| 摘要 |
PURPOSE:To alter an input process for a signal so that a noise can be excluded and to adapt the device to an increase in the transmission rate of data. CONSTITUTION:The interface device is provided with a buffer 4 and a comparator 6 to which an external input signal is inputted, a selector 5 which selects the output signal of the buffer 4 or the output signal of the comparator 6 and outputs it to an internal circuit, a selecting circuit 7 which outputs a select signal to the selector 5 and outputs a control signal for controlling the level of the reference voltage at the inverted input terminal of the comparator 6 on the basis of a signal outputted owing to communication protocol abnormality due to operation input or program processing of the internal circuit, a circuit which consists of resistances 14, 10, 13, 15, and 16 and generates the reference voltage, and transistors 9 and 12 which bring one end of the resistances 10 and 13 into a continuity condition or a disconnection condition according to the control signal of the select circuit 7. |
