Siemens Simatic S7 Series

Program instructions
7.6 Counters
S7-200 SMART
System Manual, 09/2015, A5E03822230-AC
219
Example CTUD count up/down
LAD
STL
I0.0 counts up
I0.1 counts down
I0.2 resets current value to 0
Network 1
LD I0.0
LD I0.1
LD I0.2
CTUD C48, +4
Count Up/Down counter C48 turns on
C48 bit when current value >= 4
Network 2
LD C48
= Q0.0
Timing diagram