connectors 5–7. . .
5.5 Module Connections 5–8. . .
6.1 Host Port Pin Numbers 6–2. . .
6.2 Communications With RS–232 Host Device 6–4. . .
6.3 Communications With RS–422 Host Device 6–5. . .
6.4 Communications In an RS–485 Network 6–6. . .
6.5 Message Format 6–7. . .
9.1 Power Input Fuse 9–1. . .
9.2 Output Module Fuse 9–2. . .
A.1 Connections for Cable Used With an ADM 3E Terminal A–1. . .
A.2 Connections for Cable Used With DEC–VT100 Terminal A–2. . .
A.3 One Possible Setup for DEC–VT100 Terminal A–2. . .
A.4 Connections for Cable Used With 1784–T45 Terminal A–3. . .
A.5 Connections for Cable Used With a Televideo 955 Terminal A–4. .
A.6 Connections for Cable Used With 1770–T1, –T2, or –T3 Terminals A–5
v
Chapter
Chapter Objectives
Overview of this Manual
A–B
1
Using This Manual
Read this chapter to familiarize yourself with the rest of the manual. You will learn
about:
• Contents of the manual.
• Intended audience.
• Conventions useed.
• Warnings and cautions.
This manual describes how to use the Catalog No. 2755–DM9 and DM9E
High Speed Decoders. This manual contains the following chapters:
Chapter Title Purpose
1 Using This Manual
2 Description of the Hardware
3 How the Decoder Operates
4 Configuring Your Decoder
5 Installing the Decoder
6 Communicating With a Host
7
8
9
10 Specifications
- Appendices Includes glossary of terms.
- Index Alphabetical index.
Host Commands Using the
RS-232 or RS-422 Interface
Host Commands Using the
RS–485 Interface
Maintenance and
Troubleshooting
Provides an overview of the
manual.
Describes features and
design of the decoder.
Describes how the decoder
operates.
Provides step-by-step
instructions on how to
configure the decoder.
Provides general rules and
recommendations for
installing the decoder.
Describes how a host
device can communicate
with a decoder.
Describes how to send host
commands and receive
data using the RS-232 and
RS-422 interfaces.
Describes how to send
commands and receive
data on an RS-485 Local
Area Network.
Describes basic
troubleshooting and fuse
replacement procedures.
Provides basic decoder
specifications.
1–1
Chapter 1
Using this Manual
Intended Audience
Conventions Used
You do not require any special knowledge to read this manual and follow its
instructions. If the decoder will be used to communicate with a computer or
TM
PLC
communication devices, communications standards (RS–232, RS–422,
RS–485), and communications terminology. In this manual, we describe the
commands that a host device can transmit to the decoder and the command
responses sent by the decoder. We do not describe how to create PLC or
computer programs for generating the commands.
Some chapters in this manual contain examples of how to enter data or
commands. The following conventions are used:
programmable controller, we assume you are familiar with
• A symbol or word in brackets represents a single key you would press.
These include keys such as [RETURN], [SHIFT] or [A].
• Punctuation, such as commas, and symbols such as “/” would be entered
as shown.
• ASCII codes are represented by either their mnemonic (CR, ETX, LF,
etc.) or their decimal number equivalent (CR =13, S=83, etc.). Refer to
Appendix C for a listing of the ASCII codes.
Note: When the [RETURN] key is specified, this is the carriage return
function of your keyboard. This key may also be labeled ENTER or use
some other symbol.
1–2
We have included numerous examples of CRT displays. All CRT displays
are shown inside a box with a double lined border. We have reproduced
these screens as accurately as possible. However, due to legibility and space
requirements we have modified some of the spacing.
When describing the programming terminal used to configure the decoder,
we make reference to arrow keys. If you use an Allen–Bradley Industrial
Terminal (Catalog No. 1770–T1, –T2, or –T3), you do not have arrow keys.
Use the [CTRL] and [U], [D], [L], or [R] keys for the U
ight cursor functions, respectively.
R
p, Down, Left, or
Chapter 1
Using this Manual
Warnings And Cautions
Nomenclature
Related Publications
Description Title Purpose of Publication
Catalog Number
2755-ND002②
Both warnings and cautions are found in this manual and on the equipment.
The following symbols are used:
WARNING: A warning symbol means people might be
injured if the procedures are not followed.
CAUTION: A caution symbol is used when machinery could
be damaged if the procedures are not followed.
This manual may contain some terms that you are not familiar with. We
have provided a glossary of terms at the back of this manual (Appendix G) to
assist you.
