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MELSEC-Q
4 SEQUENCE PROGRAM CONFIGURATION AND EXECUTION
CONDITIONS
(4) Precautions for creating Low speed execution type programs
(a) See Section 10.6.1 for details on index register processing when switching
from a scan execution type program to a low speed execution type
program.
(b) See Section 10.6.2 for details on index register processing when an
interrupt program/a fixed scan execution type program is executed during
execution of low speed execution type program.
(c) The low speed program execution time should be set so that sum of the
[scan time] + [low speed program execution time] sum is less than the WDT
setting value.
(d) The COM instruction can not be used in low speed execution type
programs.
(e) Low speed execution type programs can also be executed with scans that
execute the initial execution type programs.
Establish an interlock with SM402 and SM403 for the circuit that validates
the low speed execution type program's operation after the scan execution
type program has been executed.
(f) When the "constant scan time" and "low speed program execution time"
have been set, "PRO. TIME OVER (error code: 5010)" will occur if (surplus
time of constant scan) < (low speed program execution time).
(5) Low speed END processing
The low speed END processing is performed when all the low speed execution
type programs are executed.
The following processing is performed for the low speed END processing.
• Low speed program special relay/special register setting
• Low speed execution type program write during RUN
• Low speed scan time measurement
• Low speed execution type program watch dog timer reset
When the low speed END processing is completed, the low speed execution type
program is executed from the beginning again.
POINT
(1) During execution of low speed execution type programs, the constant scan
time may deviate by the amount of "the maximum instruction processing time +
low speed END processing time".
(6) Low speed scan time
(a) The low speed scan time is the total time required for low speed execution
type program execution and low speed END processing.
If multiple low speed execution type programs are executed, the low speed
scan time is the total time required to execute all the programs, plus the low
speed END processing time.
When an interrupt program/fixed scan execution type program is executed,
the value added with the interrupt program/fixed scan execution type
program's execution time will become the low speed scan time.