Control circuit for interrogation of signal sources - has counting stages checked for simultaneous interrogation signals and disconnected at signal presence

摘要

The circuit consists of counting stages connected into a ring counter. Their outputs are connected to the signal sources to be interrogated and also to the inputs of a fault detector which finds whether one or two or more ring counter outputs carry an interrogation signal. When two or more signals are present, a fault is signalled. Outputs of at least two adjacent counting stages of the ring counter are connected to at least one logic element. When two or more interrogation signals are present, at least one switch is operated. Counting stages which have a lower order number than that which causes the operation of one or more switches are disconnected, and omitted during subsequent counting cycles.