Allen-Bradley 1756-L5 Owner's manual

Programming Manual
Logix5000 Controllers Messages
Catalog Numbers 1756-L1, 1756-L55, 1756-L61, 1756-L62, 1756-L63, 1769-L31, 1769-L32C, 1769-L32E, 1769-L35CR, 1769-L35E,
1789-L60, 1794-L34, PowerFlex 700S/SE

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 available from
your local Rockwell Automation sales office or online at http://www.rockwellautomation.com/literature/) 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 Rockwell Automation, Inc. 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, Rockwell Automation, Inc. cannot assume responsibility or
liability for actual use based on the examples and diagrams.
No patent liability is assumed by Rockwell Automation, Inc. 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 Rockwell Automation,
Inc., is prohibited.
Throughout this manual, when necessary, we use notes to make you aware of safety considerations.
Allen-Bradley, Rockwell Automation, Logix5000, RSLogix 5000, ControlLogix, GuardLogix, CompactLogix, PowerFlex, SoftLogix, Rockwell Software, PLC-2, PLC-3, PLC-5, SLC, SLC 500, and TechConnect are
trademarks of Rockwell Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.
WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous environment, which may
lead to personal injury or death, property damage, or economic loss.
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 a hazard, and recognize the consequence
SHOCK HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous voltage may be
present.
BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may reach
dangerous temperatures.
IMPORTANT Identifies information that is critical for successful application and understanding of the product.

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 3
Summary of Changes
This manual contains new and updated information. Changes throughout this
revision are marked by change bars, as shown to the right of this paragraph.
New and Updated Information
This table contains the changes made to this revision.
Topic Page
Added information on the Large Connection checkbox to second footnote under
table.
11
Added a new row to the table that discusses “If the MSG instructions are to” —
New row starts with “Same device and cached and large connection”.
12
Added additional information to the example given for Share a Connection. 12
Changed Destination to Destination Element to reflect changes to the UI. 14
Updated instructions on setting the path to a remote controller. 27
Updated the screen shot to reflect changes to the UI. 30
Changed Destination Tag to Destination Element and Source Tag to Source
Element to reflect changes to the UI.
30

4 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Summary of Changes
Notes:

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 5
Table of Contents
Summary of Changes New and Updated Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Table of Contents
Preface
Purpose of This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 1
Controller Messages
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Supported Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Message Queue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Cache List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Unconnected Buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Get or Set the Number of Unconnected Buffers. . . . . . . . . . . . . . . . . . . . . 13
Get the Number of Unconnected Buffers . . . . . . . . . . . . . . . . . . . . . . . 14
Set the Number of Unconnected Buffers . . . . . . . . . . . . . . . . . . . . . . . 14
Convert Between INTs and DINTs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Chapter 2
Manage Multiple Messages
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Message Manager Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Initialize the Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Restart the Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Send the First Group of MSGs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Enable the Second Group of MSGs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Send the Second Group of MSGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Enable the Next Group of MSGs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Send the Next Group of MSGs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Chapter 3
Send a Message to Multiple
Controllers
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Set Up the I/O Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Define Your Source and Destination Elements. . . . . . . . . . . . . . . . . . . . . . 24
Create the MESSAGE_ CONFIGURATION Data Type. . . . . . . . . . . 25
Create the Configuration Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Get the Size of the Local Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Load the Message Properties for a Controller . . . . . . . . . . . . . . . . . . . . . . . 29
Configure the Message. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Step to the Next Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Restart the Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Index

6 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Table of Contents
Notes:

