Mitsubishi MELSEC-A Series Programming Manual page 101

5. SEQUENCE INSTRUCTIONS
[Ladder as displayed in the GPP ladder mode]
A
N0 M15
B
N1 M16
C
N2 M17
[Ladder as displayed in the GPP ladder mode]
A
N1 M15
B
N0 M16
Nesting numbers for MCR are
reverse.
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.
MC N0 M15
( )
MC N1 M16
( )
MC N2 M17
)
(
MCR N2
( )
MCR N1
( )
MCR N0
( )
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.
MC N1 M15
( )
MC N0 M16
( )
MCR N1
( )
MCR N0
( )
[Ladder as it actually operates]
[Ladder as it actually operates]
Not a normal MC circuit since bus lines
are crossing.
5 − 32
MELSEC-A
Executed
when A is
ON.
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.