Rockwell Automation Logix5000 Controllers Tasks, Programs, and Routines Programming Manual - Manual (Page 48)

Chapter 2 Manage event tasks
Checklist for a motion group task
For This Make Sure You
1. Scan time
Make sure the scan time of the event task is significantly less than the base update period of the motion group. Otherwise, a task
overlap could occur.
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 that is 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.
To let the registration input of an axis trigger an event task, use the Axis
Registration 1 or Axis Registration 2 triggers.
Let an event trigger this task.
Let registration input 1….
…of this axis trigger the task.
Interrupt all other tasks.
When the task is done, do not update digital outputs in the local chassis.
When the specified registration input reaches its trigger condition, it triggers the
event task.
Axis registration trigger
48 Rockwell Automation Publication 1756-PM005-EN-P - October 2014