The controller has a detection unit contg. at least one transmitter and receiver operating with timer controlled infrared radiation to detect the presence of an object in the detection region by reflected radiation converted into pulses. A reflector card (2) used to set up the controller has at least one high grade infrared reflective surface(22). When a defined reflected radiation intensity level is exceeded the controller is automatically switched over from the operating mode to the programming or learning mode and back again.
