Omron SYSMAC C20K Operation Manual page 50

The Ladder Diagram
0006 0007 0003
0005
0001
Block a
0000 0001
LD 0000
AND 0001
0500
OR
0002
AND
AND NOT 0003
38
Again, this diagram can be redrawn as follows to simplify program structure
and coding and to save memory space.
0004 0000
0002
Our last example may at first appear very complicated but can be coded us-
ing only two logic block instructions. The diagram appears as follows:
0000
0100
0500
The first logic block instruction is used to combine the execution conditions
resulting from blocks a and b, and the second one is used to combine the
execution condition of block c with the execution condition resulting from the
normally closed condition assigned 0003. The rest of the diagram can be
coded with ladder instructions. The logical flow for this and the resulting code
are shown below.
Block b
0100 0101
LD 0100
AND 0101
OR LD
LD
0500
AND
0003
0002
OR
AND LD
0105
Address Instruction
0105
0000
0001
0002
0003
0004
0005
0006
0007
0008
0009
Block a
0001 0002 0003
0101
Block b
Block c
0004 0005
Address Instruction
0000
0004
0001
0005
0002
0006
0003
0004
0006
0005
0006
0007
0008
0009
0010
0011
0012
Section 4-3
Operands
LD
AND
OR
AND
AND
LD
AND
OR LD
AND
OUT
0004 0005
0105
0006
Block c
Operands
LD
AND
LD
AND
OR LD
OR
AND
AND NOT
LD
AND
OR
AND LD
OUT
0006
0007
0005
0003
0004
0001
0002
---
0000
0105
0000
0001
0100
0101
---
0500
0002
0003
0004
0005
0006
---
0105