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 7
Preface
Purpose of This Manual
This manual shows how to program message (MSG) instructions to and from
Logix5000 controllers. This manual is one of a set of related manuals that show
common procedures for programming and operating Logix5000 controllers.
For a complete list of common procedures manuals, see the
Logix5000 Controllers Common Procedures Programming Manual, publication
1756-PM001.
The term Logix5000 controller refers to any controller that is based on the
Logix5000 operating system, such as:
•CompactLogix controllers.
•ControlLogix controllers.
•DriveLogix controllers.
•FlexLogix controllers.
•SoftLogix5800 controllers.
Additional Resources
These documents contain additional information concerning related products
from Rockwell Automation.
You can view or download publications at http://www.rockwellautomation.com/
literature/. To order paper copies of technical documentation, contact your local
Allen-Bradley distributor or Rockwell Automation sales representative.
Resource Description
Industrial Automation Wiring and Grounding Guidelines,
publication 1770-4.1
Provides general guidelines for installing a Rockwell
Automation industrial system.
Product Certifications website, http://www.ab.com Provides declarations of conformity, certificates, and
other certification details.

8 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Preface
Notes:

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 9
Chapter 1
Controller Messages
Introduction This section describes how to transfer data between controllers (send or receive
data) by executing a message (MSG) instruction. Cache connections and buffers
are explained so you can correctly program the controller.
Supported Data Types
The following data types are supported when sending CIP messages:
•SINT
•INT
•DINT
•LINT
•REAL
In addition, any structure type that is predefined, module-defined, or user-
defined can be used for sending a message.
See page 16 for more information on INTs and DINTs.
For complete details on programming a message instruction, see the Logix5000
Controllers General Instruction Reference Manual,
publication 1756-RM003.
EXAMPLE Execute a Message (MSG) Instruction
If count_send = 1 and count_msg.EN = 0 (MSG instruction is not already enabled), then execute a MSG instruction that sends data to another controller.
count_send
/
count_msg.en
EN
DN
ER
Type - Unconfigured
Message Controlcount_msg ...
MSG

10 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Chapter 1 Controller Messages
This diagram shows how the controller processes MSG instructions.
Message Queue
The message queue holds up to 48 MSG instructions, including those that you
configure as a block-transfer read or block-transfer write. When the queue is full,
an instruction tries to enter the queue on each subsequent scan of the instruction,
as shown below.
Description
The controller scans the MSG instruction and its rung-condition-in goes true. The message will pass to a throttle, which has 16 positions. If the throttle is full, the message
will stay enabled but is held until another controller scan.
The System-overhead time slice executes and the message is pulled from the throttle to the message queue.
If the MSG instruction Then the MSG instruction
Does not use a connection or the connection was not previously cached.
Uses a connection and the connection is cached
Uses an unconnected buffer to establish communication with the
destination device.
Does not use an unconnected buffer.
Communication occurs with the destination device.
Message Queue
Yes
Unconnected Outgoing
Buffers (10 to 40)
No
Destination Device
Cached?
48
total
1 2
4
3
Cache List
MSG
Throttle
16
1
2
3
4
Rung-condition-in false true false
.EN bit off on
.EW bit off on
1 2 3 4

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 11
Controller Messages Chapter 1
Cache List
Depending on how you configure a MSG instruction, it may use a connection to
send or receive data.
If a MSG instruction uses a connection, you have the option to leave the
connection open (cache) or close the connection when the message is done
transmitting.
Description
The controller scans the MSG instruction.
The rung-condition-in for the MSG instruction is true.
The EN bit is set.
The MSG instruction attempts to enter the queue but there are 16 throttle positions. If all 16 are filled and a 17th message is executed, the message
goes enabled, but ...
...the EW bit remains cleared.
& The controller scans the MSG instruction.
The rung-condition-in for the MSG instruction is false.
The EN bit remains set.
The MSG instruction attempts to pass through the throttle, but there are no open positions yet.
The EW bit remains cleared.
The controller scans the MSG instruction.
The MSG instruction attempts to enter the queue. This time the throttle position is open and the message can pass to the message queue.
The EW bit is set.
1
2 3
4
This type of message And this communication method Uses a connection
CIP data table read or write Your option(1)
PLC-2, PLC-3, PLC-5, or SLC (all types) CIP
CIP with Source ID
No
DH+ Yes
CIP generic Your option(2)
Block-transfer read or write Yes
(1) CIP data table read or write messages can be connected or unconnected. But, for most applications, we recommend you leave CIP data table read or write
messages connected.
(2) CIP generic messages can be connected or unconnected. But for most applications, we recommend you leave CIP generic messages unconnected, unless you want
to use the Large Connection option.
If you Then
Cache the connection The connection stays open after the MSG instruction is done. This optimizes
execution time. Opening a connection each time the message executes increases
execution time.
Do not cache the connection The connection closes after the MSG instruction is done. This frees up that
connection for other uses.

