Rockwell Automation 2080-LC50 Micro830 and Micro850 Programmable Controllers User Manual - Manual (Page 229)

Rockwell Automation Publication 2080-UM002F-EN-E - December 2013 213
User Interrupts Appendix D
When an interrupt occurs and another interrupt(s) has already occurred but has
not been serviced, the new interrupt is scheduled for execution based on its
priority relative to the other pending interrupts. At the next point in time when
an interrupt can be serviced, all the interrupts are executed in the sequence of
highest priority to lowest priority.
If an interrupt occurs while a lower priority interrupt is being serviced (executed),
the currently executing interrupt routine is suspended, and the higher priority
interrupt is serviced. Then the lower priority interrupt is allowed to complete
before returning to normal processing.
If an interrupt occurs while a higher priority interrupt is being serviced
(executed), and the pending bit has been set for the lower priority interrupt, the
currently executing interrupt routine continues to completion. Then the lower
priority interrupt runs before returning to normal processing.
The priorities from highest to lowest are:
User Fault Routine highest priority
Event Interrupt0
Event Interrupt1
Event Interrupt2
Event Interrupt3
High-Speed Counter Interrupt0
High-Speed Counter Interrupt1
High-Speed Counter Interrupt2
High-Speed Counter Interrupt3
High-Speed Counter Interrupt4
High-Speed Counter Interrupt5
Event Interrupt4
Event Interrupt5
Event Interrupt6
Event Interrupt7
Selectable Timed Interrupt0
Selectable Timed Interrupt1
Selectable Timed Interrupt2
Selectable Timed Interrupt3
Plug-In Module Interrupt0, 1, 2, 3, 4 lowest priority