Mitsubishi MELSEC-A series, Programming Manual

Page: 61 / 508

3. INSTRUCTION STRUCTURE
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MELSEC-A
3.9 Operation when the OUT Instruction, SET/RST Instruction and PLS/PLF Instruction are from the
Same Device
Here, operation in the case that there is multiple execution of the OUT instruction,
SET/RST instruction and PLS/PLF instruction during 1 scan using the same device.
(1) In the case of the OUT instruction from the same device.
Do not carry out execution of the OUT instruction multiple times during 1 scan
from the same device.
If execution of the OUT instruction multiple times during 1 scan from the same
device is attempted, the specified device is turned On/Off in accordance with the
calculation results up until the time the OUT command was executed, and this is
done for each OUT instruction that is executed.
Since the specified device is turned On or Off when each OUT instruction is
executed, it results in the device being switched On and Off repeatedly during 1
scan operation.
Operation in the case of a circuit for switching the same internal relay (M0) On
and Off by inputs X0 and X1 being created is shown in the following figure.
[Circuit]
M0
X0
M0
X1
[Timing Chart]
M0
M0
M0
M0
M0 goes On because X0 is On.
M0 goes Off because X1 is Off.
M0 remains Off because X0 is Off.
M0 goes On because
X1 is On.
OFF
ON
ON
OFF
ON
END END END
X0
X1
M0
X0 X0
X1 X1
OFF
In the case of a refresh type CPU module, if output (Y) is specified by the OUT
instruction, the On/Off state of the last Out instruction to be executed during 1 scan
operation is output.