259,642. Standard Telephones & Cables, Ltd., (formerly Western Electric Co., Ltd.), (Polinkowsky, L.). June 15,1925. Automatic exchange systems. - A registercontroller of the code-translating type is arranged to give correct translation for office codes having different numbers of digits. For example, offices in busy parts of a network may have 2-digit codes whilst suburban offices have 3-digit codes. The invention is described with reference to a register-controller, working on the reverting- impulse principle, in which the translation is determined by a rotary switch a - - h, Figs. 1 and 2, which hunts for terminals marked by the code-digit registers. This switch is started up as soon as the minimum possible number of code digits has been received, in this case two, and if necessary the switch makes a further movement after the receipt of a. third code digit. Discrimination between 2- and 3-digit codes is effected by a relay Tdr which energizes in the case of all 2-digit codes to ensure that all succeeding digits shall be treated as numerical digits. The registercontroller shown is designed for use at first with only 2-digit codes, but, by certain changes of wiring, it is readily modified for us.e with both 2- and 3-digit codes. If the number of exchanges in the network exceeds the capacity of the translating switch, two or more such switches which hunt simultaneously may be provided. Register-controller designed for 2-digit codes only. In this case only the full-line connections shown in the drawing are employed. When the register-controller is taken into use, relay Lbr completes a circuit for relays Lmr, Csr and the instepping sequence switch R4 moves to its 2nd position. Relay Isv then energizes over the calling loop, locks up relay Lbr and releases relay Lmr which causes switch R4 to move to its 3rd position, in which it stops owing to the operation of relay Ocr over cam B. The impulses of the first digit are repeated by relay Isr to relays Lmr, Csr, the latter further repeating them over cam N to the first register A. At each impulse relay Csr closes a locking circuit for itself and relay Lmr over cam S and contacts of the stepping magnet. Relay Lmr which remains operated during the digit unlocks relay Ocr, and at the end of the digit the relapse of relay Lmr completes a circuit for switch R4 which moves to its 4th position. The second code digit passes in a similar manner to register B and the four numerical digits are recorded on registers C, D, A, B, respectively. Relay Ocr is not operated when the sequence switch passes between positions 6 and 7 so that the switch passes the 7th position and after all the digits have been received stops in position 10. When the switch R4 moves to its 5th position after the receipt of the two code digits, the power magnet PT of the translating switch is energized and the switch hunts until a circuit is completed for the test relay Ttr over cam E, wiper a of the translating switch, wipers b of the A and B registers and wiper b of the translating switch. The test relay stops the switch and completes circuits for relays Far, Sar, the former of which causes the outstepping sequence switch R5 to move out of its normal position whilst the latter completes restoring circuits for the A and B registers so that these may be used again for numerical digits. The transmission of the routing digits proceeds in known manner under the control of wipers d - - g of the translating switch, whilst wiper h in conjunction with cams F, G of switch R5 serves to suppress one or more of these digits if desired. Special-service call. For such a call, in which two code digits only are dialled, the appropriate contact in the bank of wiper h of the translating switch is wired to the upper left contact of cam G of switch R5 so that a relay Spr is energized which completes a circuit for driving switch R4 to position 10 and a further circuit for moving switch R5 beyond position 10. Dialling an unused code. If the translating switch fails to find marked terminals within a predetermined time a thermal relay Hwr operates and causes the switch to stop on spare terminals from which the call is routed to an operator. Register-controller designed for both 2- and 3- digit codes; 2-digit code dialled. When the register-controller is extended to include 3-digit codes, the full line connections marked with a cross are removed and the dotted-line connections are added, these including an additional register E. When a two-digit code is dialled, the translating switch is started as before but the circuit for the test relay in the 6th position of switch R4 is extended over wiper c to relay Tdr which effects circuit changes to prevent the switch R4 from stopping in position 7 and to remove the switch E from the circuit. The six digits are therefore recorded on the registers A, B, C, D, A, B, respectively, as before. 3-digit code dialled. In this case, the translating switch is started in position 5 of switch R4 as before but when the switch moves to position 6, the circuit of the test relay is opened at cam H so that the switch hunts further, if necessary, until a new circuit is completed for the test relay over wiper c of the translating switch and wiper b of the C register. Since relay Tdr is not energized, relay Ocr is energized when the switch R4 moves from position 6 to 7 so that the switch will stop in position 7 in which the second numerical digit is recorded on register E, the last two numerical digits passing to registers A, B as before. Specifications 206,578, 208,501, 256,544 and 257,307 are referred to.