The following table lists related publications that you may require to install
and operate the decoder.
User’s Manual for Bulletin 2755 Industrial
Medium and High Speed Bar Code
Scanners.
Provides information on the Catalog Number
2755-L7 and -L9 scan heads①.
Publication 2755-829②
Publication 2755-826②
Publication 2755-801②
Publication 2760-812
Publication 2760-822
Publication 2760-823
Publication
1771-6.5.34
Publication
1771-6.5.15
Publication
1771-6.5.13
① We have provided only a partial catalog number since there are various configurations available for these scan heads.
② Additional scan heads may be available for use with the Catalog Number 2755-DM9 decoder. Refer to your Allen-Bradley representative for more information.
User’s Manual for Bulletin 2755 Enhanced
Medium Speed Scan Heads
User’s Manual for Bulletin 2755 Medium
Speed Material Handling Scanners
User’s Manual for Bulletin 2755 Modular
Bar Code Scanners
User’s Manual for Bulletin 2760–RB
Flexible Interface Module
Protocol Cartridge Programming Manual Provides instruction on using the RS-232/RS-422
Protocol Cartridge Programming Manual Provides instruction on using the RS-485
BASIC Module User’s Manual Provides information on the Catalog Number
User’s Manual for 1771–KE and 1771–KF Provides information on the Catalog Number
ASCII I/O Module User’s Manual Provides information on the Catalog Number
Provides information on the Catalog Number
2755-L4F and -L4R enhanced scan heads①.
Provides information on the Catalog Number
2755-L4F and -L4R scan heads①.
Provides information on the Catalog Number
2755-L4 and -L5 scan heads①.
Provides information on the Catalog Number
2760-RB Flexible Interface Module.
protocol cartridge for the 2760-RB module.
protocol cartridge for the 2760-RB module.
1771-DB BASIC module.
1771-KE and -KF Communications Controllers.
1771-DA ASCII I/O module.
1–3
Chapter
Chapter Objectives
Differences between Catalog
Number 2755-DM9 & 2755-DM9E
A–B
2
Description of Hardware
This chapter provides an overview of the Catalog Number 2755-DM9,
-DM9E Bar Code Decoder. We also provide descriptions of the major
features.
Note: In this chapter and in subsequent chapters, we will refer to the Catalog
Number 2755-DM9, -DM9E High Speed Decoder as the decoder.
• Catalog Number 2755-DM9 decoder includes a 120 VAC power cord, and
an English language manual. An LED label in English is attached to the
decoder.
Features
• Catalog Number 2755-DM9E decoder includes an unterminated 220 VAC
line cord and information for ordering User’s Manuals in English and
other languages. LED labels in English, French, German, Italian, and
Spanish are packaged with the decoder. Operation of the 2755-DM9 and
DM9E decoders is identical.
The decoder acquires video data from a separate laser scan head and then
decodes this data. The decoder can then:
• Send the decoded data to another device such as a host computer,
auxiliary terminal, or programmable controller.
• Compare the decoded data to previously stored data and use the results of
this comparison to operate up to eight discrete outputs (match code
operation).
Note: The decoder also maintains counters for package count, no-reads, and
discrete outputs.
The decoder is capable of decoding the following types of bar code symbols:
• Code 39. • UPC-A and E
• Interleaved 2 of 5. • EAN-8 and 13
• Codabar. • Code 128.
2–1
Chapter 2
Description of Hardware
You can program many of the operating parameters of the decoder. This
programming capability allows you to adapt the decoder to a specific
application. You can:
• Specify decoder operating modes.
• Select types and lengths of symbols to be read.
• Select communications protocols used when communicating with a
computer or programmable controller.
• Enter up to eight match codes.
• Specify up to eight discrete outputs.
• Specify up to eight discrete outputs.
You can select continuous scanning or you can define what event will trigger
the label reading process. You can specify the trigger to be:
• A signal from the package detector connected to the laser scan head.
• A command received from a host computer.
• The decoder’s internal timer.
The decoder can communicate with a host computer using the following
standards:
Laser Scan Heads
Physical Description
• RS-232.
• RS-422.
• RS-485 (Multi-drop Network using Allen-Bradley DH485 protocol).
The decoder will operate with the following scan heads:
• Catalog No. 2755-L7 and -L9 Medium and High Speed, Industrial Bar
Code Scanners.
• Catalog No. 2755-L4F, -L4R, and -L5R Medium Speed, Enhanced,
Material Handling Scanners.
