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1 PROGRAM EXECUTION
1.5 Program Type
■If an interrupt cause with the same or a lower priority occurs while the interrupt program is
being executed
• For I0 to I23 and I50 to I177
The occurred interrupt cause is memorized, and the interrupt program corresponding to the factor will be executed after the
running interrupt program finishes. Even if the same interrupt factor occurs multiple times, it will be memorized only once.
• For I28 to I31
The interrupt cause that occured is memorized, and the interrupt program corresponding to the cause will be executed after
the running interrupt program finishes. If the same interrupt cause 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 23 Fixed scan
execution mode)
When "Execution Count Takes Priority" is enabled, the interrupt program corresponding to the memorized interrupt causes will
be executed after the running interrupt program finishes. When "Precede Fixed Scan" is enabled, the second and later
occurrences will not be memorized.
I0
Time
Main routine program
I0 interrupt program
I50 interrupt program
I80 interrupt program
I100 interrupt program
I100 I80 I50 I100 I80 I50
The second interruption cause and later causes
that occur during the execution of an interruption
are not memorized.
After the interruption being
executed is completed, the
interruptions are executed
from I0, which has higher
priority level. I50, which
has higher priority rank, is
executed ahead of I80,
which has the same
priority.
I80 is executed.
(I50 is not executed for
the second time.)
I100 is executed.
(I80 is not executed for
the second time.)
Higher
Lower
Priority
rank
I31
Time
Main routine program
Higher
Lower
I31 interrupt program
*
* The priority is the same.
I29 interrupt program
*
I28 interrupt program
*
I28 I29 I28
When "Execution Count
Takes Priority" is set
When "Precede Fixed
Scan" is set
B
A
I29
TO A
TO B
The second and following interruption causes,
which occur while an interruption is executed,
operate according to the setting of the fixed scan
execution mode.
After the interruption being
executed is completed,
I29, which has higher
priority, is executed.
The second
interruption is
not executed.
The second
interruption
is executed.
The second
interruption is
executed.
Priority
rank