| 摘要 |
<p>PURPOSE:To detect abnormality with simple circuit composition by providing to the transmission line input part of a receiving part a detector abnormality detecting circuit using a photocoupler in which photodiodes are connected in inverse-parallel. CONSTITUTION:When two wires of a transmission line 3 are disconnected, since both of photodiodes 51 and 52 stop light emission, the logical level of an abnormality detecting signal AL becomes a HIGH level, and the signal AL can detect the abnormality. Further, when one wire of the transmission line 3 is disconnected, since both the above-mentioned photodiodes stop light emission in the same manner as that in the case when the two wires are disconnected, the logical level of the abnormality detecting signal AL becomes the HIGH level, and the signal AL can detect the abnormality. Moreover, when the electronic circuit of an output circuit 2 becomes abnormal and outputs an output signal having the same level, the abnormality can be detected in the same manner as that in the case of the occurrence of the abnormality in the transmission line. Thus, the abnormality can be displayed on the console panel of the title electronic device using the abnormality detecting signal AL, and further, an alarm can be also generated.</p> |
