Scanning circuits

Claim 1

A time division multiplex data switching system controlled by a central data processing machine, the said switching system comprising a switching network, a plurality of inlets connected to a first plurality of junctors for coupling a group of trunks to the switching network, said first plurality of junctors including means for making a series-parallel conversion of signals received over a first plurality of the inlets, means coupled to make a parallel-series conversion of signals from the switching network to a second plurality of inlets, said junctors including circuits for detection and interpretation of the signals received over said first plurality of inlets, said junctors each including a signalling memory circuit in which are stored for each channel of a group of signals the expected signalling state and the indication of change or of the lack of change of state of signalling with respect to the expected state, a second plurality of junctors connected to outlets of the switching network, each of said second plurality of junctors including four memories including a data memory, a time path memory and two space path memories intended for establishing a connection between two channels, means coupling said memories to be updated by the data processing machine in relation to the communications in course, a clock circuit for supplying cyclic signals, circuits associated with said signalling memories to enable detection each time the channels processed receive a call or change their states, a sequential circuit enabling the determination of the time and space coordinates of a calling channel or of a channel changing its state, said sequential circuit including means for scanning for new calls and other changes of state and means for first determining the coordinates of the calling channels and in storing them in a first memory, means for determining thereafter the coordinates of the channels changing their states and in storing them in a second memory, means for scanning once again the new calls and means for writing their coordinates in a third memory, means for scanning once more the other changes of state and means for writing their coordinates in a fourth memory, and means for starting again the operations described hereabove in the same order.