| 摘要 |
1500860 Data communication system YOKOGAWA ELECTRIC WORKS Ltd 4 June 1976 [13 June 1975] 23144/76 Heading G4H A data communication system comprises a pair of transmission lines 1, 1<SP>1</SP> connecting a master station with a series of subsidiary stations 31 &c. each arranged to receive signals from the master station by way of a first photocoupler 311 &c. and to transmit signals to the master station by way of a second photocoupler 313, 323,... Each photocoupler comprises a light emitting diode and a phototransistor arranged as shown. The master station contains two current sources 21, 21<SP>1</SP> operated by switches 22, 22<SP>1</SP> for transmission and reception. A diode D<SP>1</SP> isolates photocouplers 313 &c. during transmission to the subsidiary stations, and a diode 312 &c. by-passes photocoupler 311 &c. during transmission from the stations to a receiving circuit 23. |
