Contact-free safety switch, e.g. for controlling a machine, comprises redundant read units that interact with a transponder, such that a release or switching code will only be transmitted if both units authorize a code word

摘要

Contact-free switch comprises two redundant read units, which emit electromagnetic high frequency signals. The signals are received by a transponder in which a code word is stored and answered by transmission back of the code word. Both read units compare the code word with their stored code word value. A switching command signal is only output when both read units confirm the code word value. Optimally the read units use different signal processing programs.