Danger alarm system

A danger alarm system comprising:

• a plurality of alarm circuits operable to provide first signals representing a quiescent condition and second signals representing an alarm condition;
• a plurality of signal lines each connected to a respective alarm circuit;
• a plurality of alarm connection circuits each connected to a respective signal line and each having three outputs and each operable to provide a rest signal at a first output in response to a first signal, an alarm signal at a second output in response to a second signal and a malfunction signal at a third output in response to the absence of the first and second signals;
• a memory including a plurality of storage locations each including an input and an output and each assigned to and operable to store the busy and non-busy state of a respective line;
• a plurality of first indicators each connected to said output of a respective storage location and operable in response to a busy state to indicate seizure of the respective line;
• and
• a plurality of synchronously operable multiplex devices, first, second and third ones of said multiplex devices sequentially connected to said alarm connection circuits to read said first, second and third outputs, respectively, of said plurality of alarm connection circuits,
• said memory comprising:
• input means including a fourth one of said multiplex devices sequentially connectible to said inputs of said memory;
• switching means connected between said first and second multiplex devices and said fourth one of said multiplex devices and selectively operable in a first mode to pass said rest and alarm signals as busy state signals to said memory and in a second mode to block the passage of said rest signals to said memory,
• output means including a fifth one of said multiplex devices connected to read the outputs of said memory and connected to said switching means, and
• control means connected to said second and third multiplex devices and to said switching means, including first and second outputs, and operable in response to conjunct busy state and alarm signals to provide the alarm signal at said first output and in response to conjunct busy state and malfunction signals to provide the malfunction signal at said second output.