| 摘要 |
PURPOSE:To reduce the increase in the total length of an optical bus with the increase of slave stations and to improve the reliability by monitoring the normal/fault communication state of 1st and 2nd communication loops, selecting the 2nd communication loop when the 1st communication loop is faulty and using both the communication loops against further occurrence of fault to ensure the communication state. CONSTITUTION:A 1st optical communication loop 131 is used for communication in the normal state. When a broken line takes place in the 1st optical communication loop 131, optical switches 1131, 1133 connecting to the 1st optical communication loop 131 are opened and optical switches 1132, 1134 connecting to the 2nd optical communication loop 132 are closed. Furthermore, when both the 1st optical communication loop 131 and the 2nd optical communication loop 132 are faulty, all the optical switches 1131-1134 are closed and optical signals from optical transmitters OS11-OS1N are synthesized by a star coupler 11321 and the resulting signal is distributed to systems. The one is sent to the 1st optical communication loop 131 via the optical switch 1131 and the other is sent to the 2nd optical communication loop 132 via the optical switch 1132. |
