Allen-Bradley Logix5000 Series Owner's manual

Logix5000 Controllers I/O and Tag Data
Catalog Numbers 1756 ControlLogix, 1756 GuardLogix,
1768 Compact GuardLogix, 1769 CompactLogix, 1789 SoftLogix,
PowerFlex with DriveLogix
Programming Manual

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, RSLogix 5000, Logix5000, RSLinx Classic, RSLinx Enterprise, PanelView, PLC-2, PLC-5, SLC, CompactLogix, ControlLogix, GuardLogix, FlexLogix, DriveLogix, SoftLogix,
Rockwell Software, FactoryTalk Security, 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.
IMPORTANT
Identifies information that is critical for successful application and understanding of the product.
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.

3Publication 1756-PM004C-EN-P - October 2009 3
Summary of Changes
Introduction
The release of this document contains new information.
New Information
New information is marked by change bars in the side column, as shown to
the right.
Section Changes
Chapter 1 New information and examples for electronic keying.
Chapter 4 Procedures and descriptions for the external access and
constant tag attributes that control access to
controller tags.

4Publication 1756-PM004C-EN-P - October 2009
Summary of Changes
Notes:

5Publication 1756-PM004C-EN-P - October 2009 5
Table of Contents
Preface Purpose of This Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 1
Communicate with I/O Modules
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Requested Packet Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Communication Format. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Direct or Rack-Optimized Connection . . . . . . . . . . . . . . . . . . . . . 11
Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Electronic Keying. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Address I/O Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Buffer I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Chapter 2
Organize Tags
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Tag Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Data Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Guidelines for Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Create a Tag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Create an Array. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Configure an Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Create a User-defined Data Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Guidelines for User-defined Data Types . . . . . . . . . . . . . . . . . . . . 40
Create a User-defined Data Type . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Describe a User-defined Data Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Activate Pass-Through and Append Descriptions. . . . . . . . . . . . . 43
Paste a Pass-Through Description . . . . . . . . . . . . . . . . . . . . . . . . . 44
Address Tag Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Alias Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Display Alias Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Assign an Alias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Assign an Indirect Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Array Subscript Out of Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Tag Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Language Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Chapter 3
Force I/O
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Enable Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Disable or Remove a Force. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Check Force Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
FORCE Status Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
GSV Instruction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
When to Use I/O Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

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Table of Contents
Force an Input Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Force an Output Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Add an I/O Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Remove or Disable Forces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Remove an Individual Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Disable All I/O Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Remove All I/O Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Chapter 4
Data Access Control
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
External Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Configure External Access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
External Access Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Configure External Access in the New Tag Dialog Box . . . . . . . . 66
Set Up External Access in the Tag Properties Dialog Box . . . . . . 68
View and Select External Access Status
on the Tag Editor Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
‘Go To’ Search Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
External Access Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
User-defined Type Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Add-On Instructions External Access Considerations . . . . . . . . . . . . 74
Tag Mapping Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Imported Tag Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Constant Value Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Configure Constant Tags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Set Up a Constant in the New Tag Dialog Box . . . . . . . . . . . . . . . 80
Configure a Constant in the Tag Properties Dialog Box . . . . . . . . 81
Designate a Constant in the Tag Editor . . . . . . . . . . . . . . . . . . . . . 82
Constant Checkbox Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Add-On Instructions Constant Value Considerations . . . . . . . . . . . . . 85
Index

Publication 1756-PM004C-EN-P - October 2009 7
Preface
Purpose of This Manual
This manual shows how to access I/O and tag data in 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, refer to the
Logix 5000 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.

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Preface
Notes:

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Chapter 1
Communicate with I/O Modules
Introduction
To communicate with an I/O module in your system, you add the module to
the I/O Configuration folder of the controller.
When you add the module, you also define a specific configuration for the
module. While the configuration options vary from module to module, these
are some common options that you typically configure:
•Requested Packet Interval
•Communication Format
•Electronic Keying
Add I/O modules here.

10 Publication 1756-PM004C-EN-P - October 2009
Chapter 1 Communicate with I/O Modules
Requested Packet Interval
The Logix5000 controller uses connections to transmit I/O data.
In Logix5000 controllers, I/O values update at a period that you configure via
the I/O configuration folder of the project. The values update asynchronous
to the execution of logic. At the specified interval, the controller updates a
value independently from the execution of logic.
•Programs within a task access input and output data directly from
controller-scoped memory.
•Logic within any task can modify controller-scoped data.
•Data and I/O values are asynchronous and can change during the
course of a task’s execution.
•An input value referenced at the beginning of a task’s execution can be
different when referenced later.
•To prevent an input value from changing during a scan, copy the value
to another tag and use the data from there (buffer the values).
Term Definition
Connection A communication link between two devices, such as between a controller and an I/O module, PanelView
terminal, or another controller.
Connections are allocations of resources that provide more reliable communications between devices than
unconnected messages. The number of connections that a single controller can have is limited.
You indirectly determine the number of connections the controller uses by configuring the controller to
communicate with other devices in the system. The following types of communication use connections:
•I/O modules
•produced and consumed tags
•certain types of Message (MSG) instructions (not all types use a connection)
Requested packet
interval (RPI) The RPI specifies the period at which data updates over a connection. For example, an input module sends data to a controller at the RPI that you assign to the module.
•Typically, you configure an RPI in milliseconds (ms). The range is 0.2 ms (200 microseconds)…750 ms.
•If a ControlNet network connects the devices, the RPI reserves a slot in the stream of data flowing across the
ControlNet network. The timing of this slot may not coincide with the exact value of the RPI, but the control
system guarantees that the data transfers at least as often as the RPI.
ATTENTION
Make sure that data memory contains the appropriate values
throughout a task’s execution. You can duplicate or buffer data
at the beginning of the scan to provide reference values for
your logic.