Siemens SIMATIC S7-300 FM 350-1 Manual page 118

Operating Modes, parameters and commands
7.3 Count modes
If the count value overshoots/undershoots the range of the hysteresis (at counter value 2 or
8 in the example) the hysteresis ceases to be active. The comparator switches again
according to its comparison conditions, i.e., in the example at counter value 5.
Figure 7-20
Note
If the counter value is equal to the comparison value, and the hysteresis is active, FM 350-1
resets the output when the count direction changes at the comparison value (see the
diagram below.)
Figure 7-21
118
Example showing the effect of the hysteresis
Example of a hysteresis for a change of direction at the comparison value
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01