Mitsubishi Electric MELSEC-Q00U(J)CPU User Manual

119
CHAPTER 3 FUNCTIONS
3
3.2 Constant Scan
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. ( Page 441, Appendix
1.2.4)
When not executing the constant scan function, leave the constant scan time setting box blank.
END
5ms
0 END 0 END 0 END 0
6ms
5ms
Sequence program
END processing
END
5ms
0
END
0
2ms 6ms
END
0
1ms
5ms
END
0
2ms
7ms7ms 7ms
Sequence program
END processing
Waiting time
8ms 2ms
10ms
9ms
1ms
10ms
Sequence program A
Sequence program B
Sequence program C
END processing
Waiting time
Enter a value.

Mitsubishi Electric MELSEC-Q00U(J)CPU Specifications

General

Brand	Mitsubishi Electric
Model	MELSEC-Q00U(J)CPU
Category	Controller
Language	English