Rockwell Automation 1756 ControlLogix, 1756 GuardLogix, 1769 CompactLogix, 1769 Compact GuardLogix, 1789 SoftLogix Original Instructions

...

Programming Manual

Logix 5000 Controllers Messages

1756 ControlLogix, 1756 GuardLogix, 1769 CompactLogix, 1769 Compact GuardLogix, 1789 SoftLogix, 5069 CompactLogix, 5069 Compact GuardLogix, Studio 5000 Logix Emulate

Original Instructions

Logix 5000 Controllers Messages

personal injury or death, property damage, or economic loss.

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IMPORTANT

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.

temperatures.

for Personal Protective Equipment (PPE).

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2 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

Change

Topic

Updated branding.

Throughout

Change

Topic

of 1.1 KB.

on page 13

Summary of changes

This manual includes new and updated information. Use these reference tables to locate changed information.

Grammatical and editorial style changes are not included in this summary.

Global changes

This table identifies changes that apply to all information about a subject in the manual and the reason for the change. For example, the addition of new supported hardware, a software design change, or additional reference material would result in changes to all of the topics that deal with that subject.

New or enhanced features

This table contains a list of topics changed in this version, the reason for the change, and a link to the topic that contains the changed information.

Updated Legal notices. Legal notices on page 8

Each unconnected buffers uses 1.2 KB of memory instead

Get or Set the Number of Unconnected Buffers

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 3

Summary of changes Controller messages

Manage multiple messages

Send a message to multiple controllers

Index

Preface

Studio 5000 environment .......................................................................... 7

Additional resources ................................................................................... 7

Legal notices ................................................................................................ 8

Chapter 1

Introduction to Controller Messages ........................................................ 9

Supported data types .................................................................................. 9

Message Queue ...........................................................................................10

Cache list .....................................................................................................10

Unconnected buffers .................................................................................. 12

Guidelines ................................................................................................... 12

Get or set the number of unconnected buffers ........................................ 13

Get the number of unconnected buffers ............................................ 13

Set the number of unconnected buffers ............................................. 13

Convert between INTs and DINTs ............................................................ 15

Chapter 2

Introduction ............................................................................................... 17

Message manager logic ............................................................................. 17

Chapter 3

Introduction ............................................................................................... 21

Configure the I/O configuration .............................................................. 21

Define your source and destination elements ........................................ 22

Create the MESSAGE_ CONFIGURATION data type ............................ 22

Create the configuration array ..................................................................23

Get the size of the local array .................................................................... 24

Load the message properties for a controller .......................................... 25

Configure the message ............................................................................. 25

Step to the next controller ........................................................................ 26

Restart the sequence ................................................................................. 26

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 5

Resource

Description

at http://ab.rockwellautomation.com

and other certification details.

Studio 5000 environment

Additional resources

Preface

This manual shows how to program message (MSG) instructions to and from Logix 5000™ controllers. This manual is one of a set of related manuals that show common procedures for programming and operating Logix 5000 controllers.

For a complete list of common procedures manuals, refer to the

Logix 5000 Controllers Common Procedures Programming Manual, publication 1756- PM001.

The term Logix 5000 controller refers to any controller based on the Logix 5000 operating system.

The Studio 5000 Automation Engineering & Design Environment® combines

engineering and design elements into a common environment. The first element is the Studio 5000 Logix Designer® application. The Logix Designer application is the rebranding of RSLogix 5000® software and will continue to be the product to program Logix 5000™ controllers for discrete, process, batch, motion, safety, and drive-based solutions.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 7

The Studio 5000® environment is the foundation for the future of Rockwell Automation® engineering design tools and capabilities. The Studio 5000 environment is the one place for design engineers to develop all elements of their control system.

These documents contain additional information concerning related

Rockwell Automation products.

Industrial Automation Wiring and Grounding Guidelines, publication 1770-4.1

Product Certifications webpage, available

Provides general guidelines for installing a Rockwell Automation industrial system.

