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MELSEC-Q
4 SEQUENCE PROGRAM CONFIGURATION AND EXECUTION
CONDITIONS
1 If a constant scan time has been designated, the low speed execution
type program will be executed repeatedly during the constant scan's
surplus time.
Therefore, the low speed execution type program's execution time
varies from scan to scan.
As the low speed execution type program will not be executed at all if
the constant scan's surplus time is 0.5 ms or less, a constant scan time
setting should be designated which provides a surplus time of more
than 0.5 ms.
2 If a low speed program execution time has been designated, the low
speed execution type program will be executed repeatedly in
accordance with that time setting.
Therefore, the scan time will vary from scan to scan.
3 If a constant scan time has been designated, the surplus time after
completion of low speed END processing is waiting time, and execution
of a scan execution type program starts when the constant scan time
has elapsed.
This means that the scan time is constant in each scan.
However, if the surplus time after the constant scan is less than 0.5 ms,
low speed execution type programs cannot be executed. If using a low
speed execution type program, set the constant scan time so that the
surplus time is 0.5 ms or longer.
4 If a "low speed program execution time" has been designated, scan
execution type program operation is started ignoring the surplus time
after completion of low speed END processing.
This means that the scan time differs in each scan.
(b) If a low speed execution type program cannot be processed within constant
scan surplus time or within the low speed program execution time, program
execution is temporarily stopped and the remainder of the program is
executed in the next scan.
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