| 摘要 |
PROBLEM TO BE SOLVED: To make a concentrator able to recognize that GLM is unusable, automatically perform a bypass processing and continue input and output by using a different GLM without manual aid by interrupting power supply to a fault GLM by the changeover of a switch. SOLUTION: On the side of a controller 63, whether or not a fault is generated is detected by a fault detection circuit 632. When the fault is generated, the switch 6411 of this GLM 61 is switched to the side A. By switching it, power to the emission light source 613 of the GLM 61 is interrupted and light emission is stopped. On the side of this concentrator 5, when the power supply to the emission light source 613 is interrupted, it is detected that the light emission from the GLM 61 is interrupted, the GLM 61 is considered as unusable, the bypass processing is performed by switching an optical switch 52 and the input and output by using the other GLM 61 are performed. |
