NI 9235/9236 Calibration Procedure

Calibration Executive 6.0 Help

Edition Date: July 2020

Part Number: 374564Y-01

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This topic contains information for calibrating the NI 9235 and NI 9236 using Calibration Executive.

Calibration Executive Procedure Features:

Adjustment

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Manual Mode

Supported
Selectable Test Points

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Approximate Test Time: 40 minutes

Test Equipment|Test Conditions|Device Setup|Test Limit Equations

Test Equipment

The following table lists the test equipment required for calibrating NI 9235/9236 modules.

InstrumentRecommended
Model
Requirements
CalibratorFluke 5500AIf this instrument is unavailable, use a calibrator with generation of resistances in the ranges of 108 Ω to 132 Ω and 315 Ω to 385 Ω with 0.01 Ω resolution, an accuracy of at least 90 ppm, and automatic lead wire compensation.
Note Note  The Fluke 5700A and Fluke 5720A calibrator models cannot generate the resistances required to calibrate the NI 9235/9326.
DMMNI 4070If this instrument is unavailable, use a multi-ranging 6 1/2-digit DMM with an accuracy of at least 40 ppm.
ChassiscDAQ-9178
Connecting WiresConnections between the module and the calibrator are insensitive to connection resistance except between the calibrator LO terminal and the module RC terminal. The resistance of this connection must be less than 200 mΩ to limit bridge linearity errors. The measurement accuracy verification TestLimits assume this requirement is met.

Test Conditions

The following setup and environmental conditions are required to ensure the NI 9235/9236 meets published specifications.

  • Keep connections to the device as short as possible. Long cables and wires act as antennas, picking up extra noise that can affect measurements.
  • Use shielded copper wire for all cable connections to the device. Use twisted-pair wire to eliminate noise and thermal offsets.
  • Maintain an ambient temperature of 23 °C ±5 °C. The device temperature will be greater than the ambient temperature.
  • Keep relative humidity below 80%.
  • Allow a warm-up time of at least 10 minutes to ensure that the NI 9235/9236 measurement circuitry is at a stable operating temperature.

Device Setup

  1. Install the NI 9235/9236 in slot 8 of the cDAQ-9178 chassis. Leave slots 1 through 7 on the cDAQ-9178 chassis empty.
  2. Configure the hardware using Measurement & Automation Explorer (MAX).
  3. Launch the Calibration Executive procedure and complete the setup wizard. Refer to NI 9235/9236 Calibration Setup for detailed connection instructions.
Note Note  If the NI 9235/9236 module fails after calibration, return it to NI for repair or replacement.

Test Limit Equations

The following test limits are derived from the published specifications found in the NI 9235/9236 Calibration Procedure.

Accuracy

TestLimits = NominalValue ± AbsoluteAccuracy

AbsoluteAccuracy = NominalValue * GainError + Range * OffsetError

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