Provides declarations of conformity, certificates,

View or download publications at

http://www.rockwellautomation.com/literature

. To order paper copies of

Preface

Legal notices

technical documentation, contact the local Rockwell Automation distributor or sales representative.

Rockwell Automation publishes legal notices, such as privacy policies, license

agreements, trademark disclosures, and other terms and conditions on the

Legal Notices

page of the Rockwell Automation website.

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You can view the Rockwell Automation End User License Agreement (EULA) by opening the license.rtf file located in your product's install folder on your hard drive.

The default location of this file is:

C:\Program Files (x86)\Common Files\Rockwell\license.rtf.

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You can view a full list of all open source software used in this product and their corresponding licenses by opening the oss_license.txt file located your product's OPENSOURCE folder on your hard drive. This file is divided into these sections:

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The default location of this file is:

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8 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

You may obtain Corresponding Source code for open source packages included in this product from their respective project web site(s). Alternatively, you may obtain complete Corresponding Source code by contacting Rockwell Automation via the Contact form on the Rockwell Automation website:

http://www.rockwellautomation.com/global/aboutus/contact/contact.page. Please include "Open Source" as part of the request

text.

Example:

then execute a MSG instruction that sends data to another controller.

Description

Introduction to

Controller Messages

Supported data types

Chapter 1

Controller messages

This section describes how to transfer (send or receive) data between controllers by executing a message (MSG) instruction. It explains cache connections and buffers so you can correctly program the controller.

The following data types are supported when sending CIP messages.

• SINT

• INT

• DINT

• LINT

• REAL

In addition, you can send a message with any structure type that is predefined, module-defined, or user-defined.

For more information, see "Convert between INTs and DINTs on page 15

For complete details on programming a message instruction, see the LOGIX

5000 Controllers General Instruction Reference Manual, publication 1756-

RM003.

Execute a message (MSG) instruction If count_send = 1 and count_msg.EN = 0 (MSG instruction is not enabled)

This diagram shows how the controller processes MSG instructions.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 9

Chapter 1 Controller messages

the message remains enabled but is held until another controller scan.

If the MSG instruction

Then the MSG instruction

Description

The EW bit remains cleared.

The EW bit is set.

This type of message

And this communication method

Uses a connection

CIP with Source ID

Message Queue

Cache list

The controller scans the MSG instruction and its rung-condition-in goes true. The message passes to a throttle that has 16 positions. If the throttle is full,

The System-overhead time slice executes and the message is pulled from the throttle to the message queue.

Does not use a connection or the connection was not previously cached Uses an unconnected buffer to establish communication with the

Uses a connection and the connection is cached Does not use an unconnected buffer.

Communication occurs with the destination device.

destination device.

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 in the following illustration.

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 16 throttle positions exist. If all 16 are filled and a 17th message is executed, the

message is enabled. 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 no open positions exist yet.

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.

Depending on how you configure a MSG instruction, it may use a connection

to send or receive data.

CIP data table read or write — Your option PLC-2, PLC-3, PLC-5, or SLC (all types) CIP

10 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

(1)

1. CIP data table read or write messages can be connected or unconnected. However for most applications, it is recommended you leave CIP data table read

If you

Then

If you have this software version and firmware

Then you can cache

12.x or later

Up to 32 connections.

If the MSG instructions are to

And they are

Then

buffer.

EXAMPLE

Chapter 1 Controller messages

DH+ Yes

CIP generic — Your option

(2)

Block-transfer read or write — Yes

or write messages connected.

2. CIP generic messages can be connected or unconnected. However for most applications, it is recommended you leave CIP generic messages unconnected, unless you want to use the Large Connection option.

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.

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.

The controller has the following limits on the number of connections that you can cache.

revision

11.x or earlier • Block transfer messages for up to 16 connections.

• Other types of messages for up to 16 connections.

If several messages go to the same device, the messages may be able to share a connection.

Different devices — Each MSG instruction uses 1 connection. The same device, cached, and not a large

connection

Enabled simultaneously (same scan) Each MSG instruction uses 1 connection and 1 cached

buffer.

Not enabled simultaneously All MSG instructions use 1 connection and 1 cached

buffer. They share the connection and the buffer.

