| 摘要 |
PURPOSE:To increase the number of parallel connection of slave stations, by increasing an input impedance of the slave station, through the provision of a power supply exclusively for use by a reception circuit at the slave stations. CONSTITUTION:A slave station B is provided with a power supply 16 exclusive for reception circuit. A master station A switches power supplies 1, 2 with a contact 6 of a relay 7 to transmit a transmission signal shown in Figure. A reception circuit B1 of a slave station B detects a transmitted signal (reception signal at slave station in Figure) at the base of a transistor 11 via a high input resistor 10 for amplification (current conversion). A light emitting element 13 of a photocoupler is driven with this detected signal for the detection at a reception signal circuit 15 via a photodetector 14. A return signal from a slave station turns on or off a light emitting element 18 with an oscillation circuit 20 of a return signal circuit B2, to turn on or off a photodetector 17. Thus, a return signal current as shown in figure can be flowed to a transmission line 9 with the power supply 2 of the master station. |
