| 摘要 |
PURPOSE:To speed up measuring operation by removing an error in measured voltage due to equivalent stray capacity which is present on the side of the input bus of an A/D converter by a discharging circuit. CONSTITUTION:The discharging circuit 7 is constituted by interposing the series circuit of a resistance R and a relay contact point rs between the ground and a bus 10 connected from a multiplexer MPX to a DC measuring instrument DCM closely to the input terminal 9 of the A/D converter of the bus 10. Then a driving pulse Ps with a period T is applied to the contact point rs at the time of voltage measurement, and consequently the contact point rs is turned on to set the voltage at the terminal 9 to a zero state temporarily. Then the voltage V1 of a measurement object point 11 is inputted to the A/D converter. Even when a voltage V2 at a next measurement object point 12 is inputted to the A/D converter, the contact point rs is turned on with the pulse Ps before the voltage V2 is measured to clear the remaining voltage at the time of the voltage V1 to a zero state temporarily, and a DC voltage is inputted to the measuring instrument DCM. Namely, the contact point rs is operated associatively with the switching of switches RS1-RSN of the multiplexer MPX to clear remaining charges due to the stray capacity of the bus 10.
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