National Instruments NI 6731 Calibration Procedure

Also see for NI 6711: User manual

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National Instruments NI 6731 Calibration Procedure Manual pdf 2 page image

NI 6711/6713/6731/6733 Calibration Procedure 2 ni.comHow Often Should You Calibrate?The measurement requirements of your application determine how oftenthe NI 6711/6713/6731/6733 must be calibrated to maintain accuracy.NI recommends that you perform a complete calibration at least once everyyear. You can shorten this interval to 90 days or six months based on thedemands of your application.Calibration Options: External Versus InternalThe NI 6711/6713/6731/6733 has two calibration options: an internal,or self-calibration, and an external calibration.Internal CalibrationInternal calibration is a much simpler calibration method that does not relyon external standards. In this method, the device calibration constants areadjusted with respect to a high-precision voltage source on theNI 6711/6713/6731/6733. This type of calibration is used after the devicehas been calibrated with respect to an external standard. However, externalvariables such as temperature can still affect measurements. The newcalibration constants are defined with respect to the calibration constantscreated during an external calibration, ensuring that the measurements canbe traced back to the external standards. In essence, internal calibration issimilar to the auto-zero function found on a digital multimeter (DMM).External CalibrationExternal calibration requires using a high-precision DMM. During externalcalibration, the DMM supplies and reads voltages from the device.Adjustments are made to the device calibration constants to ensure that thereported voltages fall within the device specifications. The new calibrationconstants are then stored in the device EEPROM. After the onboardcalibration constants have been adjusted, the high-precision voltage sourceon the device is adjusted. An external calibration provides a set ofcalibration constants that you can use to compensate for the error in themeasurements taken by the NI 6711/6713/6731/6733.