| 摘要 |
PURPOSE:To prevent down dependent upon a fault by dividing I/O control units and MODEMs into two groups and by confounding them by switching relay contacts and by switching and connecting them to a normal system alternately at a fixed period or by the program control for fault occurrence of one of groups above. CONSTITUTION:For example, when a fault occurs in one of MODEM M00, I/O control unit IOC00, sub-channel unit SCH0, and data channel unit DCH0 of maintenance center MC, central processing unit CC0 or CC1 detects the faulty position to switch the system to the fault redundant constitution system. Switching relay contacts are operated at a fixed period to communicate information with current station LS. Since the data volume transmitted autonomically from current station LS is not large, transfer of charging data, traffic data, and so on is stopped until restoration at a fault time, so that the system can cope with a fixed interrupt time suifficiently if a small-capacity buffer memory is provided in current station LS and center MC. |
