Siemens SIMATIC ET 200S Operating Instructions Manual page 149

Method of Operation when the Comparison Value Is Reached and the Pulse Duration = 0
The diagram below provides an example of how hysteresis works. The figure shows the
differences in the behavior of an output when hysteresis of 0 (= switched off) is assigned as
opposed to hysteresis of 3. In the example, the comparison value is 5.
The following settings are assigned for the counter: "Pulse on reaching the comparison
value", "No main count direction" and "Pulse duration = 0".
When the comparison conditions are 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hysteresis range, hysteresis is no longer active.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 deletes the result of the
comparison.
Figure 3-16
Method of Operation when the Comparison Value Is Reached, Output Pulse Duration
The diagram below provides an example of how hysteresis works. The figure shows the
differences in the behavior of an output when hysteresis of 0 (= switched off) is assigned as
opposed to hysteresis of 3. In the example, the comparison value is 5.
The following settings are assigned for the counter: "Pulse on reaching the comparison
value", "No main count direction" and "pulse duration > 0".
When the comparison conditions have been met, hysteresis becomes active and a pulse of
the assigned duration is output.
If the count value goes outside the hysteresis range, hysteresis is no longer active.
Technological Functions
Operating Instructions, 02/2007, A5E00124867-05
Example of How Hysteresis Works
1Count5V/500kHz
3.6 Count Modes
149