The same device, cached, and a large connection Enabled simultaneously (same scan) Each MSG instruction uses 1 connection and 1 cached

Not enabled simultaneously All MSG instructions use 1 connection and 1 cached

buffer. They share the connection and the buffer.

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 the 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 (for example, 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 use 2 cached connections.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 11

Chapter 1 Controller messages

Term

Definition

• Executes a MSG instruction that does not use a connection.

If all unconnected buffers are in use when an instruction leaves the message queue, an error occurs and data does not transfer.

Guideline

Details

• The tag cannot be part of an array or a user-defined data type.

MSG tag as either a controller scope or a Program Local scope tag.

If your message is to a device that uses 16-bit integers,

Logix 5000 controllers execute more efficiently and use less memory when working with 32-bit

Unconnected buffers

Guidelines

To establish a connection or process unconnected messages, the controller uses an unconnected buffer.

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.

The controller can have 10 to 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 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.

As you plan and program your MSG instructions, follow these guidelines.

For each MSG instruction, create a control tag. • Data type = MESSAGE

• Scope = controller

Keep the source and destination data at the controller scope.

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.

Cache the connection for those MSG instructions that execute most frequently, up to the maximum number permissible for your controller revision.

If you want to enable more than 16 MSGs at one time, use a management strategy to ensure some MSG instructions are not delayed entering the queue.

A MSG instruction can access only tags that are in the Controller Tags folder (controller scope). Tip: On CompactLogix 5370, ControlLogix 5570, Compact GuardLogix 5370, and GuardLogix 5570 controllers, enter an MSG tag only as a controller scope tag. In versions 31 and later of the Logix Designer application, on CompactLogix 5380, CompactLogix 5480, ControlLogix 5580, Compact GuardLogix 5380, and GuardLogix 5580 controllers, enter an

integers (DINTs). See Convert Between INTs and DINTs on page 15.

Execution time is optimized when the controller does not open a connection each time the message executes.

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.

12 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

Keep the number of unconnected and uncached MSGs less

On this tab

For this item

Type or choose

Class

304

Instance

In this element

Enter

source_array

[2]

Communication

Path

slot_number_of_controller

On this tab

For this item

Type or select

Get or set the number of

than the number of unconnected buffers.

unconnected buffers

The controller can have 10 to 40 unconnected buffers. The default number is 10.

• If all unconnected buffers are in use when an instruction leaves the message queue, an error occurs, the data is not transferred.

• You can increase the number of unconnected buffers (up to 40), provided you continue to adhere to the previous guideline.

• To increase the number of unconnected buffers, see "

Buffers on page 13".

•

Chapter 1 Controller messages

Get or Set the Number of Unconnected

To determine or change the number of unconnected buffers, use a MSG instruction.

• The range is 10 to 40 unconnected buffers.

• The default number is 10.

• Each unconnected buffers uses 1.2 KB of memory.

Get the number of unconnected buffers

Configuration Message Type CIP Generic

Service Type Custom Service Code 3

Attribute 0 Source Element

Source Length (bytes) 4 (Write 4 SINTs.) Destination Element

To determine the number of unconnected buffers that are currently available, configure a Message (MSG) instruction as follows.

source_array

source_array source_array

source_array

destination_array

destination_array[

where data type = SINT[4]

[0] 1 [1] 0

[3] 0

where data type = SINT[10] (Leave all values = 0.)

6] = current number of unconnected buffers

Set the number of unconnected buffers

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 13

As a starting value, set the number of unconnected buffers equal to the number of unconnected and uncached messages enabled at one time plus 5. The additional 5 buffers provide a cushion in case you underestimate the

number of messages that are enabled at once.

To change the number of unconnected buffers of the controller, configure a Message (MSG) instruction as follows.

Configuration Message Type CIP Generic

Service Type Custom

Chapter 1 Controller messages

Class

304

Attribute

In this element

Enter

source_array

[2]

= 0.)

or for earlier Logix 5000 controllers: 1,

slot_number_of_controller

EXAMPLE

Set the number of unconnected buffers

then MSG instruction sets the number of unconnected buffers = Source_Array[4].

