Omron CPM2C-S100C Operation Manual page 45

CPM2C-S Structure and Operation
Interrupt Program
Execution
!Caution Although IORF(97) can be used in interrupt subroutines, you must be careful
When an interrupt is generated during execution of the main program, main
program execution is interrupted immediately and the interrupt program is
executed. The following diagram shows the cyclic operation of the CPM2C-S
when an interrupt program is executed.
Normally, the results of interrupt program execution are transferred to I/O
memory just after program execution (during I/O refreshing), but IORF(97)
can be used to refresh a specified range of I/O words during execution of the
interrupt program. The specified range of I/O words will be refreshed when
IORF(97) is executed.
The normal cycle time is extended by the time required for execution of the
interrupt program.
Refer to SECTION 7 Cycle Time and I/O Response Time for more details and
precautions on the cycle time.
Cycle
time
of the interval between IORF(97) executions. If IORF(97) is executed too fre-
quently, a fatal system error may occur (FALS 9F), stopping operation. The
interval between executions of IORF(97) should be at least 1.3 ms + total exe-
cution time of the interrupt subroutine.
Overseeing processes
Main program
I/O refreshing
RS-232C port servicing
Peripheral port servicing
Section 1-3
Interrupt generated.
Interrupt program
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