Siemens SIMATIC S7-200 - Counter Examples; Example of CTD Counter Instruction for SIMATIC LAD, FBD, and STL

SIMATIC Instructions
9-25
S7-200 Programmable Controller System Manual
A5E00066097-02
Counter Examples
I1.0
Load
LD I3.0 //Count Down Input
LD I1.0 //Load Input
CTD C50, 3
Timing Diagram
LAD
STL
I3.0
Down
I3.0
C50
I1.0
CTD
LD
CD
PV
0
1
2
3
3
C50
(current)
C50
(bit)
C50
+3
I3.0
I1.0
3
CD
PV
LD
FBD
CTD
2
0
Figure 9-8 Example of CTD Counter Instruction for SIMATIC LAD, FBD, and STL