Two proximity sensors can also be installed under the wire rope headboard in the machine room. Generally, the headboard is connected with the load-bearing beam through springs, and the different load of the car corresponds to the different distances between the headboard and the load-bearing beam. By reasonably adjusting the distance between the two proximity sensors and the headboard, one of them can be used as a full load signal and the other as an overload signal.

The output of the proximity sensor is a switch value, some are open collector's and some are passive contacts, which do not need other signal conditioning and are more suitable for the input of PLC.