| 摘要 |
PURPOSE:To form the analog input device and its output device in one body and operate it efficiently, by executing A/D conversion of an input analog signal and outputting it as a digital signal, and also executing D/A conversion of an input digital signal and taking it out as an analog signal. CONSTITUTION:An output of the resistance 13 is compared with an output of the relative resistance 14 one after another in the A/D conversion check mode, and if the relative value coincides, it can be known that the function of the A/D converter is normal. Subsequently, the control circuit 22 which has received and A/D conversion mode signal samples an input analog signal Ai, converts it to a digital signal by the A/D converter, and outputs it successively as a digital signal from the relative resistance 14. On the other hand, after it has been confirmed that the function of the D/A converter is normal, the digital signal is input to the resistance 13 in the D/A conversion mode, and a D/A converted signal is output through the voltage holding device 19. In this way, it is possible to form the analog input unit an its output device in one body and operate it efficiently. |
