Constant Scan - Mitsubishi Q00JCPU User Manual

6
FUNCTIONS

6.2 Constant scan

(1) Definition of Constant Scan
(2) Applications of constant scan
Scan time when constant scan is not used
Scan time when constant scan setting is set to 7 ms
Scan time when constant scan is set to 10 ms during multiple program execution
Basic
Note6.1
Note1
Basic Since the Basic model QCPU cannot execute multiple programs, it is not necessary to be
conscious of the scan time taken for execution of multiple programs.
Note6.1
The scan time differs because the processing time differs depending on whether the
instruction, which is used in the sequence program, is executed or not.
Constant scan is a function to execute the sequence program repeatedly while
maintaining the scan time at a constant time.
I/O refresh is performed before sequence program execution.
Using the constant scan function, the I/O refresh intervals can be made constant if the
sequence program execution time
END 0
END 0 END
Waiting time
5ms
7ms
Figure 6.1 Constant scan operation
varies.Note1
Sequence program
END processing
END 0 END 0
5ms 6ms
Sequence program
END processing
0 END
2ms 6ms 1ms
7ms
Sequence program A
Sequence program B
Sequence program C
END processing
Waiting time
8ms 2ms
10ms
END 0
5ms
0 END 0
5ms 2ms
7ms
Note6.1
9ms 1ms
10ms
6.2 Constant scan
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