Mitsubishi L02CPU, User Manual, Page: 82 / 340

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3.2
Constant Scan
Scan time of the CPU module is not constant because the processing time varies depending on the execution status of
instructions used in a program. By using this function, scan time can be maintained constant.
(1) Application
I/O refresh is performed before program execution. By using this function, the constant I/O refresh intervals can
be maintained even the time required for program execution changes.
• 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
The setting range is from 0.5 to 2000ms (in increments of 0.5ms).
When not using the constant scan function, leave the setting box blank.
Project window [Parameter] [PLC Parameter] [PLC RAS]
The constant scan accuracy is 0.01ms. However, constant scan time may increase when an interrupt program or
a fixed scan execution type program is being executed.
END
5ms
0 END 0 END 0 END 0
6ms 5ms
Program execution
END processing
END
5ms
0 END 0
2ms 6ms
END 0
1ms 5ms
END 0
2ms
7ms 7ms 7ms
Program execution
END processing
Waiting time
8ms 2ms
10ms
9ms 1ms
10ms
Execution of program A
Execution of program B
Execution of program C
END processing
Waiting time
Enter a value.