740,876. Automatic exchange systems. TELEFONAKTIEBOLAGET L. M. ERICSSON. Aug. 27, 1953 [Aug. 29, 1952], No. 23746/53. Class 40 (4). In a marker system each subscriber's line, GR49 lights lamp L49 to indicate the marked primary link m1. Relay MR10 connects the marking on the wire c to GR12 which lights lamp L15 to indicate that a register is in the faulty connection, and brings up GR11 to couple the marking wires of the registers to a group of testing relays GR60 ... GR69, whereupon GR69 lights lamp L31 to indicate the register REG1. Relay MR8 couples the first group of secondary links to GR8 which since the marked link m11 is in the first group operates GR7 to switch them through to the testing relays GR50 . . . GR59. Relay GR50 lights lamp L29 which together with the group lamp L13 indicates link m11. If the marked secondary link had been in the second group, relays MR7, GR5 would have lit the group lamp L12. After a time, the timing circuit ZR operates MR5 which releases the marker and so removes the identification marking. However, all the operated testing relays have shunted one of their opposed windings and are held by relays GR14, GR13 until GR13 is released by a key P1. Identification of connection including a particular supervisory circuit. The number of the supervisory circuit say SNR1 preceded by the identification digit is dialled from a subscriber's line, and the identification marking is applied over wire t1 to the wire c connected to the supervisory circuit SNR1. The identifier G operates as described above excepting that since no circuit is completed for GR12, a slowoperating relay GR9 connects up MR9 which releases MR10. Lamp L14 lights to indicate a supervisory circuit and the wires c of the link, connecting circuit and register controller forming a component of a connection can be identified by applying a particular marking to a lead belonging to a known component of the connection and causing an identifier to search for the marking and to indicate the identity of the components of the connection where the marking occurs. The marking is a particular voltage or audio-frequency and is connected automatically or by means of a key or jack associated with the known component. In a cross-bar system each line, link, connecting circuit or register controller is allotted a number and the dialling of this number preceded by an identification digit causes the marker to apply the particular marking to the control wire of the corresponding, component and to cause the identifier to indicate by lamps the components of the marked connection. Subscriber A10 calls subscriber A19. Providing the marker M is free, line relay LR10 operates the group relay MR11 corresponding to the primary switch K11, whereupon a relay MR4 prevents the marker being seized by a register. MR11 connects a first group of selecting relays MR20 ... MR29 to the primary links and MR20, say, pulls up in series with selecting magnet S19 to seize link m1. Relay MR10 connects up a second group of selecting relays MR40 ... MR49 and say MR40 associated with a free register REG1 operates. The operation of a selecting relay from each of the first and second groups completes a circuit for MRS which couples a third group of selecting relays MR30 ... MR39 to half of the secondary links and M39, say, actuates together with selecting magnets S29 and S30 associated with the secondary link m11. If the test is unsuccessful, relay MR7 releases MRS and couples the other half of the secondary links to the selecting relays MR30 ... MR39. Selecting magnet S30 short circuits the high resistance winding of MR40, whereupon in the register REG1 marginal relay E1 pulls up and operates bridge magnet B212 followed by bridge magnets B10, B11 and relay HR11. Selecting magnets S19, S29, S30 fall back, the circuit for MR11 is broken and the marker M is released. In the register REG1, E1 releases slowly and E2, E3 operate to energize a tuning circuit AR and to revert dialling tone from lead Su to the caller. The three digits of the number are registered on switches D1, D2, D3. The first is a code digit indicating a local call and merely causes dialling tone to be disconnected. The second and third result in the closure of contacts d5, d9, respectively. The register REG1 is connected by E5 to the marker M if free and relay MR6 starts a timing circuit ZR. In a circuit over contact d5, TR1 energizes to connect test relay MR2 over contact d9 to the bridge magnet B19 of the called subscriber A19. If the called subscriber A19 is free, MR2 operates MR11 for the first group of selecting relays MR20 ... MR29 to select a primary link and to operate a selecting magnet S10. Relay MR2 also re-operates the selecting magnet S30 associated with the seized secondary link m11. Relay MR9 disconnects MR10, whereupon a supervisory circuit SNR1 say is selected by the operation of one MR49 of the second group of selecting relays MR40 ... MR49. A free secondary link is selected by the third group of selecting relays MR30 ... MR39 and the associated selecting magnets say S39, S20 are actuated; the former shunting the high - resistance winding of MR49 so that R2 connects up the bridge magnet B211 associated with the supervisory circuit SNR1. During the release period of R2 a circuit is completed for MR3 which shunts down MR2 and operates the bridge magnet B19. The bridge magnet of the selector K21 and the relay HR11 corresponding to the primary and secondary links respectively operate and the connection is completed. Relay E4 after some delay operates, releases E5 and so the marker M, and bridge magnet B212 falls back to release the register REG1. The release of R2 completes a circuit over the caller's loop for R3 to ring the called party A19. When A19 answers, R1 releases the caller's line relay LR10 and relay R2. R3 is now connected to the metallic connection between subscribers A10, A19, and initiates release when both subscribers have replaced their receivers. Identification of connection including a particular register. Supposing that because of, e.g. a fault, the line A10 has remained connected to a register REG1 over links m1, m11. The identification is brought about by dialling from a line, say A19, the number allotted to the register REG1 preceded by the appropriate code digit. Thus, in the register seized by the line A19 the identification number is registered by the operation of contacts d1, d4, d9, whereupon relay E6 connects up the marker M, a circuit over d4 is completed to energize TR10 and MR50 follows. Relay MR6 operates. A circuit is made over contact d1 for MR1 which applies a marking over contact d9 and wire t2 to the wire c connected to the register REG1. Relay MR1 energizes MR51 ... MR53 in the marker M and GR13, followed by GR14 in the identifier G. Relays GR15, GR16 operate in turn to bring up TR1 which connects a group of testing relays GR30 . . . GR39 to the wires c of the subscriber's lines A10 ... A19 associated with the primary switch K11. If the marking were not present on any of these lines, the release of GR15 disconnected by GR16 would operate GR18 to cause the next ten lines to be tested by the relays GR30 ... GR39, and the testing would proceed until the marking were found. However, as line A10 is marked, testing relay GR30 and GR17 operate in turn to light lamps L0, L1, respectively, indicating line A10. GR15, GR16 release. Relay TR1 energizes the group relay MR11 which connects the testing relays GR40 . . . GR49 to the links outgoing from the primary switch K11, and supervisory circuits are coupled to the testing relays GR60 ... GR69. Identification of a connection including a particular subscriber is performed by dialling the number of the subscriber preceded by the appropriate code digit, the marking being applied to the wire c of the subscriber's line. Identification of a connection between two subscribers. If both subscribers are in same group of ten and both secondary links are in the same group, the identification is completed as described above. Otherwise only one subscriber and one secondary link is identified at the first attempt. The key P16 ... P20 corresponding to the group of the identified subscriber is thrown, whereupon relays GR15, GR16 ... make a second search by-passing the said group. The key P2 is also actuated to operate MR7, so that the marked link in the second group of secondary links is identified.