Siemens SIMATIC ET 200S Operating Instructions Manual page 151

Method of Operation with Counter Status ≤ Comparison Value and Counter Status ≥ Comparison
Value
The diagram below provides an example of how hysteresis works. The figure shows the
various responses of an output with a hysteresis of 0 (= switched off) as opposed to
hysteresis of 3. In the example, the comparison value is 5.
The following settings are assigned for the counter: "Main count direction" = "Up" and
"Switch on at counter status ≥ comparison value".
When the comparison condition is met, hysteresis becomes active. While the hysteresis is
active, the comparison result remains unchanged.
If the count value goes outside the hysteresis range, hysteresis is no longer active. The
comparator switches again according to its comparison conditions.
Figure 3-15
Note
If the count direction changes on the comparison value when hysteresis is active, the output
is reset.
Technological Functions
Operating Instructions, 06/2010, A5E00124867-07
Example of How Hysteresis Works
1Count5V
3.6 Count Modes
151