20
Structure and Operation Section 1-3
Interrupt Program
Execution
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
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 PC Operations and Processing Time in the Programming
Manual (W353) for more details and precautions on the cycle time.
!Caution Although IORF(97) can be used in interrupt subroutines, you must be careful
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.
Immediate Refreshing IORF(97) can be executed in the program to refresh a specified range of I/O
words. The specified I/O words will be refreshed when IORF(97) is executed.
IORF(97) can be used to refresh I/O from the main program or the interrupt
program.
Cycle
To Next Page
Loading...
Need help?
General
