| 摘要 |
<p>PURPOSE:To judge whether an abnormality is generated from the connection line or the slave device of a master/slave devices. CONSTITUTION:A control signal and a voice signal are respectively transmitted from a master device 40 through a line 52 and a line 54 to a slave device 42. A protect circuit 64 is operated according to a transmission request signal superimpose-transmitted through the line 52, and when the abnormality is generated at the slave device 42, an abnormality detection signal is prepared. A protect release circuit 66 generates a control signal detection signal while receiving the control signal. A protect switch 62 generates an H level signal when an operation request signal is not supplied, generates an L level signal when the transmission request signal is supplied, and when the abnormality detection signal is not generated, and generates the H level signal when the transmission request signal is supplied, and when the abnormality detection signal is generated. When the control signal detection signal is generated in that state, the signal is changed from the H level to the L level. The output signal is superimposed on the line 54, and transmitted to the master device 40. When the output signal of the switch 62 is the L level, a transmitter 46 is operated.</p> |