Service Code 4

Instance 1

Source Element

source_array

Source Length (bytes) 8 (Write 8 SINTs.) Destination Element

destination_array

Communication Path THIS

If S:FS = 1 (first scan) then set the number of unconnected buffers for the controller.

Source_Array[0] = 1 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)

source_array source_array

source_array source_array source_array

where data type = SINT[8]

[0] 1 [1] 0

[3] 0 [4] Number of unconnected

buffers that you want.

[5] 0 [6] 0 [7] 0

where data type = SINT[6] (Leave all the values

14 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

Tag Name

Type

Description

UCB_Set

MESSAGE

Control tag for the MSG instruction.

buffers that you want.

Data from the

Buffer of INTs

DINTs for use in the

Word 1

INT_Buffer[0]

DINT_Array[0]

Word 2

INT_Buffer[1]

DINT_Array[1]

Word 3

INT_Buffer[2]

DINT_Array[2]

Description

DINTs from the project

Buffer of INTs

Data for the Description

Convert between

INTs and DINTs

Source_Array SINT[8] Source values for the MSG instruction, including the number of unconnected

Chapter 1 Controller messages

In the Logix 5000 controller, use the DINT data type for integers whenever possible. Logix 5000 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 the message and DINTs throughout the project. This increases the efficiency of your project.

Read 16-bit integers

device

The Message (MSG) instruction reads 16-bit integers (INTs) from the device and stores them in a temporary array of INTs.

A File Arith/Logical (FAL) instruction converts the INTs to DINTs for use by other instructions in your project.

Write 16-bit integers

DINT_Array[0]

INT_Buffer[0]

project

device

Word 1

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 15

DINT_Array[1]

DINT_Array[2]

INT_Buffer[1]

INT_Buffer[2]

Word 2

Word 3

Chapter 1 Controller messages

The MSG instruction writes the INTs from the temporary array to the device.

EXAMPLE

The FAL instruction sets DINT_Array = INT_Buffer. This converts the values to 32-bit integers (DINTs).

integers (INTs).

An FAL instruction converts the DINTs from the Logix 5000 controller to INTs.

If Msg_1.DN =1 (MSG instruction has read the data)

then reset the FAL instruction.

Read integer values from a PLC-5 controller If Condition_1 = 1 and Msg_1.EN = 0 (MSG instruction is not enabled)

then read 3 integers from the PLC-5 controller and store them in INT_Buffer (3 INTs).

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

If Control_2.DN = 1 (FAL instruction has converted the DINTs to INTs)

and Msg_2.EN = 0 (MSG instruction is not enabled)

then write the integers in INT_Buffer (3 INTs) to the PLC-5 controller.

16 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

EXAMPLE

Message manner logic

Msg_Group.0 =1, which enables the first group of MSGs.

Introduction

Message manager logic

Chapter 2 Manage multiple messages

Chapter 2

Manage multiple messages

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

prevents some of the messages from entering the message queue. If this occurs, the MSG is held until room exists on the queue for the controller to process the MSG. On each subsequent scan of the MSG, it checks the queue to see if room exists.

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 order and do not need to wait for room on the queue to become available.

The message manager logic sends three groups of MSGs. 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).

To make the example easier to follow, each group contains only two MSGs. In your project, use more MSGs in each group, such as five.

Initialize the logic If S:FS = 1 (first scan) then initialize the MSGs:

Msg_Group = 0, which disables all MSGs.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 17

Chapter 2 Manage multiple messages

Msg_Group.1 = 1. This enables the next group of MSGs.

Restart the sequence If the MSGs in group 2 (last group) are currently enabled (Msg_Group.2 = 1) and Msg_4 is in the state of done or error and Msg_5 is in the state of done or error 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.

Send 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.

Enable the second group of MSGs If the MSGs in group 0 are currently enabled (Msg_Group.0 = 1) and Msg_0 is in the state of done or error and Msg_1 is in the state of done or error then:

Msg_Group.0 = 0. This disables the current group of MSGs.

