Connection unit for time division switching system

Connection unit for linking subscribers to an exchange in a time switching system comprising a plurality of subscriber circuits, a plurality of subscriber junction supervisory circuits connected to said subscriber circuits, a plurality of time multiplex digital terminal sets, at least one space-time concentrator connected to said subscriber circuits and a logic control unit operating on a time-sharing basis with said concentrator, said concentrator comprising a concentration network having at least an input stage and an output stage, the input stage consisting of a plurality of groups of switches in variable numbers connected in parallel to said subscriber circuits to adapt the number of inputs of a group to the traffic of the subscriber to be serviced, a junctor set connecting the output stage of said concentrator to said digital terminal sets, and memory means including line and line state memories connected to said junctor set for storing the state of the connections and the orders received from the logic control unit.