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FX Series Programmable Controllers Basic Program Instructions 2
2-15
2.14 Master Control and Reset
Program example:
Basic points to remember:
- After the execution of an MC instruction, the bus line (LD, LDI point) shifts to a point after
the MC instruction. An MCR instruction returns this to the ori
g
inal bus line.
- The MC instruction also includes a nest level pointer N. Nest levels are from the ran
g
e
N0 to N7 (8 points). The top nest level is ‘0’ and the deepest is ‘7’.
- The MCR instruction resets each nest level. When a nest level is reset, it also resets ALL
deeper nest levels. For example, MCR N5 resets nest levels 5 to 7.
- When input X0=ON, all instructions between the MC and the MCR instruction execute.
- When input X0=OFF, none of the instruction between the MC and MCR instruction
execute; this resets all devices except for retentive timers, counters and devices driven
b
y
SET/RST instructions.
- The MC instruction can be used as man
y
times as necessar
y
, b
y
chan
g
in
g
the device
number Y and M. Usin
g
the same device number twice is processed as a double coil
(see section 2.5.2). Nest levels can be duplicated but when the nest level resets, ALL
occurrences of that level reset and not
j
ust the one specified in the local MC.
Mnemonic Function Format Devices Program steps
MC
(Master
Control)
Denotes the start
of a master control
block
Y, M (no special
M coils allowed)
N denotes the
nest level (N0 to
N7)
3
MCR
(Master
Control Reset)
Denotes the end of
a master control
block
N denotes the
nest level (N0 to
N7) to be reset.
2
MC N
MCR N
X0
X1
M100N0MC
X2
N0MCR
M100N0
X
N
M
X
Y
X
Y
N
0
0
100
1
0
2
1
0
LD
MC
SP
LD
OUT
MCR
LD
OUT
0
1
4
5
7
8
6
Note: SP - space key
N - nest level of MC (N0 to N7)
Y1
Y0