AUTOMATIC SENSOR IDENTIFICATION FOR ULTRASONIC PROXIMITY SWITCHES

摘要

In the case of ultrasonic proximity switch systems having separate evaluation electronics and varying sensor designs, the evaluation parameters must usually be adapted to the particular sensor type. To avoid errors relating to this, it is advantageous when the system is switched over automatically when a new sensor type is connected. Previously, sensor identification has been realized through manual coding or by coupling different voltage levels to a sensor output signal. The aim is to reduce the susceptibility to faults and the expenditure entailed by this method by applying a plurality of sensors. This is achieved in that the oscillator frequency corresponding to the sensor type is indicated with the help of a counter by means of a pulse-width modulated signal, which corresponds to the pulses of the oscillator frequency that are counted according to the counter content. This counter is advantageously accommodated in an integrated circuit, with which a pulse-width modulated signal is already generated as temperature information.