| 摘要 |
PURPOSE: To attain inter-slave station communication even when a master station is failed by returning an up optical signal from a slave station to the master station to the down direction to the slave station based upon information from the master station. CONSTITUTION: Optical switches 6-1, 6-2 are connected between the master station 1 and optical star couplers 3-1, 3-2. The switch 6-1 respectively connects its common port Pc, normally-closed port Pb and normally-opened port Pa to the coupler 3-1, the master station 1 and the normally-opened port Pa of the switch 6-2. The switch 6-2 respectively connects its common port Pc, normally-opened port Pa and normally-closed port Pb to the coupler 3-2, the master station 1 and the normally-opened port Pa of the switch 6-1. At the time of receiving a signal S1 informing the generation of a failure from the master station 1 as a switching trigger, the connection modes of the switches 6-1, 6-2 are switched and the common port Pc is connected to the normally- opened port Pa. |
