METHOD OF MAINTAINING THE FUNCTIONING APTITUDE OF A DIGITAL INFORMATION TRANSMISSION ARRANGEMENT, AND ITS APPLICATION

摘要

A data transmission system comprising a plurality of terminal units each having at least one input and at least one output connected such that each connected input of a terminal unit is connected to a connected output of another terminal unit. Each terminal unit with at least two input connections comprises a changeover switch to provide for incoming signal induced connecting of one of the inputs to a receiver circuit for recognizing and receiving certain signals. A test circuit is connected to the receiver circuit for determining if the test signals received are free from errors. An error sum counter is connected to the test circuit and to the changeover switch. At least one of the terminal units comprises an emitting provision for test signals, which is connected to the outputs of the terminal unit to provide for checking of the functioning of the transmission system. For each missing or defective test signal train received an error message is fed to the error sum counter for increasing the count value. Simultaneously an error signal generator provides an output error signal.