Monday, July 26, 2010

Interrupt Functions of CPM2A Programmable Logic Controllers





The CPM2A provides the following kinds of interrupt processing.

Interrupt Inputs
Interrupt programs are executed when inputs to the CPU unit’s built-in input points (00003 to 00006) are turned from OFF to ON. Interrupt subroutine numbers 000 to 003 allocated to input pins 00003 to 00006.

Interval Timer Interrupts
Interval timer interrupt programs are executed with the precision of 0.1 ms. Interrupt subroutine numbers 000 to 049 are allocated by instructions.

Count-up Interrupts Using the High-Speed Counter
Input signals to the CPU unit’s built-in input points (00003 to 00006) are counted at high speed (2 KHz), and the normal program is stopped and an interrupt program is executed. Interrupt subroutine numbers 000 to 003 are allocated to input points 00003 to 00006.

Count-check Interrupt Using the High-Speed Counter
Pulse input to the CPU unit built-in input points (00003 to 00006) are counted at high speed (20 KHz/5 KHz), and an interrupt program is executed when the present values matches the target value or falls within a given range. Interrupt subroutine numbers 000 to 049 are allocated by instructions.

The order of priority for interrupts is as follows:
priority for interrupts Functions of CPM2A
If an interrupt with a higher priority is generated. During interrupt program execution, the interrupt that is currently being processed will be stopped and the new interrupt will be processed first. Then the original interrupt will resumed after the higher priority interrupt processing has been completed.

If interrupt of the same priority are generated simultaneously, they will be processed in the following order: Interrupt inputs --> Interrupt input 1 --> Interrupt input 2 --> Interrupt input 3 --> (including count-up mode) Interval timer interrupt --> High-Speed counter interrupt.



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