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Rockwell Automation Publication 1769-UM021G-EN-P - October 2015
Chapter 10
Develop Applications
Monitoring Controller Status
The CompactLogix controller uses Get System Value (GSV) and Set System
Value (SSV) instructions to get and set (change) controller data. The controller
stores system data in objects. There is no status file, as in the PLC-5
®
processor.
The GSV instruction retrieves the specified information and places it in the
destination. The SSV instruction sets the specified attribute with data from the
source. The instructions are available from the Input/Output tab of the
Instruction tool bar.
Figure 51 - GSV and SSV Instructions for Monitoring
When you add a GSV/SSV instruction to the program, the object classes, object
names, and attribute names for each instruction are displayed. For the GSV
instruction, you can get values for the available attributes. For the SSV
instruction, only those attributes you are allowed to set are displayed.
Some object types appear repeatedly, so you have to specify the object name. For
example, there can be several tasks in your application. Each task has its own Task
object that you access by the task name.
There are several objects and attributes that you can use the GSV and SSV
instructions to monitor and set the system. For more information about GSV
instructions, SSV instructions, objects, and attributes see the Logix5000
Controllers General Instructions Reference Manual, publication
