288 Rockwell Automation Publication 2080-UM002K-EN-E - March 2019
Appendix D User Interrupts
An interrupt must be configured and enabled to execute. When any one of the
interrupts is configured (and enabled) and subsequently occurs, the user
program:
1. suspends its execution of the current POU,
2. performs a predefined POU based upon which interrupt occurred, and
3. returns to the suspended operation.
Specifically, if the controller program is executing normally and an interrupt
event occurs:
1. the controller stops its normal execution.
2. determines which interrupt occurred.
3. goes immediately to the beginning of the POU specified for that User
Interrupt.
4. begins executing the User Interrupt POU (or set of POU/function blocks
if the specified POU calls a subsequent function block).
5. completes the POU.
6. resumes normal execution from the point where the controller program
was interrupted
When Can the Controller Operation be Interrupted?
The Micro830 controllers allow interrupts to be serviced at any point of a
program scan. Use UID/ UIE instructions to protect program block which
should not be interrupted.
Priority of User Interrupts
When multiple interrupts occur, the interrupts are serviced based upon their
individual priority.
Interrupt Operation Example
POU 2 is the main control program.
POU 10 is the interrupt routine.
• An Interrupt Event occurs at rung
123.
• POU 10 is executed.
• POU 2 execution resumes
immediately after POU 10 is
scanned.
rung 0
rung 123
rung 275
POU 2
POU 10
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