Interrupt From Modules; System Switching In Backup Mode; System Switching In Separate Mode; When The Operation Mode Is Switched To The Separate Mode - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

29.2

Interrupt from Modules

The following describes the precautions for interrupts from modules.

System switching in backup mode

When the old control system is switched to the new standby system
The old control system retains the interrupt factors that have occurred even after the system is switched to the new standby
system by system switching before execution of an interrupt program. After the systems are switched again, the interrupt
program of an interrupt factor that the old control system has retained will be executed.
Since the interrupt factor that has occurred on the old control system is not inherited to the new control system, the interrupt
program of an interrupt factor that has occurred on the old control system will not be executed on the new control system.
When the old standby system is switched to the new control system
The old standby system retains the interrupt factors that have occurred. After the old standby system is switched to the new
control system by system switching, the interrupt program of an interrupt factor that the old standby system has retained will
be executed on the new control system.
When the old standby system has retained multiple interrupt factors, the scan time may greatly increase.

System switching in separate mode

When the old control system is switched to the new standby system
The old control system executes the interrupt factors that the old control system has retained even after the system is
switched to the new standby system by system switching before execution of an interrupt program.
When the old standby system is switched to the new control system
The old standby system retains the interrupt factors that have occurred. The new control system executes the interrupt
program of an interrupt factor that the old standby system has retained regardless of the system switching operation.

When the operation mode is switched to the separate mode

For the control system
The control system retains the interrupt factors before switching to the separate mode. After the operation mode is switched to
the separate mode, the control system executes the interrupt programs of the interrupt factors that have occurred in the
backup mode.
For the standby system
The interrupt factors that the standby system has retained before switching to the separate mode will be discarded. Therefore,
after the operation mode is switched to the separate mode, the interrupt programs of the interrupt factors that have occurred
before switching to the separate mode will not be executed.
29 PRECAUTIONS ON PROGRAMMING
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29.2 Interrupt from Modules