Chapter 4 CPU modules MASTER-K
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3) PDI (Process driven interrupt)
PDI occurs when the input status of interrupt module is changed from OFF to ON or from
ON to OFF. (Select by DIP switch setting) Since K200S does not have interrupt module,
PDI will occur when the input assigned as interrupt input by parameter setting is changed
from OFF to ON.
The execution order of multiple interrupts is similar as TDI. The following figure shows an
example of execution order of multiple PDI.
Scan Program
Interrupt routine 0
Interrupt routine 1
1
3
5
7
8
2
4
Interrupt routine 2
6
PDI
PDI
PDI
2 4 6
9
Program starts
Interrupt 2 occurs
Stop main program and run PDI routine 2
Interrupt 0 occurs (higher priority)
Stop routine 2 and execute routine 0
Interrupt 1 occurs (lower priority)
Finish routine 0 and execute routine 1
Finish routine 1 and resume routine 2
Finish routine 2 and back to main program
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