12 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Chapter 1 Controller Messages
The controller has these limits on the number of connections that you can cache:
If several messages go to the same device, the messages may be able to share a
connection.
Unconnected Buffers
To establish a connection or process unconnected messages, the controller uses an
unconnected buffer.
If you have this software and
firmware revision
Then you can cache
11.x or earlier •Block transfer messages for up to 16 connections
•Other types of messages for up to 16 connections
12.xor later Up to 32 connections
If the MSG instructions are to And they are Then
Different devices Each MSG instruction uses 1 connection.
Same device and cached and not large connection Enabled at the same time (same scan) Each MSG instruction uses 1 connection and 1 cached
buffer.
Not enabled at the same time All MSG instructionsuse1connection and 1 cachedbuffer.
They share the connection and the buffer.
Same device and cached and large connection Enabled at the same time (same scan) Each MSG instruction uses 1 connection and 1 cached
buffer.
Not enabled at the same time All MSG instructionsuse1connection and 1 cachedbuffer.
They share the connection and the buffer.
EXAMPLE Share a Connection.
•If the controller alternates between sending a block-transfer read message and a block-transfer write
message to the same module, then together both messages count as one connection. Caching both
messages counts as one on the cached buffer.
•If the controller sends 10 cached connected messages to the same bridge module (e.g. 1756-EN2T)
where 7 utilize a standard connection (large connection unchecked) and 3 utilize a large connection,
then the 7 standard connection messages all utilize one cached connection. The 3 large connection
messages all utilize another cached connection. In total, the 10 messages utilize 2 separate cached
connections.
Term Definition
Unconnected buffer An allocation of memory that the controller uses to process unconnected communication. The controller performs
unconnected communication when it:
• establishes a connection with a device, including an I/O module.
• executes a MSG instruction that does not use a connection.
The controller can have 10… 40 unconnected buffers.
• The default number is 10.
• To increase the number of unconnected buffers, execute a MSG instruction that reconfigures the number of
unconnected buffers.
• Each unconnected buffer uses 1.2 KB of memory.
• If all the unconnected buffers are in use when an instruction leaves the message queue, the instruction errors and
data does not transfer.

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 13
Controller Messages Chapter 1
If a MSG instruction uses a connection, the instruction uses an unconnected
buffer when it first executes to establish a connection. If you configure the
instruction to cache the connection, it no longer requires an unconnected buffer
once the connection is established.
Guidelines
As you plan and program your MSG instructions, follow these guidelines.
Get or Set the Number of
Unconnected Buffers
To determine or change the number of unconnected buffers, use a MSG
instruction.
•The range is 10…40 unconnected buffers.
•The default number is 10.
•Each unconnected buffers uses 1.1 KB of memory.
Guideline Details
1. For each MSG instruction, create a control tag. Each MSG instruction requires its own control tag.
• Data type = MESSAGE
• Scope = controller
• The tag cannot be part of an array or a user-defined data type.
2. Keep the source and/or destination data at the controller
scope.
A MSG instruction can access only tags that are in the Controller Tags folder (controller scope).
3. If your MSG is to a device that uses 16-bit integers, use a
buffer of INTs in the MSG and DINTs throughout the project.
If your message is to a device that uses 16-bit integers, such as a PLC-5 or SLC 500 controller, and it transfers integers
(not REALs), use a buffer of INTs in the message and DINTs throughout the project.
This increases the efficiency of your project because Logix5000 controllers execute more efficiently and use less
memory when working with 32-bit integers (DINTs).
See page 16.
4. Cache the connected MSGs that execute most frequently. Cache the connection for those MSG instructions that execute most frequently, up to the maximum number
permissible for your controller revision.
This optimizes execution time because the controller does not have to open a connection each time the message
executes.
5. If you want to enable more than 16 MSGs at one time, use
some type of management strategy.
If you enable more than 16 MSGs at one time, some MSG instructions may experience delays in entering the queue.
To guarantee the execution of each message, use one of these options:
• Enable each message in sequence.
• Enable the messages in groups.
• Program a message to communicate with multiple devices.
• Program logic to coordinate the execution of messages.
6. Keep the number of unconnected and uncached MSGs less
than the number of unconnected buffers.
The controller can have 10…40 unconnected buffers. The default number is 10.
• If all the unconnected buffers are in use when an instruction leaves the message queue, the instruction errors
and does not transfer the data.
• You can increase the number of unconnected buffers (40 max), but continue to follow guideline 5.
• To increase the number of unconnected buffers, see page 13.

