Rockwell Automation Logix5000 Controllers Tasks, Programs, and Routines Programming Manual - Manual (Page 60)

Chapter 2 Manage event tasks
2. Produced tag properties
On the New Tag dialog box for the produced tag, click Connection to open the Produced Tag Connection dialog box. Check
Send Data State Change Event to Consumer(s).
If you leave this check box cleared (unchecked), the producing controller triggers the event task at the end of any task that
automatically updates local outputs. In other words, the task scan triggers the event in addition to the IOT instruction.
3. IOT instruction
Use an IOT instruction at the point in your logic where you want to trigger the event task.
The IOT instruction overrides the RPI for the tag and immediately sends the event trigger and the data of the tag.
Checklist for the consumer controller
For This Make Sure You
1. Buffer of data If you want to make sure that the controller does not use data from the consumed tag while the data is changing, use a copy of the
consumed tag. Use the event task to copy the data.
2. Task priority
Configure the event task as the highest priority task.
If a periodic task has a higher priority, the event task may have to wait until the periodic task is finished.
3. Number of event tasks Limit the number of event tasks. Each additional task reduces the processing time available for other tasks. This could cause an overlap.
4. Automatic output processing For an event task, you can typically disable automatic output processing (default). This reduces the elapsed time of the task.
60 Rockwell Automation Publication 1756-PM005-EN-P - October 2014