Siemens SIMATIC ET 200S Operating Instructions Manual page 134

1Count5V
3.6 Count Modes
The internal gate is automatically closed in the event of an overflow/underflow at the count
limits. To restart counting, you have to open the gate again.
Figure 3-3
With an interrupting gate function, the counter status remains at the underflow when the gate
is started.
Figure 3-4
134
Count Once Without Main Count Direction; Canceling Gate Function
Count Once with Up as the Main Count Direction
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07