| 摘要 |
PURPOSE:To reduce the power consumption and heat generation of an input side by allowing an input data fetching circuit to operate plural times in one cycle of serial data transmission to fetch input data plural times and to perform logical operation by majority decision, and using the result as normal input data. CONSTITUTION:The input interface 13 of an input unit fetches input signals from input signal lines SW1...SW8 connected to input terminals IN1...IN8 and stores them in a latch circuit 31 temporary. This circuit 31 receives a timing signal T from a transmitting circuit 12 through an inverter 35 to latch the input data synchronously with the signal T. When the photocoupler 32 of the circuit 31 is off and the switch SW1 is on, an LED1 and a high resistance R1 are connected to an AC power source 34 through a common terminal COM and almost no current flows through this circuit. On the other hand, when the coupler 32 is on, this circuit is connected to the power source 34 through the LED1, a low resistance R2, the coupler 32, and the terminal COM and a feed current flows. |
