| 摘要 |
PURPOSE:To cancel an error caused by a disconnection detecting power source, by connecting a DC power source through a resistor between a coupling resistor connected in series to an analog signal line for receiving an input of a sensor, and an input device. CONSTITUTION:A thermocouple 1 is connected to a cold junction part 3 through a thermocouple compensating conductor 2, and a voltage corresponding to a temperature difference of the thermocouple 1 and the cold junction part 3 is inputted to an analog input device 4 through an analog signal line to which resistors RP, RN are connected in series. A disconnection detecting part 5 consisting of a DC power source ES and resistors R1, R2 is connected to the cold junction part 3 side, and at the time of disconnection, an input voltage of the input device 4 is scaled out. Also, to the input device side of the line, an error canceling part 6 consisting of resistors R3, R4 and a variable DC power source EC is connected, and an error influenced over a measuring voltage by the DC power source ES at the time of non-disconnection is canceled by adjusting the DC power source EC.
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