Mitsubishi Electric L02SCPU User's Manual And Reference page 60

(3) Operation when an interrupt factor occurs
The following restrictions are applied to the interrupt program depending on the interrupt factor occurrence
timing.
(a) When an interrupt factor occurs before the interrupt program execution status is
enabled
The CPU module stores the interrupt factor occurred. As soon as the interrupt program execution status is
enabled, the CPU module executes the interrupt program corresponding to the stored interrupt factor.
When the same interrupt factor occurs more than one time before the interrupt program execution status is
enabled, the interrupt factors of I0 to I15, I28 to I31, I45, I50 to I255, and fixed scan execution type programs
are stored only once. Note that all interrupt factors occurred are discarded if they are masked by the IMASK
instruction.
(b) When an interrupt factor occurs in the STOP or PAUSE status
The CPU module executes the interrupt program as soon as the interrupt program execution status is enabled
after the CPU module status is changed to RUN.
Main routine
program
Interrupt
program
58
Interrupt factor occurred.
Main routine
program
Interrupt
program
Not executed since
execution status of the
interrupt program is
disabled (DI).
Interrupt factor occurred.
Not executed since
the CPU module is in
the STOP or PAUSE
status.
Interrupt enabled (EI)
Execution
Executed when execution
status of the interrupt program
becomes enabled.
STOP/ PAUSE RUN
RUN
Interrupt enabled (EI)
Execution
Executed after the CPU module exits
the STOP or PAUSE status and enters
the RUN status, and execution status of
the interrupt program becomes enabled.