100
Computing the Cycle Time Section 2-7
been executed. The length of the interrupt response time for I/O interrupt
tasks depends on the following conditions.
Note (1) The wait time occurs when there is competition with other interrupts. As
a guideline, the wait time will be 3 to 153 µs.
(2) I/O interrupt tasks can be executed during execution of the user program
(even while an instruction is being executed by stopping the execution of
an instruction), I/O refresh, peripheral servicing, or overseeing. The inter-
rupt response time is not affected by which of the above processing op-
erations during which the interrupt inputs turns ON. I/O interrupts,
however, are not executed during execution of other interrupt tasks even
if the I/O interrupt conditions are satisfied. Instead, the I/O interrupts are
executed in order of priority after the current interrupt task has completed
execution and the software interrupt response time has elapsed.
The interrupt response time of input interrupt tasks is calculated as follows:
Interrupt response time = Input ON delay + Software interrupt response time
Scheduled Interrupt Tasks The interrupt response time of scheduled interrupt tasks is the time taken
from after the scheduled time specified by the MSKS(690) instruction has
elapsed until the interrupt task has actually been executed. The length of the
interrupt response time for scheduled interrupt tasks is 1 ms max. There is
also an error of 80 µs in the time to the first scheduled interrupt (0.5 ms min.).
Note (1) Scheduled interrupt tasks can be executed during execution of the user
program (even while an instruction is being executed by stopping the ex-
ecution of an instruction), I/O refresh, peripheral servicing, or overseeing.
The interrupt response time is not affected by which of the above pro-
cessing operations during which the scheduled interrupt time occurs.
Scheduled interrupts, however, are not executed during execution of oth-
er interrupt tasks even if the interrupt conditions are satisfied. Instead, the
interrupts are executed in order of priority after the current interrupt task
has completed execution and the software interrupt response time has
elapsed.
Item Interrupt response time Counter interrupts
Hardware response Rise time: 50 µs ---
Fall time: 50 µs ---
Software interrupt
response
Minimum: 98 µs Minimum: 187 µs
Maximum: 198 µs + Wait
time (See note 1.)
Maximum: 287 µs + Wait time
(See note1.)
Input
(Interrupt signal retrieval)
Interrupt task execution
Software interrupt response time
Input ON delay
Cyclic task execution
(main program)
Ladder program
execution time
Next interrupt signal
can be accepted.
The time from completing the ladder program in the input
interrupt task until returning to cyclic task execution is 60 µs.
Input interrupt task
response time
Return time from
input interrupt task
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