Patent GB-792231-A (GB)
Title: Automatic circuit selector
IPC: H04L12/54
Filed: 1955-09-12
Abstract: 792,231. Electric selective signalling systems. WESTINGHOUSE AIR BRAKE CO. Sept. 12, 1955 [Sept. 13, 1954], No. 26004/55. Class 40 (1). Relates to a system for automatically selecting a particular pair of a group of electrical circuits in accordance with coded representations of two-digit characters recorded consecutively on a code-bearing medium and is an improvement upon the system described in Specification 789,330. In the Figures, terminals B and N represent opposite terminals of a power supply. Terminals B2 are not energized unless a start relay S and a numberchecking relay NC are energized, and a storage cancellation relay SCR and storage detection relay SDR are not energized. Terminal B3 is only energized when S is energized and no cancellation is being performed by cancel push-button CPB. The selection made is stored in a unit 16 and relay SDR is operated when the store is full to prevent automatic operation of the selector. The system may be manually operated by a selector 19. In operation the push-button SPB is pressed and released to energize relay S which remains energized so long as tape detector contacts 14 are held closed by the presence of the punched tape feeding into the system. Relay NC is picked up and relay M is energized via arm 11 and the "STOP" segment of the distributer to allow the arm. 11 to be. driven by the motor 12 through one complete revolution. The coded marks on the tape, representing the first digit are read by contacts 15 and cause corresponding units digit register relays 1TR ... 5TR to be energized when arm 11 reaches the "OPERATE" segment, the relays being held over their lower winding. Energization of the appropriate units digit register relays cause corresponding tens digit register relays 10TR ... 50TR to be energized in accordance with the first digit and held over their lower windings which in turn causes a tens digit register detector relay 10D to pick up and thus the selected relays 1TR &c. to be released when arm 11 moves off the "OPERATE" segment. Relay 10D conditions the selector so that the next digit will be registered in the units digit register relays. When the arm 11 reaches the "STOP" segment, relay 1D is energized and closes a holding circuit for the energized relays 10TR ... 50TR and opens the circuit of those not energized. The clearing of the units digit register relays causes relay M to be energized to allow the arm 11 to be driven through another revolution and the appropriate relays 1TR &c. to be energized in accordance with the second digit of the code. Relay 10D is released and energy is supplied via contacts of the selected relays 1TR &c. to a line X1 ... X9 corresponding to the second digit, and via contacts of the selected relays 10TR &c. to a line X10 ... X90 corresponding to the first digit of the code. The lines X1 ... X9 and X10 ... X90 are connected to corresponding terminals of the storage device 16. When the arm 11 returns to the " STOP" position it is locked and the system returns to normal. If an error is made in the preparation of the tape characters "x, x," represented by energization of relays 10TR, 40TR, 50TR, and 1TR, 4TR, 5TR are marked on the tape immediately after the error. A storage cancellation relay SCR operates with this combination and removes energy from B2 to restore all relays to normal after which the correct information is entered into the system. Contact b of relay SCR may be used in a manner not described to cancel information previously entered into the storage unit. If an error occurs in the tape and the second digit is omitted a space mark is punched which causes relay 3TR to be energized. Relays 10D, 1D and NC will be energized from the previous digit registration. Energization of 3TR causes a relay FS to pick up and open the circuit of relay NC to cancel the registration in the digit registering relays including 3TR. The system then reverts to normal. If a figure shift symbol is coded on to the tape instead of a digit, relays ITR, 2TR, 4TR, 5TR are energized and this also causes relay FS to operate and the registrations to be cancelled.