Owner manual

Rockwell Automation Publication 1756-UM533C-EN-P - February 2011 145
Chapter 10
Unlatch Alarms and Reconfigure Modules
By Using Ladder Logic
Introduction
The information in this chapter applies only to the 1756-IF8H and 1756-OF8H
modules. Alarms are not available in the 1756-IF16H module.
These topics are discussed in this chapter.
Using Message
Instructions
In ladder logic, you can use message instructions to send occasional services to any
ControlLogix I/O module. Message instructions send an explicit service to the
module, causing specific behavior to occur, for example, unlatching a high alarm.
Message instructions maintain the following characteristics:
• Messages use unscheduled portions of system communication bandwidth.
• One service is performed per instruction.
• Performing module services does not impede module functionality, such as
sampling inputs or applying new outputs.
Topic Page
Using Message Instructions 145
Unlatch Alarms in the 1756-IF8H Module 150
Unlatch Alarms in the 1756-OF8H Module 152
Reconfigure a Module 154