| 摘要 |
PROBLEM TO BE SOLVED: To provide a control system of T-S-T three-stage structure for an electronic exchange to improve its reliability by avoiding such a case where an entire system is set in a switching disabled state owing to the fault of an S-stage switch module and then assuring the connection for every T-stage module. SOLUTION: In a normal T-S-T three-stage structure, the inputs of tertiary switches 120 to 12n select the inputs sent from secondary switches via selection circuits 500 to 50n. If a fault occurs in S-stage switch modules 210 to 21n, processors 130 to 13n of T-stage switch modules 100 to 10n control the circuits 500 to 50n to select the inputs of its own modules 100 to 10n. In other words, each of scattered T stages functions as an exchange by itself even if the abnormality occurs at an S stage in a system of the T-S-T three-stage structure. Therefore, the subscriber device stored in each T stage and a network can be switched to improve the reliability of an electronic exchange. |