Note: We have not listed complete catalog numbers for the scan heads.
These scan heads are available in a variety of configurations.
Figure 2.1 shows the decoder. The decoder is housed in a steel enclosure
(NEMA 1 rating). The decoder enclosure is 14” wide, 2.81” tall, and 10.75”
deep (refer to Chapter 5 for installation drawing). On top of the decoder are
fourteen indicator LEDs which indicate the status of the decoder and the
outputs (refer to Indicator Section in this chapter). On the back of the
decoder are the communications ports (refer to Communications Port Section
in this chapter). A separate removable cover allows for easy access to the
discrete output modules and fuses (refer to Output Module Section in this
chapter). Connectors are also provided for the laser scan head and power
line connector cables.
2–2
(Continued)
Figure 2.1
Catalog Number 2755-DM9, -DM9E
Chapter 2
Description of Hardware
Indicators
90-061-1
Fourteen LED indicators (Figure 2.2) provide an indication of the decoder
status. The indicators provide the following indications:
• POWER - This green indicator illuminates when power is applied to the
decoder.
• LASER ON - This red indicator illuminates when the decoder has enabled
the scan head to turn on the laser light source. The LED may illuminate
even if the scan head is disconnected or the “Laser On” switch for the
Catalog No. 2755-L7 or -L9 scan heads is in the OFF position.
• TRIGGER ACTIVE - This yellow indicator illuminates when the decoder
is in the triggered mode and scanning has been triggered by:
1. The package detector connected to the scan head.
2. A Start Scan command sent by the host.
3. The internal timer.
The LED remains on until a trigger OFF command is received.
• VALID READ - This green indicator illuminates momentarily whenever
the decoder has met the fields per scan and capture count parameters.
2–3
Chapter 2
Description of Hardware
Note: This LED may not correspond to a read output condition (refer to page
4-41). In the triggered mode, the read output condition must meet the fields
per package parameter.
• CPU ACTIVE - This green indicator is continuously illuminated under
normal operation. Failure of the CPU ACTIVE indicator to illuminate is
an indication of a hardware failure.
• COMMUNICATIONS - This yellow indicator illuminates momentarily
whenever data is sent to or received at either of the communications ports.
• OUTPUTS 1 through 8- Each of these red indicators indicate the status
of the output modules. When an output module is turned on, the
respective indicator illuminates.
Note: If you have a Catalog No. 2755-DM9 decoder, the LED label is
attached. If you have a Catalog No. 2755-DM9E decoder, the LED label is
not attached. Apply the appropriate language label supplied with the
decoder.
Figure 2.2
LED Indicators
2–4
90-061-5
Chapter 2
Description of Hardware
Communications Ports
There are two communication port connectors on the decoder:
• HOST port connector. The HOST port connector supports RS-232,
RS-422, and RS-485 communication interfaces. Through this port, you
can link the decoder to a host computer or programmable controller. Both
commands and data may be sent to/from the host device.
Note: The RS-485 interface allows the decoder to be installed as part of a
multi-drop network. Refer to Chapter 3 for a more detailed description.
• AUX port connector. The AUX or auxiliary port connector allows you to
program and monitor the decoder using one of the following CRTs:
Allen-Bradley Industrial Data Terminal (Catalog No. 1770-T1, -T2, and
-T3), Allen-Bradley T45 Laptop Terminal (Catalog No. 1784-T45),
Digital VT100, Televideo 955, Lear Siegler ADM 3E, or a
terminal/computer that emulates one of the terminals listed.
Figure 2.3
Communication Ports
90-061-2
2–5
Chapter 2
Description of Hardware
Output Modules
Two DC output modules (Catalog No. 1781-OB5S) are provided with the
decoder. You can add up to six more AC or DC output modules for a total of
eight. Module location #8 can also accept an input module for auto loading
match codes (refer to Chapters 3 and 4). All output module types can be
installed in any of the eight module slots. You can program the decoder to
turn on these output modules based upon the conditions you specify during
configuration of the decoder. Use these outputs to operate electromechanical
devices such as relays, alarms, etc. Fuses protect the decoder from power
overloads.
Figure 2.4
Output Modules
2–6
90-061-4
Chapter 2
Description of Hardware
The following output modules are available.
Note: Output modules function as a switch, not as a power source.