14 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Chapter 1 Controller Messages
Get the Number of Unconnected Buffers
To determine the number of unconnected buffers that the controller currently
has available, configure a Message (MSG) instruction as follows.
Set the Number of Unconnected Buffers
As a starting value, set the number of unconnected buffers equal to the number of
unconnected and uncached messages enabled at one time plus approximately 5.
The additional 5 buffers provide a cushion in case you underestimate the number
of messages that are enabled at one time.
On this tab For this item Type or select
Configuration Message Type CIP Generic
Service Type Custom
Service Code 3
Class 304
Instance 1
Attribute 0
Source Element source_array where data type = SINT[4]
In this element Enter
source_array[0] 1
source_array[1] 0
source_array[2] 17
source_array[3] 0
Source Length (bytes) 4 (Write 4 SINTs.)
Destination Element destination_array where data type = SINT[10] (Leave all the values = 0.)
destination_array[6] = current number of unconnected buffers
Communication Path 1, slot_number_of_controller

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 15
Controller Messages Chapter 1
To change the number of unconnected buffers of the controller, configure a
Message (MSG) instruction as follows.
On this tab For this item Type or select
Configuration Message Type CIP Generic
Service Type Custom
Service Code 4
Class 304
Instance 1
Attribute 0
Source Element source_array where data type = SINT[8]
In this element Enter
source_array[0] 1
source_array[1] 0
source_array[2] 17
source_array[3] 0
source_array[4] Number of unconnected buffers that you want.
source_array[5] 0
source_array[6] 0
source_array[7] 0
Source Length (bytes) 8 (Write 8 SINTs.)
Destination Element destination_array where data type = SINT[6] (Leave all the values = 0.)
Communication Path 1, slot_number_of_controller

16 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Chapter 1 Controller Messages
Convert Between INTs
and DINTs
In the Logix5000 controller, use the DINT data type for integers whenever
possible. Logix5000 controllers execute more efficiently and use less memory
when working with 32-bit integers (DINTs).
If your message is to a device that uses 16-bit integers, such as a PLC-5 or
SLC 500 controller, and it transfers integers (not REALs), use a buffer of INTs in
EXAMPLE Set the Number of Unconnected Buffers
If S:FS = 1 (first scan), then set the number of unconnected buffers for the controller.
Source_Array[0] = 1
Source_Array[1] = 0
Source_Array[2] = 17
Source_Array[3] = 0
Source_Array[4] = 12 (The number of unconnected buffers that you want. In this example, we want 12 buffers.)
If UCB_Set.EN = 0 (MSG instruction is not already enabled) then
MSG instruction sets the number of unconnected buffers = Source_Array[4].
Tag Name Type Description
UCB_Set MESSAGE Control tag for the MSG instruction.
Source_Array SINT[8] Source values for the MSG instruction, including the number of unconnected buffers that you want.

