A sample of a normal data communications stream producing an error is thereafter employed via a loop back arrangement as a test sample data stream for error detection.

This invention relates to a coupler which allows a host processor such as, for example, a personal computer or point of sale device or the like to communicate with and control a portable data carrier. A portable data carrier is a portable device which contains integrated circuit(s). Examples of portable data carriers are Integrated Circuit Cards, data keys, super smart cards, and smart coins. The coupler is adapted to receive the card in a standard card receptacle or card reader to establish connection between the card and a connector in the coupler to which the necessary control signals are applied. The presence of an integrated circuit card is detected in the coupler's card connector terminal which provides a card present signal to the host processor. The host, in turn, provides Clear-To-Send (CTS), Request-To-Send (RTS), Data-Set-Ready (DSR) and Data-Terminal-Ready (DTR) signals. The input/output data from the input/output line channel of the IC card is connected to the Transmit-Data (TX) and Receive-Data (RX) lines of the host processor without the necessity of retransmitting characters communicated between the portable IC and on data carrier and the host processor.

In a multiplex communication method for implementing multiplex communication between a plurality of circuit units, a format of a transmitted data signal not only is formed of serial data consisting of first data, second data that has the same content as the first data, and a parity that indicates the number of logical 1s or logical 0s forming the first data and the second data is even or odd, but also selects as regular data in such a manner that when the transmitted data signal is received, if the first data and the second data are compared with each other and judged to be coincident with each other from the comparison, then the coincident data is selected as the regular data and that if the first data and the second data are judged to be different from each other from the comparison, then a logic of the parity is checked and either the first data or the second data corresponding to the logic of the parity is selected as the regular data.

A data transmission system for an automotive vehicle includes a plurality of control units installed on the vehicle, and a transmission line connecting the plurality of control units with each other. The transmission line comprises a pair of signal lines to which digital data signals having opposite polarities are delivered for transmission of data. Each of the plurality of control units comprises a first receiver for receiving both of the digital data signals having oppositive polarities and outputting a first difference signal indicative of a difference between the digital data signals, a second receiver for receiving one of the digital data signals and outputting a second difference signal indicative of a difference between the one of the digital data signals and a predetermined reference level set thereto, and a third receiver for receiving the other of the digital data signals and outputting a third difference signal indicative of a difference between the other of the digital data signals and a predetermined reference level set thereto. Detecting of which of the pair of signal lines is faulty, is carried out based on the first difference signal output from the first receiver, the second difference signal output from the second receiver, and the third difference signal output from the third receiver.

A power network control system has a plurality of digital modules interconnected. A master logic unit in the network communicates with a specialized protocol to slave logic units in each module to provide a reliable power control system for selectively (or generally) instructing modules to turn on or to turn off the local power source.