Catalog No. 1781-0B5S 1781-0A5S 1781-OM5S
Nominal Line Voltage
-- 120 VAC 240 VAC
Maximum Line Voltage
Minimum Line Voltage 3.0 VDC 12 VAC 24 VAC
Maximum Peak Off State Voltage 60 VDC
Maximum Off-State Leakage
Static off-state dv/dt -- 200 V/ usec 200 V/ usec
Maximum On-State Current
Minimum On-State Current 10 mA DC 50 mA RMS 50 mA RMS
Maximum 1 Cycle Surge -- 4.0 A Peak 4.0 A Peak
Maximum 1 Second Surge
Peak On-State Voltage 1.5 V DC
60 VDC 140 VAC 280 VAC
400 V Peak 600 V Peak
1.0 mA 2.5 mA RMS 4.0 mA RMS
0.5 A DC 0.5 A RMS 0.5 A RMS
1.5 A DC -- --
1.6 V Peak 1.6 V Peak
The following input modules are available (for position No. 8 only). See
Chapters 3 and 4.
Note: The input modules require a voltage source for activation.
Catalog No. 1781-IB5S 1781-IA5S 1781-IM5S
Maximum Input Voltage 32 VDC 140V RMS/AC 280 V RMS/AC
Minimum Input Voltage
Input Resistance 1k ohm - Maximum Input Current 32mA DC @
Drop Out Current
Allowable Off State Input Current 1.0 mA DC 3.0 mA RMS 2.0 mA RMS
Allowable Off State Input V oltage
3.3 VDC 90V RMS/AC 180 V RMS/AC
10mA RMS @
32 VDC
1.0 mA DC 2.5 mA RMS 1.5 mA RMS
2.0 VDC 50 VRMS/AC 120 VRMS/AC
140 VRMS
8mA RMS @
280 VRMS
Note: Note polarity when connecting DC Input and Output modules.
2–7
Chapter 2
Description of Hardware
Power and Scan Head Connectors
The decoder will accept line voltages from 85 to 264 volts AC at a frequency
of 47 to 63 Hz without any adjustments. The Catalog No. 2755-DM9
decoder is supplied with a 120VAC rated power cord. If you are powering a
2755-DM9 decoder with a supply voltage greater than 120 VAC, you must
obtain a suitable power cord.
Note: Catalog No. 2755-DM9E is supplied with an unterminated power cord.
Attach a suitable connector using the diagram provided in Chapter 5.
A 15 pin D connector is provided on the decoder for connecting the laser
scan head. You can connect the decoder to the scan head using one of the
following:
• For Catalog No. 2755-L7 and -L9 scan heads use-
10 foot (3.05 meter) cable (Catalog No. 2755-CL10)
25 foot (7.62 meter) cable (Catalog No. 2755-CL25)
• For Catalog No. 2755-L4 and -L5 scan heads use-
10 foot (3.05 meter) cable (Catalog No. 2755-CK10)
25 foot (7.62 meter) cable (Catalog No. 2755-CK25)
Note: The scan head is powered by the decoder through the cable. The scan
heads do not require a separate power source.
Figure 2.5
Input Power and Scan Head Connectors
90-061-4
2–8
Chapter 2
Description of Hardware
Accessories
The following table lists the accessories that you may require for use with the
decoder.
Catalog Number Item Description
Raster and side scanning devices that operate at 350 scans per
second. Raster scanners scan both vertical and horizontal directions
2755-L7①
2755-L9①
2755-L4F①
-L4R①
2755-L5R①
1781-OB5S DC Output Module 3 to 60 VDC output at 0.5 amperes.
1781-OA5S AC Output Module 12 to 140 VAC output at 0.5 amperes.
1781-OM5S AC Output Module 24 to 280 VAC output at 0.5 amperes.
1781-IB5S DC Input Module 3.3 to 32 VDC
1781-IA5S AC Input Module 90 to 140 VRMS/VDC
1781-IM5S AC Input Module 180 to 280 VRMS/VDC
2760-A485 RS-485 Connector Use these connectors to create cables for an RS-485 network.
2755-CL10 10-ft (3.05 meters) Scan Head Cable
2755-CL25 25-ft (7.62 meters) Scan Head Cable
2755-CK10 10-ft (3.05 meters) Scan Head Cable
2755-CK25 25-ft (7.62 meters) Scan Head Cable
W77104-899-01
Purchased
Locally
Package
Detector
Assembly
User Created Host Port Communications Cable For connecting host device to the decoder, refer to Chapter 6.
