Example Code

Calibrating the PXI-6683(H) using the NI-Sync Calibration API

Code and Documents

Attachment

Overview

The attached LabVIEW code demonstrates how to use the NI-Sync calibration API in order to calibrate the NI PXI-6683(H) module.

Capture.PNG

Steps to Implement or Execute Code

To perform a calibration adjustment:

  1. Ensure you have completed all steps in the Hardware Setup section below.
  2. Run the top-level PXI-6683 Calibration VI.
  3. Enter the device name of the NI PXI-6683 Series board to be calibrated in the NI PXI-6683(H) Unit control.
  4. Click the Calibration Adjustment button.
  5. Enter the external calibration password and click OK.
    • Note: The default calibration password is ni.
  6. The utility will search for the best voltage setting for the TCXO until the TCXO frequency is within 0.1 ppm of the 10MHz reference clock on PXI_CLK10. The measurement for each voltage setting will last about 20 seconds. When the voltage setting is found, the calibration EEPROM will be updated and read-back for verification. If a voltage setting within 0.1 ppm of the 10MHz reference clock cannot be found after 16 attempts, the calibration adjustment is considered failed, and the EEPROM is not updated.

To verify calibration:

  1. Ensure you have completed all steps in the Hardware Setup section below.
  2. Run the top-level PXI-6683 Calibration VI.
  3. Enter the device name of the NI PXI-6683 Series board to be calibrated in the NI PXI-6683(H) Unit control.
  4. Click the Verify Calibration button.
  5. Enter the external calibration password and click OK.
    • Note: The default calibration password is ni.
  6. The verification process lasts about 10 seconds, after which, calibration information stored in the calibration EEPROM and the measurement just taken is displayed. Verify the frequency of the TCXO is within the limits required by your application.


Requirements

Software

  • NI-Sync 3.4 or later
  • DAQmx 9.5.5 or later
  • LabVIEW 2012 or later

Hardware Setup

  1. Install the NI PXI-6683 Series board(s) to be calibrated in the PXI chassis.
  2. An external 10MHz reference clock must be present as PXI_CLK10 in the PXI chassis in order to calibrate the PXI-6683(H). This can be achieved by one of these two options:
    • Connect your external 10MHz reference clock to the 10MHz REF IN BNC connector at the back of most National Instruments chassis.

    • Use a Timing and Synchronization board in the Timing Slot of the chassis to replace PXI_CLK10 with your 10MHz reference clock.

      • If you are using the Timing and Synchronization board’s OCXO as reference, it must be configured to route its on-board oscillator to PXI_CLK10_IN.

      • If you are using an external 10MHz reference clock, connect your reference to the Timing and Synchronization board’s CLKIN input and configure the board to route CLKIN to PXI_CLK10_IN.

    3. Wait the required warm-up time for the reference to achieve the desired accuracy. Refer to the user manual for the device providing the 10MHz reference clock to determine          the warm-up time necessary to achieve required accuracy.

Required Test Conditions

The following setup and environmental conditions are required to ensure the NI PXI-6683 Series

board meets published specifications following calibration.

  • The 10MHz reference clock for calibration must be present at PXI_CLK10 in the chassis

being used.

  • PFI0 of the NI PXI-6683 Series board being calibrated must not be connected to anything.
  • Keep cabling as short as possible. Long cables and wires act as antennae, picking up extra

noise that can affect measurements.

  • Verify that all connections, including front panel connections and screws, are secure.
  • Maintain ambient temperature of 24 °C ± 3 °C.
  • Keep relative humidity between 10% and 90%, noncondensing.
  • Allow at least 15 minutes of warm-up time for the NI PXI-6683 Series module being

calibrated.

Example code from the Example Code Exchange in the NI Community is licensed with the MIT license.

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