| 摘要 |
PURPOSE:To minimize the influence of abnormality by double connecting a primary station for optical communication transmission and plural secondary stations into a loop clockwise and counterclockwise and judging a trouble to switch the used communication destination if a reception response is not returned. CONSTITUTION:A primary station 20 and plural secondary stations A-I are double connected into a loop by a clock wise line 18 and a counterclockwise line 19 of optical fibers. If the line 18 between secondary stations C and D is disconnected, the secondary station D judges the trouble because of no reception response and switches the secondary station of the transmission destination from the station C to the station E. The signal from the station D is broken in the station C, and the station C switches the station of the transmission destination from the station D to the station B. If the station D is faulty, stations C and E detect the break of the signal from the station D and switch stations of transmission destinations from the station D to stations B and F respectively. Thus, the influence of abnormality of the system is minimized with simple equipments. |