User Created Auxiliary Port Communications Cable
W77121-801-01
W77121-801-02
Industrial Medium Speed Bar Code
Scanner
Industrial High Speed Bar Code Scanner
Enhanced Medium Speed Scanner
Enhanced Medium Speed Raster Scanner
Replacement Fuse- Power Output
Modules
Replacement Fuse- Line Input Power 250V ( 1 amp, slow blow), 5 x 20 mm or 3AG
2755-NP3
2755-NP5
2755-NP1
2755-NP4
Power Cords -
120 V AC
220 V AC- Unterminated one end
simultaneously. Some of these scan heads have a maximum read
distance of 50” (1.27 meters) depending upon symbol size and
quality. Scanners can read Case Code symbols (symbols directly
printed on kraft paper/cardboard boxes).
Raster and side scanning devices that operate at 800 scans per
second. Raster scanners scan both vertical and horizontal directions
simultaneously. Some of these scan heads have a maximum read
distance of 30”
(76 cm) depending upon symbol size and quality .
Front or side scanners that operate at 200 scans per second. Some
of these scan heads have a maximum read distance of 50” (1.27
meter) depending upon symbol size and quality . Scanners can read
Case Code symbols (symbols directly printed on kraft
paper/cardboard boxes).
Raster scanners that operate at 200 scans per second. This scan
head has a maximum read distance of 45” (1.14 meters) depending
upon symbol size and quality . Scan head scans both vertical and
horizontal directions simultaneously. Scanner can read Case Code
symbols (symbols directly printed on kraft paper/cardboard boxes).
Use to connect decoder to Catalog No. 2755-L7 or -L9 scan head.①
Use to connect decoder to Catalog No. 2755-L7 or -L9 scan head.①
Use to connect decoder to Catalog No. 2755-L4 or -L5 scan head.①
Use to connect decoder to Catalog No. 2755-L4 or -L5 scan head.①
Plug-in type fuses provide overload protection for the decoder.
Optional, for 2755-L7, -L9 Scan Heads
Optional, for 2755-L7, -L9 Scan Heads
Optional, for 2755-L4, -L5 Scan Heads
Optional, for 2755-L4, -L5 Scan Heads
For connecting programming terminal to the decoder. Refer to
Appendix A.
Replacement power cord.
User must provide suitable connector.
① We have not provided the complete catalog number since these heads are available in a variety of configurations.
2–9
Chapter
Chapter Objectives
How the Decoder Operates
A–B
3
How the Decoder Operates
This chapter provides a brief description of how the decoder operates. We
also provide a brief description of how the decoder communicates with host
devices.
Figure 3.1 is a block diagram of the decoder.
Figure 3.1
Catalog Number 2755-DM9 Decoder
DECODER
DATA
ACQUISITION
POWER SUPPLY - An internal power supply provides power for both the
laser scan head and internal circuitry of the decoder. As stated earlier, the
source voltage may range from 85 to 264 volts AC. The power supply will
automatically adjust to the input voltage.
MICROPROCESSOR
POWER
SUPPLY
I/O
LASER SCAN HEAD
DATA ACQUISITION CIRCUIT - The data acquisition circuitry of the
decoder receives both video and synchronization signals from the laser scan
head. The data acquisition circuitry filters and stores blocks of data received
from the scan head in the Random Access Memory (RAM) of the decoder.
3–1
Chapter 3
How the Decoder Operates
MICROPROCESSOR - The microprocessor reads the information obtained
by the data acquisition circuit, processes the information, and then makes
decisions on what to do with the decoded data based upon your programming
instructions.
I/O - A single 25 pin connector (HOST PORT) provides three different
interfaces (RS-232, RS-422, and RS-485) for communications with a host
computer or programmable controller. The I/O section of the decoder
supports asynchronous data transmission at baud rates of up to 38,400 bits
per second.
Another 25 pin connector (AUX PORT) provides an RS-232 interface for
programming and monitoring of the decoder using a programming terminal.
Refer to Chapter 2 for a listing of the terminals that can be used for
programming or monitoring.
Up to eight modules can be plugged into the circuit board of the decoder.
Refer to Chapter 2 for a description of the input and output modules that can
be used. Output modules function as switches, not as power sources (refer to
Figures 3.2 and 3.3).
Note: Outputs are initially turned off (open) when power is first applied to
the decoder and when the decoder is turned off.
DC Output Module Application
Figure 3.2 illustrates a typical DC output module application. When using
high impedance loads, you may have to add an additional resistor (Rx) in
parallel with the load. Select a value for Rx that maintains a minimum
current of 10 mA through the output module in the on state. Typical values
for Rx range from 300 to 6,000 ohms depending upon the source voltage.