Send the second group of MSGs If Msg_Group.1 changes from 0 -> 1 then

send Msg_2. send Msg_3.

18 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

Msg_Group.2 = 1. This enables the next group of MSGs.

send Msg_3.

Enable the next group of MSGs If the MSGs in group 1 are currently enabled (Msg_Group.1 = 1) and Msg_2 is in the state of done or error and Msg_3 is in the state of done or error then:

Msg_Group.1 = 0. This disables the current group of MSGs.

Chapter 2 Manage multiple messages

Send the next group of MSGs

If Msg_Group.1 changes from 0 -> 1 then

send Msg_2.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 19

IMPORTANT

If the message

Then the RemoteElement is the

Index for the asterisk [*].

In the Open Project dialog box, click MSG_To_multiple_Controllers.acd, and click Open.

Introduction

Configure the I/O

Chapter 3

Send a message to multiple controllers

You can program one message instruction to communicate with multiple controllers. To reconfigure a MSG instruction during runtime, write new

values to the members of the MESSAGE data type.

In the MESSAGE data type, the RemoteElement member stores the tag name or address of the data in the controller that receives the message.

Reads data Source element Writes data Destination element

If you use an asterisk [*] to designate the element number of the array, the value in provides the element number.

The Index

configuration

box is available only when you use an asterisk [*] in the Source Element or Destination Element. The instruction substitutes the value of

Tip: To copy the previous components from a sample project, take the following steps.

a. On the Help menu, click Quick Start. b. On the Quick Start window, in the left navigation pane, expand Controller Projects, and

click Open Sample Project.

Although not required, it is recommended that you add the communication modules and remote controllers to the I/O configuration of the controller. This makes it easier to define the path to each remote controller.

For example, once you add the local communication module, the remote communication module, and the destination controller, clicking Browse lets you select the destination.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 21

Chapter 3 Send a message to multiple controllers

Message Path Browser

[0] 1756-CNB/x Local_CNB

Name of Remote Controller

Tag or Address of Data in Remote Controller

Tag in This Controller

Tag Name

Type

length

is the number of elements in the local array.

Define your source and

Create the MESSAGE_

Path: peer_controller

peer_controller

I/O Configuration

destination elements

2 [0] 1756-CNB/x chassis_b

[1] 1756-L55/x peer_controller

An array stores the data that is read from or written to each remote controller. Each element in the array corresponds to another remote controller.

1. Use the following worksheet to organize the tag names in the local and remote controllers.

local_array[0] local_array[1] local_array[2] local_array[3]

CONFIGURATION data type

22 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

2. Create the local_array tag, which stores the data in this controller.

local_array

data_type [length]

where:

data_type

such as DINT, REAL, or STRING.

is the data type of the data that the message sends or receives,

Create a user-defined data type to store the configuration variables for the message to each controller.

• Some of the required members of the data type use a string data type.

• The default STRING data type stores 82 characters.

• If your paths or remote tag names or addresses use less than

82 characters, you have the option of creating a new string type that stores fewer characters. This lets you conserve memory.

• To create a string type, click File > New Component > String Type.

• If you create a string type, use it in place of the STRING data type.

Data Type: MESSAGE_CONFIGURATION

Description: Configuration properties for a message to another controller

Members

Name

Data Type

Style

Description

Tag Name

Type

Scope

1.Number indicates the number of controllers to send the message

Create the

Chapter 3 Send a message to multiple controllers

To store the configuration variables for the message to each controller, expand the Assets > Data Types folder, right-click User Defined, and select New Data Type to create the following user-defined data type.

Name: MESSAGE_CONFIGURATION

configuration array

Path STRING RemoteElement STRING

Store the configuration properties for each controller in an array. Before each execution of the MSG instruction, your logic loads new properties into the instruction. This sends the message to another controller.

1. To store the configuration properties for the message, create the

following array.

