Method and electrical circuit for the reliable detection of process states within freely couplable units

An arrangement for monitoring states of processes within each of a plurality of freely couplable units, comprising:

• pluralities of internal signal current loops, internal to respective ones of the units, each loop internal to one of the units being associated with a respective one of the processes and including a controllable current source and at least associated current detectors and series connected switches actuated by the respective process;
• means for opening said internal signal current loops when the units are coupled together and forming closed common signal current loops associated with a respective one of the processes and passing through all of the coupled units, said common loops each having the series connected switches and the current sources therein, and having the current detectors therein so as to be actuated by the associated process;
• a plurality of subloops, each subloop corresponding to one of said controllable current sources and bridging the current source and associated current detectors, each subloop having source and associated current detectors, each subloop having switch means for actuating the subloop so that the subloop current in the subloop is defined by the respective current source;
• and
• means for monitoring the switch means, said monitoring means including means, having additional position specific current loops, for monitoring said switch means by predetermined tests employing said additional, position specific current loops.

A method of performing tests on an arrangement for monitoring states of processes within each of a plurality of freely couplable units, the arrangement comprising pluralities of internal signal current loops, internal to respective ones of the units, each loop internal to one of the units being associated with a respective one of the processes and including a controllable current source and at least associated current detectors and series connected switches actuated by the respective process;

• means for opening said internal signal current loop when the units are coupled and forming closed common signal current loops associated with a respective one of the processes and passing through all of the coupled units, the common loops each having the series connected switches and the current sources therein, and having the current detectors therein so as to be actuated by the associated process;
• a plurality of subloops, each subloop corresponding to one of the controllable current sources and bridging the current source and associated current detectors, each subloop having switch means for actuating the subloop so that the subloop current in the subloop is defined by the respective current source;
• and means for monitoring the switch means, the monitoring means including means, having additional, position specific current loops, for monitoring the switch means by predetermined tests employing said additional, position specific current loops, the method comprising the steps of:
• performing the predetermined tests on-line with respect to specific subloops during process compilation of associated processes;
• and
• while performing the predetermined tests, feeding a fixed continuous logic signal to the current sources so that the current sources provide current to the respective subloops, and supplying the two additional current loops with clock pulses in dynamically alternating sequences of logic 1's and 0's which must be recognized, from two alternating working non-failsafe outputs of the computer.