Figure 3.2
DC Output Module Application
DECODER
DC SOURCE 3-60 VDC
+
_
LOAD
_
+
DC OUTPUT MODULE
CONNECTOR BLOCK
FUSE
3–2
Rx
Chapter 3
How the Decoder Operates
AC Output Module Application
Figure 3.3 illustrates a typical AC output module application. When using
high impedance loads, you may have to add an additional resistor (Rx) in
parallel with the load. Select a value for Rx that maintains a minimum
current of 50 mA RMS through the output module in the on state.
Figure 3.3
AC Output Module Application
DECODER
AC SOURCE
LOAD
Rx
AC OUTPUT MODULE
CONNECTOR BLOCK
FUSE
Input Module Auto Load Application
Figure 3.4 illustrates the auto load input module application.
Figure 3.4
Typical Input Module Auto Load Application
DECODER
Auto Load
CONNECTOR BLOCK
INPUT MODULE
AC or DC
MODULE LOCATION #8 ONLY
FUSE
Pushbutton
+
-
Communications
AC or DC SOURCE
As stated earlier the decoder can transmit decoded bar code information to a
host computer or programmable controller. The three communications
3–3
Chapter 3
How the Decoder Operates
interfaces (RS-232, RS-422, and RS-485) provide a variety of ways to
accomplish communications with a host. Figure 3.5 illustrates some of the
possible host interfaces.
Note: You can also use the decoder as a stand-alone device using the discrete
outputs for control.
Figure 3.5
Communications Interface Examples
PLC
1771 I/O Rack
2760-RB
2760-SFC2
2755-DM9
2755-DM9
Decoder
2755-DM9
Decoder
Decoder
1
1
1
PLC TO DECODER USING
A FLEXIBLE INTERFACE
MODULE (RS-485)
2755-DM9
Decoder
2
2755-DM9
Decoder
2
2755-DM9
Decoder
2
PLC
PLC TO DECODER USING A
FLEXIBLE INTERFACE
MODULE (RS-232, RS-422)
• • • • • •
• • • • • •
• • • • • •
2755-DM9
Decoder
31
2755-DM9
Decoder
31
2755-DM9
Decoder
31
3–4
2755-DM9
Decoder
2755-DM9
Decoder
1771 I/O Rack
2760-RB
2760-SFC1
RS-232 or RS-422
2755-DM9
Decoder
Catalog No. 2760-RB is a Flexible Interface
Catalog No. 2760-SFC1, -SFC2 are Protocol Cartridges
Chapter 3
How the Decoder Operates
Figure 3.5
Communications Interface Examples (Continued)
PLC TO DECODER USING
AN ASCII MODULE
PLC
1771 I/O Rack
1771-DA
RS-232
2755-DM9
Decoder
COMPUTER TO
DECODER
Host Computer
RS-232 or RS-422
2755-DM9
Decoder
PLC TO DECODER USING A
BASIC MODULE
PLC
1771 I/O Rack
1771-DB
RS-232
2755-DM9
Decoder
Catalog No. 1771-DB is a BASIC I/O Module
Catalog No. 1771-DA is an ASCII I/O Module
ALLEN-BRADLEY LOCAL-AREA NETWORK - Using the Catalog No.
2760-RB Flexible Interface Module with the 2760-SFC2 protocol cartridge
and the DM9 in the RS-485 mode, you can multi-drop up to 31 devices on
each port of the 2760-RB module.
PROGRAMMABLE CONTROLLERS - You can connect the decoder to a
programmable logic controller in one of three ways:
• Through the Allen-Bradley Data Highway.
• Through a Flexible Interface Module (Catalog No. 2760-RB). This
module can be used to create an RS-485 Local Area Network or
point-to-point communications using the RS-232 or RS-422
communications interfaces.
• Directly, using a Catalog No. 1771-DB BASIC module or 1771-DA
ASCII I/O module.
HOST COMPUTERS- In most cases, you can directly connect your host
computer to the decoder using the RS-232 or RS-422 interface. The decoder
can also communicate with an industrial computer through the Allen-Bradley
Data Highway.
3–5
Chapter 3
How the Decoder Operates
RAM and EEPROM Memory
Before you try to change the operating configuration of the decoder, you
should understand how configuration parameters are stored. The decoder has
two types of memory:
• EEPROM- Electrically Erasable Programmable Read Only Memory
contains the “non-volatile” operating configuration of the decoder. The
term “non-volatile” means that the memory is not lost when you turn the
power off or restart the decoder.
