Master Control Instructions Master Control Set, Reset (Mc, Mcr) - Mitsubishi MELSEC A1SCPU Handy Manual

Master control instructions
Master control set, reset (MC, MCR)
100
ms,
10
ms
timers
Time value is set to
0
Device number to be turned ON
Nesting number (NO to N7)
- r
+
Device
100 ms retentive OUT instruction SETIRST
timer and counter and SFT
Remains at present All turn OFF Status is
value held
MC
The MC instruction is used to allow the sequence program to perform efficient circuit
switching by opening and closing the common bus circuits. MC is the master control
start instruction, when the ON/OFF command for the MC is ON, operation results from
MC to MCR remain unchanged. Scanning between the MC and MCR instructions is
executed even when the ONlOFF command for the MC instruction is OFF. Scan time
does not therefore become shorter. When the ON/OFF command for the MC
instruction is OFF, the operation result of MC to MCR is as indicated below
The MC instruction can use the same nesting N number repeatedly by changing the
specified device number. When the MC instruction is ON, the coil of the specified
device is turned ON. If a device is used twice for the OUT instruction, it is treated as a
duplicated coil. To avoid this, do not use the specified device in other instructions.
MCR
The MCR instruction is a master control reset, and indicates the end of a master control
range. Do not use a contact instruction before the MCR instruction
The MC instructions can be used by nesting. The range of each MC instruction is
identified by a nesting number. Nesting numbers are used in the range of
N O
to N7.
Using nesting, circuits which sequentially restrict execution conditions of a program can
be made.
An example of a program which uses the nesting of MC instructions is shown on the
following page.
116