| 摘要 |
PURPOSE:To minimize a transmission disable range at the generation of a fault by judging as lines are short-circuited when a voltage between signal lines is at a low level for a setting time or over, and disconnecting a signal line connected to the short-circuited side. CONSTITUTION:Each terminal device 1 consists of a pull-up resistor 3 applying a DC voltage VCC between a couple of signal lines 2, a transmission means 4 comprising a transistor (TR) Q0 freely short-circuited based on the data to be transmitted, a reception means 5 and a logic circuit 6 processing data. Further, the terminal device 1 is provided with a short-circuit detection circuit (not shown) detecting that a voltage between the signal lines 2 is at a low level for a prescribed time or over, and in case of the detection of short-circuit, A TRQ1 or Q2 is turned on so as to activate a relay R1 or R2. Then the short-side of the signal line 2 is disconnected. Thus, the transmission disable range due to a short-circuit fault is minimized. |