• RAM- Random Access Memory contains the current operating
configuration of the decoder. Any changes made to the the operating
configuration of the decoder are made to the decoder’s RAM. All
information stored in the RAM is erased when the power to the decoder is
turned off. When the decoder is turned back on (rebooted), the
configuration parameters are copied from non-volatile memory
(EEPROM) to the RAM.
Figure 3.6 illustrates the relationship between the RAM and EEPROM
memory. Notice that the user interface is with the RAM memory. Also,
notice that the decoder transfers the contents of the RAM to the EEPROM
during a SAVE operation and copies the same contents from the EEPROM to
RAM during startup.
Note: The configuration in RAM determines the decoder performance
(operating characteristics).
Figure 3.6
Decoder Memory
3–6
Decoder
Performance
User Interface
RECALL
START-UP
RESTART
RAM
EEPROM
SAVE
DEFAULT
Default
Configuration
Settings
-Programmer
-Host
When you change the operating configuration of the decoder, you are
changing the configuration stored in the decoder’s RAM. Since the decoder
takes its current operating instructions from RAM, any changes you make
Chapter 3
How the Decoder Operates
will become effective immediately (except for host communications
parameters listed below). If you want to enter changes into the decoder’s
permanent memory (EEPROM), you must use the SAVE command. When
the decoder is restarted, the operating parameters of the EEPROM are
transferred into RAM. If you don’t transfer the contents of the RAM to the
EEPROM (SAVE function), any changes made to the operating configuration
stored in RAM will be erased when the power is turned off.
Note: Unlike the other decoder operating parameters, changes to the
following parameters will not take effect until you SAVE the changes and
then restart the decoder.
• HOST PROTOCOL
• DEVICE ADDRESS
• ACK and NAK CHARACTERS①
Operating Modes
• BAUD RATE
• NUMBER OF DATA & STOP BITS
• PARITY
① Changes to ACK NAK characters will take effect immediately if you are in the ACK/NAK mode.
The decoder also stores the original factory set operating parameters in
EPROM. This type of memory cannot be changed by the user, and is always
available in case of a programming error. When you use a DEFAULT
command (described in next chapter), the decoder transfers the factory set
default parameters to the RAM. Once installed in RAM, the default
parameters control the operation of the decoder. If you want to save the
default parameters into the EEPROM, you must use the SAVE command.
A RECALL command (described in next chapter) transfers the previously
SAVED configuration from the EEPROM to the decoder’s RAM. Once
installed into RAM, the recalled configuration is displayed and controls
operation of the decoder.
When you configure the operation of the decoder, you will be required to
provide a variety of operating parameters. You should have an understanding
of the decoder’s operating modes prior to configuring the decoder (Chapter
4). The decoder operates in one of two modes:
• Continuous mode - In this mode, the decoder will continuously attempt to
decode data. Use this mode for initial scan head adjustments and
positioning.
• Triggered mode - In this mode, the decoder will only attempt to decode
data after receiving a trigger.
3–7
Chapter 3
How the Decoder Operates
In the triggered mode of operation, there are three possible trigger sources:
• Host command - The command is generated by a host computer or
programmable controller.
• Package detect - A package detector connected to the scan head is the
source for the trigger.
• Internal timer - The internal timer cycles the trigger from on to off based
on a timed interval.
Trigger Ending Coditions
Response Modes
When a trigger on is received, the decoder will continuously attempt to
decode bar codes until one of the following trigger ending conditions occurs:
(a) The number of fields (bar codes) per package count is satisfied.
(b) A trigger off command is sent by a host device.
(c) Package detect signal is no longer present.
(d) The internal timer (No-Read timer) times out.
In the triggered mode of operation there are two options which determine
when the decoder will send bar code information to a host and/or operate
discrete outputs:
• After Valid Package - A valid package is a package that has valid bar
code symbols and meets the fields (bar codes) per package count
(condition
(a) listed above).
• End of Trigger - Refer to trigger ending conditions (b, c, d) listed above.
3–8
Chapter
Chapter Objectives
Initial Programming of the Decoder
A–B
4
Configuring Your Decoder
Because the decoder can be used many ways, you will need to configure the
decoder to meet the requirements of your application. To do this, you must
make some decisions. We will show you how to use the menus and setup
screens that appear on a programming terminal to select the options you
need.
You must configure the decoder to meet the requirements of the application.
You can configure the decoder either before or after installation. If you
change the configuration while a triggered decode is in progress, there is
the possibility of missing a package and/or losing data.
