Abstract: A device for connecting a station to a local area network comprising at least one ring includes switching arrangements associated with circuits for regenerating a signal in order to bypass a station when it is out of service and compensate the attenuation and phase jitter caused by the upstream ring segment. This device enables any number of stations to be taken out of service without seriously degrading operation of a ring. The device is usable in local area networks comprising one or more high-speed (125 Mbauds) rings.

Abstract: The interchange system comprises stations connected to a loop link having two rings (A1, A2) making use of a token access method and operating in load sharing mode, with each ring providing all interchanges in the event of the other ring breaking down. Each station has one adapter (1, 2) per ring, a coupler (C), and a terminal (T). Each adapter performs level 1 procedures and lower layer level 2 procedures only. The coupler includes a processor and uses a protocol at the upper layer of level 2 and at level 3 for managing load sharing between the rings, for switching the station onto one ring in the event of the other ring breaking down, and for providing protection against transmisson errors, against messages being duplicated, and against messages being out of sequence, against breakdowns in the adapters and the rings, and against short traffic interruptions due to a station being inserted or withdrawn.

Abstract: A control logic system comprising at least one sub-system including a master processor, two slave processors and an interchange memory which exchanges information between the master processor and the slave processors. The slave processors access a common memory via an interprocessor interface.