SE306358B - - Google Patents

Abstract

954,044. Automatic exchange systems. SIEMENS & HALSKE A.G. July 22, 1960 [July 23, 1959], No. 25675/60. Heading H4K. In a switching stage in which the possibility of setting up a connection between any free inlet and an outlet of a particular group is independent of whether connections to outlets of other groups exist, and in which such a connection is set up under control of a marker, use is made of testing networks each arranged to cover only the possibilities of connection between the inlets and a single group of outlets, there being as many such networks as there are different types of outlet group, the networks being connected in common to a first group of wires connectable to the inlets to be served, and the outlets of a wanted group being connectable through a second group of wires to that network which is suitable for the outlet group in question. The switches employed are cross-point matrices, the cross-point contacts not being shown. The inlets 1-k are multipled to the column wires, but the outlet (horizontal) multiple is split. The testing networks Sr, Sq consist of two-input AND gates of which the resistors are common to the gates of Sr and Sq, the first input of each gate being connectable via one of the wires PI to an inlet and the second via one of the wires PII to an inlet to which that outlet may have access. The outlet groups have either r or q (q<r) outlets and the corresponding network Sr or Sq is connected up in each case, The out. put conductors of the network gates are connected to the input terminals of a one-at-a-time selector W which chooses one of the inlets which corresponds to a free path through the stage viz., inlet free and outlet free. This determines the inlet and outlet to be connected together, and the marker sets up the required connection. Thus to set up a connection to an outlet of the second row of switch B31 the contacts 311-31k are closed to connect the wires PI to the inlets of B31, contacts 3121-312q to connect PII to the second row outlets, and contacts 123- (k-2)(k-1)k to connect up Sq. Free inlets have negative free potential thereon, and busy outlets positive busy potential. As resistances Z1-Zk have higher values than the forward resistances of G1q-Gkq the busy potential overrides the free potential, so that negative free potential appears only at those inlets of W which correspond to free inlets and free outlets. One such inlet is chosen by the selector W and the connection is set up by the marker (not shown). Specifications 904,463 and 945,357 are referred to.