Safe set circuit for a safety-oriented RS memory

摘要

The invention concerns a safe set circuit for a safety-oriented RS memory, of which the R input is fed from the output of a non-equivalence comparator, the set input is connected both to its own feedback path and to a constant voltage source, and the output supplies a status signal. So that such memories can be set safely even without the help of safe computers, according to the invention it is proposed that the status signal (STATUS) also feeds, directly or indirectly, a relay (X) with positively guided contacts, of which a first normally-open contact, in series with an off key (T), connects the DC voltage source (+UB) to the relay (X), a second normally-open contact is located in the output (B) of the linked data and status signals, and a normally-closed contact is placed in the connection between the DC voltage source (+UB) and the set input (S) of the RS memory. <IMAGE>