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 23

message_config MESSAGE_CONFIGURATION[

number

(1)

]

Any

Chapter 3 Send a message to multiple controllers

Tag Name

Value

message_config

{…}

message_config[0].RemoteElement

Get the size of

2. In the message_config array, enter the path to the first controller that

3. In the message_config array, enter the tag name or address of the data

receives the message.

in the first controller to receive the message.

the local array

4. Enter the path and remote element for each additional controller.

message_config[0] {…}

message_config[0].Path

message_config[1] {…}

message_config[1].Path message_config[1].RemoteElement

The SIZE instruction:

• Counts the number of elements in local_array.

• Counts the number of elements in Dimension 0 of the array. In this

case, that is the only dimension.

24 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

On this tab

If you want to

For this item

Type or select

Configuration

Read (receive) data from the other

Message Type

The read-type that corresponds to the other controllers

Destination Element

local_array[*]

Index

Load the message

Configure the message

properties for a controller

Chapter 3 Send a message to multiple controllers

Local_array_length (DINT) stores the size (number of elements) of local_array. This value tells a subsequent rung when the message is sent to all controllers and to start with the first controller again.

1. The XIO instruction conditions the rung to continuously send the

message.

2. The first COP instruction loads the path for the message. The value of index determines which element the instruction loads from message_config. The instruction loads one element from message_config.

3. The second COP instruction loads the tag name or address of the data in the controller that receives the message. The value of index determines which element the instruction loads from message_config. The instruction loads one element from message_config.

controllers

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 25

The following table explains how to configure the message.

Source Element Tag or address that contains the data in the first controller Number Of Elements 1

Message Type The write-type that corresponds to other controllers

Chapter 3 Send a message to multiple controllers

Step to the next controller

Restart the sequence

Write (send) data to the other controllers

Communication — Path Path to the first controller

Source Element local_array[*] Index 0

Number Of Elements 1 Destination Element Tag or address that contains the data in the first controller

Cache Connections Clear the Cache Connections check box (more efficient since this

procedure continuously changes the path of the message)

After the MSG instruction sends the message, the following actions occur.

1. The first ADD instruction increments the index. This lets the logic load

the configuration properties for the next controller into the MSG instruction.

2. The second ADD instruction increments the LocalIndex member of the MSG instruction. This lets the logic load the value from the next controller into the next element of local_array.

When the index equals the local_array_length, the controller sends the message to all other controllers.

1. The first CLR instruction sets the index equal to 0. This lets the logic

load the configuration properties for the first controller into the MSG instruction and start the sequence of messages again.

2. The second CLR instruction sets the LocalIndex member of the MSG instruction equal to 0. This lets the logic load the value from the first controller into the first element of local_array.

26 Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

Index

array

controller configuration 23

block transfer

guidelines 12

buffer

for unconnected messages 12, 13

Index

controller 9 convert between 16 and 32-bit data 15 example illustration 9 limits 10 manage multiple messages 17 processing 9 queue 10 to a single controller 9 to multiple controllers 21 unconnected buffer 12, 13

processing

message 9

queue

message 10

cache

connection 10

communicate

message instruction 9 other controllers 9

connection

cache 10

controller

message properties 25 messages 9

data type

convert data 15 message configuration 22

guidelines

messages 12

tag

guidelines for messages 12 organize for message 9

ladder logic

manage messages 17

message

cache connection 10

Rockwell Automation Publication 1756-PM012I-EN-P - September 2020 27

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Rockwell Automation Publication 1756-PM012I-EN-P - September 2020

Rockwell Automation 1756 ControlLogix, 1756 GuardLogix, 1769 CompactLogix, 1769 Compact GuardLogix, 1789 SoftLogix Original Instructions

Specifications and Main Features

Frequently Asked Questions

User Manual

Logix 5000 Controllers Messages

Important User Information

Summary of changes

Table of Contents

Studio 5000 environment

Additional resources

Preface

Legal notices

Controller Messages

Supported data types

Message Queue

Cache list

Unconnected buffers

Guidelines

Get the number of unconnected buffers

Set the number of unconnected buffers

Introduction

Message manager logic

Chapter 2

Introduction

Configure the message

Step to the next controller

Restart the sequence

Index