Mitsubishi Electric MELSEC iQ-R Series User Manual page 121

■If an interrupt factor with the same or a lower priority occurs while the interrupt program is
being executed
• For I0 to I15 and I50 to I1023
The interrupt factor that has occurred is memorized. After the running interrupt program finishes, the interrupt program
corresponding to the factor will be executed. Even if the same interrupt factor occurs multiple times, it will be memorized only
once.
Main routine program
I0 interrupt program
High
I50 interrupt program
I80 interrupt program
I100 interrupt program
Low
Priority level of interrupt: I0 = I50 = I80
(1) The second and following interrupt factors that occur while interrupts have been disabled (DI) are not memorized.
(2) After the interrupt in execution is completed, interrupts are executed in order from I50 because it has a higher priority. Although both I50 and I80 have the
same priority level, I50 is executed ahead of I80 because I50 has a higher priority order.
(3) I80 is executed. (I50 is not executed for the second time.)
(4) I100 is executed. (I80 is not executed for the second time.)
• For I45
The interrupt factor that has occurred is memorized. After the running interrupt program finishes, the I45 interrupt program will
be executed. Even if the I45 interrupt occurs multiple times, its interrupt factor will be memorized only once.
Main routine program
High
I49 interrupt program
I45 interrupt program
I44 interrupt program
Low
Priority level of interrupt: I45 = I44
Mc: Multiple CPU synchronization cycle
(1) The interrupt factor is memorized.
(2) The second and following interrupt factors that occur while interrupts have been disabled (DI) are not memorized.
(3) After I49 that has a higher priority level is completed, I45 is executed.
(4) Because both I44 and I45 have the same priority level, the interrupt is executed after I44 is completed.
(5) The interrupt is executed because I49 and I44 have been completed.
I0
I100 I80 I50 I100 I80 I50
(2)
I49
(1)
I45 I45
Mc Mc
(3)
(1)
(3)
I44
(2)
(1)
I45
I45
Mc Mc
(4)
t
(2)
I45
Mc
(5)
(4)
t
8 RUNNING A PROGRAM
8.7 Interrupt Program
8
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