Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual page 76

■If the same interrupt factor occurs while the interrupt program is being executed
• For I0 to I15 and I50 to I1023
The interrupt factor that has occurred is memorized, and the interrupt program corresponding to the factor will be executed
when the interrupt is enabled. Even if the same interrupt factor occurs multiple times, it will be memorized only once.
Main routine program
I0 interrupt program
(1) The second and following interrupt factors that occur while interrupts are executed are not memorized.
(2) After the interrupt in execution is completed, the first interrupt program is executed.
• For I45
If an interrupt factor which is the same as that for the running interrupt program occurs, the factor is not memorized.
Therefore, the corresponding interrupt program will not be executed after the running interrupt program finishes. Also, if the
I45 interrupt program for this cause cannot be executed, SM481 (Cycle overrun flag for multiple CPU synchronization
program (I45)) is turned on, and SD481 (Number of cycle overrun events for multiple CPU synchronization program (I45))
reaches its upper limit.
Main routine program
I45 interrupt program
Mc: Multiple CPU synchronization cycle
(1) The interrupt factor is discarded because the same interrupt (I45) is being executed.
(2) The interrupt is not executed.
(3) The interrupt is executed.
• For I28 to I31, I48, and I49
The interrupt factor that has occurred is memorized. After the running interrupt program finishes, the interrupt program
corresponding to the factor will be executed. If the same interrupt factor occurs multiple times, it will be memorized once but
operation at the second and later occurrences depends on setting of the fixed scan execution mode ( Page 57 Fixed scan
execution mode). When "Execution Count Takes Priority" is enabled, the interrupt program corresponding to the memorized
interrupt factor will be executed after the running interrupt program finishes. When "Precede Fixed Scan" is enabled, the
second and later occurrences will not be memorized.
I31
I31
Main routine program
I31 interrupt program
(1) The second and following interrupt factors that occur while interrupts are being executed operate according to the setting of the fixed scan execution mode.
(2) The program is not executed for the second time.
(3) The second interrupt is executed.
1 RUNNING A PROGRAM
74
1.7 Interrupt Program
I0
I0
I45 I45
Mc
(1)
When "Execution Count Takes Priority" is set
I0
(1)
(2)
I45
Mc
(3)
(2)
t
(1)
I31
When "Fixed Scan Takes Priority" is set
×
(3)
t
(2)
t