Siemens Simatic S7-200 System Manual page 285

The convergence of control streams can be implemented in an SCR program by making the
transition from state L to state L' and by making the transition from state M to state M'. When
both SCR bits representing L' and M' are true, state N can the enabled as shown below.
Network
Network
. . .
Network
V100.5
Network
Network
Network
. . .
Network
C50
Network
Network
S3.5
Figure 10-43
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
LAD
S3.4
Beginning of State L
SCR
control region
S3.5
Transition to State L'
SCRT
End of SCR region for
SCRE
State L
S6.4
Beginning of State M
SCR
control region
S6.5
Transition to State M'
SCRT
End of SCR region for
SCRE
State M
S6.5
S5.0
Enable State N
S
1
S3.5
Reset State L'
R
1
S6.5
Reset State M'
R
1
Example of Convergence of Control Streams
Instruction Set
STL
Network
LSCR S3.4
Network
. . .
Network
LD V100.5
SCRT S3.5
Network
SCRE
Network
LSCR S6.4
Network
. . .
Network
LD C50
SCRT S6.5
Network
SCRE
Network
LD S3.5
A S6.5
S S5.0, 1
R S3.5, 1
R S6.5, 1
10-97