| 摘要 |
<p>PURPOSE:To detect a fault quickly and to attain proper countermeasure by supplying a same current to two transmission lines so as to be finally supplied to a secondary winding of each pulse transformer of each node and discriminating it in the event of disabled communication that either of the two transmission lines is broken. CONSTITUTION:A control circuit 33 of a fault diagnostic device 9 outputs a signal at the detection of a broken line to close switching circuits 30-32 to connect transmission lines 2, 3 to a power supply +Vcc and to connect a transmission line 4 to ground GND. Suppose that the transmission line 3 is broken at a point P, then a current 1 flows from the power supply +Vcc to the transmission line 2 but does not flow to the transmission line 3. Thus, the current I flows from one direction of terminal 12a to 12c to a secondary winding 12 of a pulse transformer 10 connecting to the transmission lines 2, 4 of a node 5 to unbalance the current in the secondary winding 12, resulting that the core of the pulse transformer 10 is saturated. As a result, no communication is enabled for the node 5.</p> |
