774
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
34 SFC Program and Step Ladder
34.2 Step Ladder
5. Composition of branches and recombination
When a recombination line is directly connected to a branch line (not by way of a state relay as shown below),
it is recommended to provide a dummy state relay between the lines.
Create step ladder programs as shown below.
1) Selective recombination and selective branch
2) Parallel recombination and parallel branch
3) Selective recombination and parallel branch
STL
LD
SET
STL
LD
SET
STL
LD
SET
LD
SET
100
20
1
X000
X000
TRAN
2
X001
STL
S20
SET
S100
S20
X000
S100
S30
X001
S100
S100
X003
S50
X004
S60
30
3
50
60
X001
TRAN
X003
TRAN
4
X004
TRAN
Dummy state
SET
S100
STL
S30
X003
SET
S50
STL
S100
X004
SET
S60
<Step ladder>
<SFC program>
<List program>
STL
STL
LD
SET
STL
LD
SET
SET
101
20
1
X000
X000
TRAN
S101
STL
S20
SET
S50
S20
S30
X000
S101
S101
S101
S50
S60
30
2
50
60
S101
TRAN
SET
S101
STL
S101
STL
S30
SET
S60
<Step ladder>
<SFC program>
<List program>
Dummy state
STL
LD
SET
STL
LD
SET
STL
LD
SET
SET
102
20
1
X000
S102
TRAN
2
X001
STL
S20
SET
S102
S20
X000
S102
S30
X001
S102
S102
S102
S40
S50
30
3
40
50
X001
TRAN
X102
TRAN
SET
S102
STL
S30
S102
SET
S40
STL
S102
SET
S50
<Step ladder>
<SFC program>
<List program>
Dummy state