| 摘要 |
PURPOSE:To increase the flexibility of transmission signal circuit by a party line system and to improve noise resistance by adopting wired OR coupling for a transmitting photocoupler so that the output of said photocoupler is driven by current and a receiving photocoupler is driven by constant voltage. CONSTITUTION:The output of a repeater A2 and the outputs of transmitters T5, T6 are wired-OR-coupled by respective photocouplers PC1-PC3 at a point S1. When one of the photocouplers PC1-PC3 is connected, the point S1 is earthed. Consequently current is made flow from a terminal V2(+) to a point S2. Receivers R6, R5 receive signals by current flowing into a photocouplers PC5, PC4 and a Zener diode DZ1 and a repeater A4 is driven by current flowing into a constant current source E. |
