| 摘要 |
<p>PURPOSE:To attain the detection of line disconnection by utilizing a current flowing to any direction without fail when no line disconnection exists in a transmission line using a differential type digital transmitter to detect the absence of current. CONSTITUTION:A line disconnection detecting photocoupler 5 is connected in anti-parallel with a data receiving photocoupler 3, and the outputs of both photocouplers are connected to an OR circuit 6. Since the differential digital transmission system flows current to any system at all times, either the photocouplers 3 or 5 goes to logical 1 and the output of the OR circuit 6 goes to logical 1 without fail. When a transmission circuit 2 is disconnected or the power of a transmission circuit 1 is disconnected, the output of the photocouplers 3, 5 goes to ''0'' and the output of the OR circuit goes to ''0''. Thus, the line disconnection is detected.</p> |
