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© National Instruments Corporation 5-1 Lab-NB User Manual
Chapter 5
Calibration
This chapter discusses the calibration procedures for the Lab-NB analog input and analog output
circuitry.
The Lab-NB is calibrated at the factory before shipment. To maintain the 12-bit accuracy of the
Lab-NB analog input and analog output circuitry, recalibration at six-month intervals is
recommended. Recalibration is also recommended whenever the input or output configuration is
changed.
Factory calibration is performed with the Lab-NB in its default factory configuration:
• ±5 V analog input range (bipolar)
• ±5 V analog output range (bipolar)
Calibration Equipment Requirements
For best measurement results, the Lab-NB needs to be calibrated so that its measurement
accuracy is within ±0.012% of its input range (±0.5 LSB). According to standard practice, the
equipment used to calibrate the Lab-NB should be 10 times as accurate, that is, have ±0.001%
rated accuracy. Practically speaking, calibration equipment with four times the accuracy of the
item under calibration is generally considered acceptable. Four times the accuracy of the
Lab-NB is 0.003%.
You need the following equipment to calibrate the Lab-NB board:
• For analog input calibration, you need a precision variable DC voltage source (usually a
calibrator) with these features:
- Accuracy ±0.001% standard
±0.003% sufficient
- Range Greater than ±10 V
- Resolution 100 µV in ±10 V range (5
1
/2 digits)
• For analog output calibration, you need a voltmeter with these features:
- Accuracy ±0.001% standard
±0.003% sufficient
- Range Greater than ±10 V
- Resolution 100 µV in ±10 V range (5
1
/2 digits)