| 摘要 |
PURPOSE:To simplify the wiring at a main loop side by creating a bypass condition when a terminal device is not connected to a branch and connecting a concentrator between a lead-in rope and the branch line when the terminal device is connected. CONSTITUTION:A lead-in rope 2 is inserted into a main loop 1, the main loop 1 is led into the outside, and a concentrator to transmit and receive a data signal between the main loop 1 and a terminal device 6 is connected to the lead-in rope 2. Consequently, the length of a branch line 4 can be shortened. When the terminal device 6 is not connected to the branch line 4, a bypass condition is created, and therefore, without stopping the data transmission at the main loop 1 side, the terminal device 6 is separated from the main loop 1 and repairing and checking can be executed. When the concentrator is provided near the terminal device, the connection of the concentrator and the terminal device 6 can be easily executed. Thus, the wiring constitution of the main loop side can be simplified.
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