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 17
Controller Messages Chapter 1
the message and DINTs throughout the project. This increases the efficiency of
your project.
1. The Message (MSG) instruction reads 16-bit integers (INTs) from the
device and stores them in a temporary array of INTs.
2. An File Arith/Logical (FAL) instruction converts the INTs to DINTs for
use by other instructions in your project.
1. An FAL instruction converts the DINTs from the Logix5000 controller to
INTs.
2. The MSG instruction writes the INTs from the temporary array to the
device.
Read 16-Bit Integers Data from the
device
Buffer of INTs DINTs for use in the
project
Word 1 INT_Buffer[0] DINT_Array[0]
Word 2 INT_Buffer[1] DINT_Array[1]
Word 3 INT_Buffer[2] DINT_Array[2]
12
Write 16-Bit Integers DINTs from the project Buffer of INTs Data for the
device
DINT_Array[0] INT_Buffer[0] Word 1
DINT_Array[1] INT_Buffer[1] Word 2
DINT_Array[2] INT_Buffer[2] Word 3
12
EXAMPLE Read integer values from a PLC-5 controller
If Condition_1 = 1 And Msg_1.EN = 0 (MSG instruction is not already enabled) then
read 3 integers from the PLC-5 controller and store them in INT_Buffer (3 INTs).
If Msg_1.DN =1 (MSG instruction has read the data.) then
reset the FAL instruction.

18 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Chapter 1 Controller Messages
The FAL instruction sets DINT_Array = INT_Buffer. This converts the values to 32-bit integers (DINTs).
EXAMPLE Write integer values to a PLC-5 controller.
If Condition_2 = 1 then
reset the FAL instruction.
The FAL instruction sets INT_Buffer = DINT_Array. This converts the values to 16-bit integers (INTs).
If Control_2.DN = 1 (FAL instruction has converted the DINTs to INTs)
and Msg_2.EN = 0 (MSG instruction is not already enabled) then
write the integers in INT_Buffer (3 INTs) to the PLC-5 controller.

Rockwell Automation Publication 1756-PM012D-EN-P - November 2011 19
Chapter 2
Manage Multiple Messages
Introduction
You can use ladder logic to send groups of message (MSG) instructions in
sequence.
•To be processed, each MSG instruction must enter the message queue.
•The queue holds 48 MSGs.
•If more than 16 MSGs are enabled at one time, the message throttle will
prevent some of the messages from being able to be placed into the message
queue.
•If this occurs, the MSG has to wait until there is room on the queue before
the controller can process the MSG. On each subsequent scan of the MSG,
it checks the queue to see if there is room.
The message manager logic lets you control the number of MSGs that are enabled
at one time and enable subsequent MSGs in sequence. In this way, MSGs enter
and exit the queue in an ordered fashion and do not have to wait for room on the
queue to become available.
Message Manager Logic
The message manager logic sends three groups of MSGs.
•To make the example in this section easier to follow, each groups contains
only two MSGs.
•In your project, use more MSGs in each group, such as five.
•Use as many groups as needed to include all your MSGs.
The Msg_Group tag controls the enabling of each MSG.
•The tag uses the DINT data type.
•Each bit of the tag corresponds to a group of MSGs.
•For example, Msg_Group.0 enables and disables the first group of MSGs
(group 0).

20 Rockwell Automation Publication 1756-PM012D-EN-P - November 2011
Chapter 2 Manage Multiple Messages
Initialize the Logic
Restart the Sequence
Send the First Group of MSGs
If S:FS = 1 (first scan), then initialize the MSGs:
Msg_Group = 0, which disables all the MSGs.
Msg_Group.0 =1, which enables the first group of MSGs.
If the MSGs in group 2 (last group) are currently enabled (Msg_Group.2 = 1)
and Msg_4 is done or errored
and Msg_5 is done or errored
then restart the sequence of MSGs with the first group:
Msg_Group.2 = 0. This disables the last group of MSGs.
Msg_Group.0 = 1. This enables the first group of MSGs.
If Msg_Group.0 changes from 0 -> 1 then
send Msg_0.
send Msg_1.
Because a MSG instruction is a transitional instruction, it executes only when its rung-condition-in changes from
false to true.