Mitsubishi MELSEC QCPU User Manual

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MELSEC-Q/QnA
3 CONFIGURATION OF INSTRUCTIONS
(4) PLF instructions using the same device
The PLF instruction turns ON the specified device when the PLF command turns ON from
OFF. It turns OFF the specified device at any other time (OFF
OFF, OFF ON, and ON
ON).
When two or more PLF instructions using the same device are programmed in one scan, each
PLF instruction turns OFF the specified device when the corresponding PLF command turns
OFF from ON and it turns OFF the specified device at any other time.
For this reason, when two or more PLF instructions using the same device are programmed in
one scan, the device that has been turned ON by the PLF command may not turn ON again
throughout the scan.
[Circuit]
M0
X0
X1
PLF
M0
PLF
[Timing Chart]
• The ON/OFF timing of the X0 and X1 is different. (The specified device does not turn ON
throughout the scan.)
M0
OFF
ON
END
END END
X0
X1
M0
OFF
OFF
ON
PLF
X0
X1
M0PLF
M0PLF
M0PLF
X0
X1
M0 turns OFF because X0 is not turning
OFF from ON. (M0 stays OFF.)
M0 turns OFF because X1
turns OFF from ON.
(M0 stays OFF.)
M0 turns ON because X0
turns OFF from ON.
M0 turns OFF because X1 is
not turning OFF from ON.
• The X0 and X1 turn OFF from ON at the same time.
M0
OFF
ON
END
END
END
X0
X1
M0
OFF
OFF
PLF
X0
X1
M0PLF
M0PLF
M0PLF
X0
X1
ON
M0 turns OFF because X0 is not turning
OFF from ON.
M0 turns OFF because X1
is not turning OFF from ON.
(M0 stays OFF.)
M0 turns ON because
X0 turns OFF from ON.
M0 turns ON because X1 turns
OFF from ON. (M0 stays ON.)
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Mitsubishi MELSEC QCPU Specifications

General

Brand	Mitsubishi
Model	MELSEC QCPU
Category	Controller
Language	English