| 摘要 |
PURPOSE:To discriminate the deterministic state of an interface signal from an opposite-side device and to secure logical gate control on other similar signals by inputting the control power supply voltage of the opposite-side device from an interface line and comparing the voltage. CONSTITUTION:The output voltage level of the power supply circuit 201 of a controller 2 is sent onto a control voltage monitoring line 5 after the waveform shaping and short-circuit protection of a filter circuit 202. At the side of a peripheral device 1, a filter circuit 102 processes a ripple of the voltage level (s) on the monitoring line 5 and a voltage comparing circuit 103 makes the comparison with a reference voltage (a). When the controller 2 is powered on and the output voltage level (r) rises, it is detected as the comparison level signal (b) of the peripheral device 1 and when it exceeds the reference level (a), a discrimination signal (c) is driven to set a latch circuit 107. The logical control circuit 203 and signal transmitting circuit 204 of the controller 2 are determined and once an interface-enable-instruction signal is supplied to a decoder circuit 105, a set command signal (e) is supplied to a logical gate circuit 106 to set the latch circuit 107. |
