What is AntiSwitch and how does it work?
AntiSwitch is a current-sensing automatic stop function. When the motor reaches the mechanical stop at the end of travel, the current it draws rises; the module detects this rise and cuts the motion in that direction. On the KS250 it is built in; on the PT500 the independent threshold for each direction of rotation is set with the A1 and A2 pots.
When a brushed DC motor stalls against a mechanical stop, the rotor stops, the back EMF disappears and the motor behaves almost like a short-circuit load. The current drawn rises noticeably at that moment. AntiSwitch measures exactly this current jump and cuts the output in the relevant direction when the preset threshold is exceeded.
The practical result is this: no external limit switch and limit wiring are needed to define the travel limit. This considerably simplifies the wiring, especially in applications such as doors, barriers, shutters and actuators whose end point is mechanically definite.
- KS250: AntiSwitch is built in.
- PT500: AntiSwitch is built in and there are independent current limits for the clockwise and reverse directions. The A1 pot sets the clockwise limit and the A2 pot the reverse limit. This lets you calibrate each direction separately when the load in the two directions differs (for example lifting up versus lowering down).
Two conditions are required for it to work correctly: the mechanics must withstand the stall force for the duration of detection, and there must be a distinguishable difference between the normal operating current and the stall current.
Full topic: DC Motor Driver Selection Guide