| 摘要 |
PURPOSE:To restore a system in trouble to its original state rapidly and accurately by providing a logic circuit and switch with the methods of remembering whether they are in an in-use or stand-by state and then by writing their states in the opposite methods. CONSTITUTION:In the duplex carrier system consisting of in-use system 18 and stand-by system 19, unit 21 that corresponds to the logic circuit controlling switching between in-use and stand-by modes and unit 22 that corresponds to the switch are provided with FF30 and 40 which remember whether thy are in in-yse or stand-by mode. If unit 21 is released due to a fault, etc., FF30 loses its memory contents. However, the memory contents of FF40 stays held normally. As unit 1 recovers from the fault and the electric power source is put to work, timer 51 is driven for period T1 to inhibit new write operation to FF40. In this state, timer 52 is driven for period T2(T2<T1) to open gate 43 or 44 and information on the in-use or stand-by mode of switch driving circuit 41 is supplied to FF30, so that FF30 can be restored to its original state. |
