| 摘要 |
PURPOSE:To attain the reliability the same as that of a 2-wire type by connecting lots of receiving/sending stations each provided with a relay part relaying in two-way and branching a relay signal during the relaying by one optical cable line in a chain so as to form the line by one optical cable and to reduce the cost. CONSTITUTION:An optical cable relay section 7 of each slave station 4 turns on any of switch elements 50A, 51A or 50B, 51B depending on the direction of an input optical signal so as to make the output effective, the electric signal of two-way photoelectric converters 49A, 49B is coupled and the converters 49A, 49B are controlled respectively in the optoelectric and electrooptic conversion modes. Thus, the signal is sent to the next slave station 4 between optical cable connection terminals 3A and 3B with no loss. But the signal is branched from the intermediate part of the elements 50A, 50B and 50B, 51B during the relaying and the branch signal is given to a reception terminal RX via an OR gate 52. As a result, when its own station can cope with a call from a master station 2A at any time and in this case, the switch elements 53A, 53B are turned on selectively to attain the transmission to any of terminals 3A, 3B. |
