Abstract: A multiplex wiring system having a plurality of communication modules which are interconnected on a pair of buses. Data is transmitted from any one of the modules on one of the buses while redundant or complementary data is transmitted on the other bus. Each module includes three receiving channels, one channel for receiving data, one channel for receiving complementary data, and a differential channel for differentially combining the data and complementary data thereby reducing received noise. A predetermined data sequence is detected on each of the three channels such that specific types of system faults are indicated. In response to the fault indication, the most suitable of the three channels is selected to receive data.

Abstract: A data transfer communication system capable of handling both node-to-node data transfer messages originating at any transmitter and transmitted to a specific receiver on the network and functional command messages originating at any transmitter and broadcast transmitted to an unspecified number of receivers on the network. Receivers are programmed to receive and acknowledge receipt of correspondingly addressed node-to-node type messages and certain correspondingly addressed functional command type messages with their unique addresses in a predetermined field location of the transmitted message. By utilizing pulse width modulation techniques, binary logic signals and a unique start signal are defined and have a dominant hierarchy that allows for bit-wise contention of the common data bus. In that manner, when contention of the data bus is resolved a higher priority message continues to be transmitted while losing contender delays its transmission until after the higher priority message is completed.

Abstract: A filament lamp outage indicator system in which the actuation of an on/off switch to its on position is sensed to enable a logic circuit in the event a current flow increase is not inductively detected in a conductor in series with the switch and a corresponding filament lamp.

Abstract: A microprocessor circuit employed to control the on/off switching of a filament lamp in series with a power switching device and a single conductor is programmed to periodically cycle the filament lamp between its deenergized and energized state at a rate above that which would be humanly perceptible. A toroidal ferrite core surrounds the conductor between the lamp filament and the switch and picks up current changes which occur due to the cycling. The absence of current changes during cycling are perceived by the microprocessor as a lamp failure and appropriate signaling is made to indicate the lamp failure.