In a multiplex signalling system for two-way data transmission over a single transmission line, the line is configured as a loop terminating at each end at a central or control station, thereby furnishing two communication paths between the central station and each of a plurality of remote stations distributed along the line. Transmission of signals from the central station and reception of signals at the control station are duplicated at the line ends so that an open line fault can readily be identified from an analysis of signals received at the central station. Switches at the remote stations operable in accordance with reception of signals along both communication paths serve to isolate and identify line ground faults.
A bus system with a master station and a plurality of slave stations is described. The slave stations have a connecting switch, with the downstream slave stations having no electric contact with the master station when the connecting switch of a first slave station is opened. In this phase, the first slave station is initialized. Before closing the connecting switch, a test switch is closed, with the current flow being limited by a current limiter. It is thus possible to check on whether the downstream slave station has a short circuit.
A method for identifying the rank of a faulty cell in a chain of cells forming a shift register in a functional element, each cell including a pair of latches acting as master-slave elements having data inputs, clock inputs, and data outputs, each cell being associated with a combinatorial logic block. In one embodiment the location or rank of the faulty cell is determined by placing the faulty functional element in a static mode, applying a square pulse to its data input, observing the output waveform representing variations of input current that occur during propagation of the pulse along the chain, and detecting the absence of these variations, the absence indicating a defective cell just loaded with a data bit. The rank of the faulty cell is determined in one embodiment by comparing the output waveform with that of a known satisfactory functional element, either manually or automatically.
A communication system useful for fire detection which transfers data/commands bidirectionally between a controller and connected transponders on a real time, interactive basis. This system makes possible accurate data recovery, whether a transponder has its output shorted, or although multiple transponders are replying and makes possible the remote determination and constant monitoring of transducer sensitivity, at the controller. The sensitivity can be adjusted remotely at the controller, and different transducers can have different thresholds simultaneously, which can be changed collectively or individually to different settings manually or automatically at the controller. The system transmits reference data for supervision of system accuracy. Compensation for long-term changes is provided for both transponders and reducers in this system.
A method for locating faults or failures in R-F coaxial cable TV transmission facilities is shown and described. A fault locator signal frequency is inserted into a cable system, and low magnitude signals are emitted by means of a band pass filter and radiating element. The radiated R-F is detected to determine coaxial cable system operation. Band pass filters and radiating elements are located at each point to be tested. An apparatus for emitting a controlled narrow band of R-F energy which utilizes a band pass filter and a radiating element is also shown and described. This is the disclosure of intentional, controlled, discriminate R-F radiation used for fault detection and a coupler-band pass filter to accomplish it.
An Ethernet network with redundancy properties and an associated method for detecting and eliminating errors in the network. A redundancy manager (6), which is connected to the line ends of the network (1), checks the status of the network by transmitting and receiving test telegrams. If there is an interruption in the network, the redundancy manager (6) connects the line ends (7, 8) and thereby ensures continued network operation within milliseconds. The network has a loop structure that is less expensive than a dual bus structure even though fast media redundancy is ensured.
