Mitsubishi MELSEC QCPU Programming Manual page 92

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