| 摘要 |
PURPOSE:To eliminate the need for a DC power supply on the side of a coupler which couples a data processor with a data transmission line by supplying specific DC electric power from a DC power supply to the data transmission line and obtaining DC electric power for the coupler from the data transmission line. CONSTITUTION:Capacitors 8 of respective couplers 12-1, 12-2- are so set that DC electric power sent out of the DC power source device 21 to the transmission line is cut off in front of receiver 17 of the respective couplers and data signals sent out of transmitters 16 to the transmission line 10 or data signals inputted from the transmission line 10 to receivers 17 are only passed. Capacitors 27 of both terminal circuits 25-1 and 25-2 are so set that DC electric power sent out of the DC power source device 21 to the transmission line 10 is inhibited from flowing from both terminal parts of the transmission line 10 to the ground and AC data signals sent out to the transmission line 10 are prevented from being reflected at both terminal parts of the transmission line 10. |
