The wms- ultrasonic sensors are equipped with an echo signal output. The user is responsible for providing a signal and reading the data. In contrast to the standard ultrasonic sensors, the wms- sensors are not equipped with a microprocessor. This makes the wms- a costs saving solution. The signal input of the sensor has to be connected momentary with -Ub through an open-collector circuit via the operating system of the customer. Then, the echo signal output sends out all received echo signals depending on their duration as 1 bit values (echo yes/no). This takes 8 to 65 ms, depending on the type of sensor. The calculation of the distance and the processing of the signal that follows are both carried out in the operating system of the customer.