Abstract: A circuit in which driver units are associated with data networks that are coupled through at least two single transmission channels is provided. The driver units have a logical signal input and a logical signal output on their sides facing away from the data network, with the signal input or signal output of one driver unit being connected with the signal output or signal input of the other driver unit through a signal transmission channel in each case for coupling each of two data networks. A logical coupling control unit is looped into the coupling signal transmission channels. The unit blocks the signal path to the other signal transmission channel when predetermined blocking signal information appears on one signal transmission channel. This ensures that feedback and oscillation effects are suppressed during the transmission of signals over the transmission channels. The circuit can be used for coupling CAN data networks in motor vehicles.

Abstract: In a signal transmission network, such as a data network, having a multiple access bus topology (12) in which many nodes reside and communicate over the same bus, and wherein electrically isolated and/or physically different signal transmission media (17,18,19) are encompassed by the bus (12), and wherein a common protocol is used across the entire network; a multidirectional repeater (10) repeats signals from any one of the signal transmission media to one or more of the other signal transmission media, thereby providing a contiguous logical bus across the different signal transmission media. The multidirectional repeater (10) uses logic transitions, e.g.

Abstract: A data communication system having a plurality of nodes is disclosed. A number of transceivers is provided, each transceiver being coupled to a respective one of the plurality of nodes, for data communication between the transceiver and its associated node. Each transceiver is also provided with a controlled current source. The data communication system is also equipped with a data bus for communication of a transmitted data signal between the transceivers. A current bus which is coupled to each transceiver receives a current signal from the controlled current source when a transceiver is placing the data onto the data bus.

Abstract: A subscriber at a remote location is provided the capability of configuring a multipoint private line network composed of multipoint junction units or hubs that provide alternative functions of permitting exclusive data intercommunication between main lines thereof and selected branch lines thereof when certain selection codes are applied to the main lines without the subscriber having knowledge of the selection codes or the network "mapping". The subscriber at the remote location sends a service request defining the function desired and the ultimate downstream terminal to be interconnected or blocked and a control unit in the network consults a network map to identify the upstream and downstream branch lines to be selected, sending a sequence of selection codes to first select the upstream branch and then select the downstream branch or branches. The control unit also monitors responses of the junction units and reports results to the control location.

Abstract: A multipoint junction unit at a hub office interconnects a main line and a plurality of branch lines, the main line extending to a control station and the branch lines extending to data station line loops, to downstream local offices and to a main line of a multipoint junction unit in a downstream hub office. Normally, the junction unit broadcasts downstream data to all branches and combines upstream data from the branches for propagation up the main line. When a branch line is to be tested, test equipment connected to the upstream main line sends an address sequence to select an upstream branch and, if required, a second sequence to select a downstream branch, whereupon unselected branches are blocked and the selected branches are unblocked to permit passage of upstream and downstream data. The selected branch may thereafter be removed from the network by a "blocking" sequence which blocks the selected branch and restores all unselected branches.

Abstract: A communication system for repeating a data signal received on one input/output line onto one or more other input/output lines while inhibiting the data signal repetition on the input/output line having input data being received thereon. The first bit of the incoming data signal is detected to generate a control signal for a line selector latch. The line selector latch latches in response to the control signal with the appropriate incoming line identification stored therein. This stored line identification is used to control a multiplexer which selects the corresponding one of a plurality of input signal detectors connected to respective input-output lines to supply an input signal to a signal repeater. The stored line identification also generates an inhibit signal to inhibit operation of a line output driver associated with the input/output line on which the incoming data was detected.

Abstract: A multipoint synchronous data network is formed by junction units which provide signal paths that interconnect incoming branch lines to a common outgoing branch. The junction units arranged to combine the branches so that data words on one branch are propagated up the common branch, subject to the condition that only one branch can send to the common branch at a time. Each data word includes a designation whether the word carries message information or control information (such as an idle branch condition). Control words are blocked by the junction unit so that message words from a sending branch are not garbled by control words from idle branches.