Note: The default parameters for the decoder are given in Appendix B. If
these settings meet your requirements, you will not have to program the
decoder.
You will need the following equipment:
1. Decoder with power cable.
2. One of the following programming terminals:
• Allen-Bradley Industrial Terminal (Catalog No.1770-T1, -T2, or -T3).
• Allen-Bradley T45 Laptop Terminal (Catalog No. 1784-T45).
• Lear Siegler 3E.
• Televideo 955.
• DEC VT-100.
• A terminal or personal computer that accurately emulates one of the
above.
3. A cable to connect your programming terminal to the decoder.
Note: Prior to configuring your decoder, we suggest that you review the
description of how the decoder stores configuration data (refer to Chapter 3,
RAM and EEPROM Memory descriptions).
Note: Refer to Appendix A for programming terminal setup. The
programming terminal you use must be configured with the following
parameters:
Number of data bits: 8
Number of stop bits: 1
Baud rate: 9600
Parity: None
Flow Control: XON / XOFF
4–1
Chapter 4
Configuring Y our Decoder
Programming Terminal Cable
Menus and Setup Screens
Programming of the decoder is done through the AUX connector on the back
of the decoder.
female, D type connector. Depending upon your programming terminal,
most standard RS-232 communications cables will work. If you need to
create a communications cable, refer to Appendix A.
You can program and/or monitor the operation of the decoder using the
following CRT screens:
The AUX port connector on the decoder is a standard 25 pin,
• Select Language Screen - Use this screen to select English, French,
German, Italian, or Spanish language screens.
• CRT Select Menu - You use this menu to select the type of programming
terminal being used.
• Select operation Menu - Using this menu, you select one of six
operations:
1) Display Labels Screen- Displays bar code labels as they are decoded.
2) System Status Screen- Displays the status of the decoder.
3) Setup Screens Setup Screen 1- Use this screen to configure the host interface which
includes host message format, host communications parameters and
protocol, and filtering of the package detect input.
Start-up Procedure
4–2
Setup Screen 2- Use this screen to configure the decoder for the bar
code symbologies, bar code lengths, scan head operation, match code
settings, and configuration of output modules.
4) Reset Status and Counters
5) Restart System
6) Select Language Screen- This screen allows you to reselect one of the
following languages:
• English
• French
• German
• Italian
• Spanish
After you have connected the programming terminal to the decoder and
attached the power cord:
Step 1 - Turn ON the programming terminal and configure the terminal for
communications with the decoder. Appendix A provides information on
setting up the programming terminal.
Chapter 4
Configuring Y our Decoder
Step 2 - Turn the decoder ON. The green LEDs, labeled POWER ON and
CPU ACTIVE, will light.
Step 3 - When the following screen appears, press the key that corresponds
to the language you are using. All of the remaining screens will appear in the
selected language.
SELECT LANGUAGE CHOIX DU LANGAGE WAEHLE SPRACHE
1) English 1) Anglais 1) Englisch
2) French 2) Francais 2) Franzoesisch
3) German 3) Allemand 3) Deutsch
4) Italian 4) Italien 4) Italienisch
5) Spanish 5) Espagnol 5) Spanisch
Press 1, 2, 3, 4, 5, or ESC Appuyer 1, 2, 3, 4, 5 ou ESC Drueck
e 1, 2, 3, 4, 5, oder ESC
SELEZIONARE LINGUA SELECCIONAR LENGUA
1) Inglese 1) Ingles
2) Francese 2) Frances
3) Tedesco 3) Aleman
4) Italiano 4) Italiano
5) Spangnolo 5) Castellano
Premere 1, 2, 3, 4, 5 o ESC Pulsar 1, 2, 3, 4, 5, o ESC
Step 4 - After selecting the language, the decoder will display the CRT select
screen. Press the key (1, 2, 3, 4, or 5) that corresponds to the terminal you
are using. Pressing the [ESC] key, will return you to the language selection
screen.
2755-DM9 Bar Code Reader VX.XX
Copyright 1990 Allen-Bradley Company, Inc.
SELECT CRT TYPE
1 - Allen-Bradley 1770 Industrial Terminal
2 - Allen-Bradley T45 Portable Terminal
3 - Lear Siegler ADM 3E
4 - Televideo 955
5 - Digital VT100
Press 1, 2, 3, 4, 5 or ESC
Step 5 - After selecting the CRT type, the decoder will display the select
operation menu. The remaining displays that you will see depends upon the
operation that you select.
4–3