Mitsubishi MELSEC-A series Programming Manual

5. SEQUENCE INSTRUCTIONS
5 − 32
MELSEC-A
The MC instructions can be used by nesting. Range of each MC instruction is
identified by a nesting number. Nesting numbers are used in the range of N0 to N7.
Using nesting, circuits which sequentially restrict execution conditions of a program
can be made.
The diagrams below show an example of circuit which uses nesting.
Cautions when Using Nesting Architecture
(1) Nesting is available in 8 levels from N0 to N7. Nest MC starting with lower
nesting numbers (N) and MCR with higher numbers. If the nesting numbers are
used reverse, nesting is not configured and the PC does not operate correctly.
()
()
(
)
(
)
()
()
[Ladder as displayed in the GPP ladder mode]
[Ladder as it actually operates]
Executed
when A is
ON.
A
N0 M15
MC N0 M15
Executed
when A
and B are
ON.
Executed
when A, B
and C are
ON.
Executed
when A
and B are
ON.
Executed
when A is
ON.
No relation
with A, B
and C.
B
N1 M16
MC N1 M16
C
N2 M17
MC N2 M17
MCR N2
MCR N1
MCR N0
()
()
()
()
[Ladder as displayed in the GPP ladder mode]
[Ladder as it actually operates]
A
N1 M15
MC N1 M15
B
N0 M16
MC N0 M16
MCR N1
MCR N0
Nesting numbers for MCR are
reverse.
Not a normal MC circuit since bus lines
are crossing.

Mitsubishi MELSEC-A series Specifications

General

Brand	Mitsubishi
Model	MELSEC-A series
Category	Controller
Language	English