Automating Manufacturing Systems - Process Control and ...

plc il - 18.5
Ladder
A
X
Instruction List (IL)
LD A
ST X
A X LDN A
ST X
A B
X LD A
LD B
ANB
ST X
A B
X LD A
LDN B
ANB
ST X
A C X LD A
LD B
ORB
B
LD C
ANB
ST X
A B
X LD A
LD B
LD C
C
ORB
ANB
ST X
A C
X LD A
LD B
B D
ORB
LD C
LD D
ORB
ANB
ST X
LD A
AND B
ST X
LD A
ANDN B
ST X
LD A
OR B
AND C
ST X
LD A
LD B
OR C
ANB
ST X
LD A
OR B
LD C
OR D
ANB
ST X
Figure 18.4
IL Equivalents for Ladder Logic
Figure 18.5 shows the IL programs that are generated when there are multiple outputs.
This often requires that the stack be used to preserve values that would be lost nor-