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1  RUNNING A PROGRAM
1.7  Interrupt Program
 • 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.
(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) After the interrupt in execution is completed, interrupts are executed in order from I29 because it has a higher priority.
(4) The second interrupt is executed.
(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) After the interrupt in execution is completed, interrupts are executed in order from I29 because it has a higher priority.
(4) The second interrupt is executed.
I49
I28
I28
(2)
(4)
t
(1)
(3)
High
Low
Main routine program
I49 interrupt program
I28 interrupt program
When interrupts with lower priority level than the one being executed occur
When "Execution Count Takes 
Priority" is set
When "Fixed Scan Takes 
Priority" is set
Priority level of 
interrupt
I31
I29I28
I29I28
B
A
×
t
(4)
(4)
(1)
(2)
(3)
When interrupts with the same priority level as the one being executed occur
Main routine program
I31 interrupt program
I29 interrupt program
I28 interrupt program
Priority level of interrupt:
I31 = I29 = I28
When "Fixed Scan Takes 
Priority" is set
High
Low
Priority level of 
interrupt
From A From B
When "Execution Count Takes 
Priority" is set