Abstract: In a multi-data transmission system utilizing two or more parallel data-transmission lines in LAN, erroneous data distribution occurring in the data-transmission lines is detectable. A data transmission apparatus includes: a plurality of data-transmission lines arranged in parallel with each other, and a plurality of transmission stations coupled via the plurality of data-transmission lines to each other. Each of the transmission stations includes adders for adding to send data, transmission-line information representative of a specific data-transmission line so as to obtain send data with the specific line information; and, receiver/detector for receiving the send data with the specific line information which has been transmitted from one transmission station, in order to judge whether or not the received send data contains the correct specific line information. Accordingly, erroneous data distribution occurring in the data-transmission lines can be detected.

Abstract: A bus-redundancy type apparatus for a transmission line is disclosed, which comprises first and second transmission lines respectively provided as a normally operating transmission line and a stand-by transmission line for data transmission in a transmitting system, in which bus-access control is performed, first and second carrier detectors for receiving transmission data from said respective first and second transmission lines and for detecting carrier components in the transmission data, a carrier-disappearance detector for receiving the results of detection by the first and second carrier detectors and for providing a carrier-disappearance signal when it is detected that neither of the first and second carrier detectors detects any carrier component, a transmission line-switching command generator for providing a transmission line-switching command, to select either one of the first and second transmission lines, a switching unit for selecting transmission data from the first and second transmission lines

Abstract: A repeater for a transmission system which can pass signals in either of two directions. Each direction has a signal detection circuit associated with it. Upon detection of the beginning of a signal, the signal detection circuit enables an associated driver to pass the signal in the appropriate direction and at the same time disables the other signal detection circuit so that a signal will pass in only one direction at a time. An end flag detecting circuit monitors for certain characteristics associated with the end of the signal, and upon detection causes both drivers to be disabled and both signal detection circuits to be reset so that they can again detect a signal passing in either direction.

Abstract: A data transmission system having a common request line and a special request line in addition to a transmission line. The special request line has priority over the common request line. A plurality of node stations are multi-drop connected to the transmission line. Among the node stations, a supervising station is connected to the special request line and takes precedence over other slave stations to become a master station. The master station collects data from the slave stations. The station connected to the common request line can assign a master control function to any station requesting to be assigned the master control function within a short period of time. Each station has an auto response control circuit. The master station automatically collects data by the auto response controlling circuit independently of the microprocessors of the slave stations.