Mitsubishi Electric melsec q00ujcpu User Manual page 49

(c) When multiple interrupt factors occur simultaneously in the interrupt program execution
enabled status
The interrupt programs are executed in the order of interrupt pointers (I ) with high priority.
( Section 9.11.1)
Other interrupt programs have to wait until processing of the interrupt program being executed is
completed.
Main routine
program
Interrupt
High
program (I50)
Interrupt
program (I100)
Interrupt
Low
program (I150)
(d) When the same interrupt factor as that of the interrupt program being executed occurs
When the same interrupt factor as that of the interrupt program being executed occurs more than
one time before completion of interrupt program processing, the interrupt factors of I0 to I15, I45,
and I50 to I255 are stored only once, and then the interrupt program corresponding to each stored
interrupt factor is executed after completion of current interrupt program execution
The interrupt factors of I28 to I31 and fixed scan execution type programs are all stored, and then all
the interrupt programs corresponding to interrupt factors are executed after completion of current
interrupt program execution.
2 - 10
Interrupt
enabled (EI)
Figure 2.13 When multiple interrupt factors occur simultaneously
Simultaneous occurrence of
multiple interrupt factors
I50 I100
I150
Execution
IRET
Execution
Wait to be
IRET
processed
Wait to be processed
Execution
IRET
.