Constant Scan - Mitsubishi Electric Q01UCPU User Manual

3.2

Constant Scan

Scan time differs depending on the execution status of instructions used in sequence programs. This function
repeatedly executes sequence programs keeping their scan time constant.
(1) Application
I/O refresh is performed before every sequence program execution.
This function is used to maintain I/O refresh intervals constant even if the execution time of each sequence
program differs.
• Scan time without constant scan setting
• Scan time with constant scan setting (7ms)
• Scan time for multiple programs with constant scan setting (10ms)
(2) Constant scan time setting
Set a constant scan time value in the PLC RAS tab of the PLC parameter dialog box.
1.2.4)
When not executing the constant scan function, leave the constant scan time setting box blank.
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END 0 END
5ms
Sequence program
END processing
END 0 END
Waiting time
5ms 2ms
7ms
Waiting time
8ms
10ms
Enter a value.
Sequence program
END processing
0 END 0
6ms 5ms
0 END 0
6ms 1ms
7ms
Sequence program A
Sequence program B
Sequence program C
END processing
2ms 9ms
10ms
END 0
END 0
5ms 2ms
7ms
1ms
( Page 439, Appendix