| 摘要 |
PURPOSE:To prevent the effects of a fault of a slave station on the entire system by always branching signals given from the preceding stations through each slave station by means of an optical means. CONSTITUTION:In a normal mode, signals sent from an input terminal 201 are processed by a controller at a slave station and then delivered through an output terminal 203. In case the preceding station stops the signal transmission or transmits random signals, a fault is detected and no synchronizing pulse 302 is delivered. Furthermore, the output of a timer 303 is set at a low level. Then the signal of a gate 210, i.e., the signal given from an input terminal 202 is turned into a reception signal 5 within a switching circuit 205. The signal 5 is branched optically to a by-pass 211 by an optical branching device 206. Thus the signal of the preceding station flows to the bypass 211 to avoid the break of a loop despite the service interruption of an O/E 207 or an E/O 208. |
