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MELSEC-Q/QnA
5 SEQUENCE INSTRUCTIONS
REMARK
: When programming in the ladder mode of a peripheral device, it is not necessary to input
contacts on the vertical bus.
These will be automatically displayed when the "conversion" operation is conducted after the
creation of the ladder and then “read” mode is set.
MC
(1) If the ON/OFF command of the MC instruction is ON when master control is commenced, the
operation result between the MC instruction and MCR instruction will be exactly as the
instruction (ladder) shows.
If the MC ON/OFF indicator is OFF, the operation result between the MC and MCR
instructions will be as shown below:
Device Device Status
High speed timer
Low speed timer
Count value goes to 0, coils and contacts all go OFF
High speed retentive timer
Low speed retentive timer
Counter
Coils go OFF, but counter values and contacts all
maintain current status.
Devices in OUT instruction All turned OFF
SET, RST
SFT
Basic, Application
Devices in the
following instructions:
Maintain current status
(2) Even when the MC instruction is OFF, instructions from the MC instruction to the MCR
instruction will be executed, so scan time will not be shortened.
POINT
If there are unnecessary contact instructions (FOR - NEXT, EI, DI, etc.) in ladders which use
master controls, the CPU module will execute these instructions regardless of the ON/OFF
state of the MC instruction.
(3) By changing the device designated by
D
, the MC instruction can use the same nesting (N)
number as often as desired.
(4) Coils from devices designated by
D
are turned ON when the MC instruction is ON.
Further, using these same devices with the OUT instruction or other instructions will cause
them to become double coils, so devices designated by
D
should not be used within other
instructions.
MCR
(1) This is the instruction for recovery from the master control, and indicates the end of the master
control range of operation.
(2) Do not place contact instructions before the MCR instruction.
[Operation Errors]
(1) There are no operation errors associated with the MC or MCR instructions.
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