Hysteresis - Siemens S7-300 Operating Instructions Manual

Cam control basics

3.3 Hysteresis

3.3 Hysteresis
Definition
Mechanical imbalance at the axis may cause fluctuation of the actual position value. If the
actual position value is offset by one edge of a cam, or within an active cam with only one
effective direction, this cam's activation would be cycled on and off continuously. A
hysteresis prevents this flutter.
A hysteresis setting is dependent on the actual value, and applies globally to all cams. It is
enabled when a direction reversal is detected. A hysteresis will always take effect,
regardless of whether or not a cam is set at the current axis position.
Rules for the hysteresis range
Rules applicable to the hysteresis range:
● The hysteresis will always be set when a directional reversal is detected.
● The indication of the actual value remains constant within the hysteresis.
● The direction is not redefined within the hysteresis.
● A position-based cam is neither activated nor deactivated within the hysteresis.
● A time-based cam is not activated within the hysteresis. An active time-based cam is
● When the value is out of the hysteresis range, the FM 352 sets:
● The hysteresis range applies to all cams.
22
deactivated on expiration of the assigned activation (not only on reaching the hysteresis
limit).
– the actual position value
– the current direction of motion of the axis
– the current states of all cams
FM 352 electronic cam controller
Operating Instructions, 05/2011, A5E01071724-03