Specifications

SIMATIC Instructions
9-155
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
SCR Example
Figure 9-58 shows an example of the operation of SCRs.
 In this example, the first scan bit SM0.1 is used to set S0.1, which will be the
active State 1 on the first scan.
 After a 2-second delay, T37 causes a transition to State 2. This transition
deactivates the State 1 SCR (S0.1) segment and activates the State 2 SCR
(S0.2) segment.
SCRT
SCR
S0.2
S0.1
SCRE
S
Q0.4
R
Q0.5
LAD STL
Network 1
LD SM0.1
S S0.1, 1
Network 2
LSCR S0.1
Network 3
LD SM0.0
S Q0.4, 1
R Q0.5, 2
TON T37, 20
Network 1
Network 3
Network 4
Network 5
On the first scan,
enable State 1.
S
S0.1SM0.1
1
SM0.0
1
2
TON
IN
PT
T37
20
Beginning of State 1
control region
Turn on the red light on
First Street.
Turn off the yellow and
green lights on First
Street.
Start a 2-second timer.
Transition to State 2
after a 2-second delay.
End of SCR region for
State 1
T37
Network 2
Network 4
LD T37
SCRT S0.2
Network 5
SCRE
(Program continued on next page)
Figure 9-58 Example of Sequence Control Relays (SCRs)