Abstract: A method and system for monitoring the condition of a plurality of electrical devices, particularly electrical switches actuated by sensors, to determine the condition of each and the location of e.g., a malfunctioning device. The electrical devices are connected in parallel across a pair of line conductors. A voltage-dropping element is inserted in series with the line at the input side of each device, and a current-limiting element, passing a fixed current independently of voltage above a predetermined threshold, is inserted in series with the respective device. Initially, a voltage is applied to the line of greater magnitude than the sum of the predetermined threshold and the voltage of the first device, and is sequentially increased in a plurality of steps, while the current passing through the line initially and after each of the voltage steps is measured.

Abstract: System and method for controlling the transfer of data between a plurality of processors in a network. Synchronization between the processors is effected by means of asynchronously operated address counters which control the transmission of data from the processors. When a transmission occurs, the address counters are all set to a count corresponding to the address of the transmitting station, and in the event of a transmission from more than one processor, the address counters are reset to an initializing level. A station is permitted to transmit only when the count in its address counter corresponds to the address of the station.