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CALIBRATION PROCEDURE
NI PXI-5422
This document contains step-by-step instructions for writing a calibration
procedure for the NI PXI-5422 arbitrary waveform generator.
Contents
Conventions ............................................................................................ 1
Introduction............................................................................................. 2
What Is Calibration? ........................................................................ 2
Self-Calib
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Adjusting the Analog Output ....................................................35 Adjusting the Oscillator Frequency...........................................52 Adjusting the Calibration ADC.................................................55 Closing the External Adjustment Session .................................60 Calibration Utilities .................................................................................61 MAX.......................................................................
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What Is Calibration? Calibration consists of verifying the output accuracy of a device and correcting for any output error. Verification is measuring the performance of a device and comparing the results to the specifications of the device. NI calibrates every NI PXI-5422 at the factory. During the factory calibration process, the calibration constants are stored in an onboard EEPROM. These values are loaded from this EEPROM and used as needed by the NI PXI-5422. The NI PXI-5422 supports
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The output accuracy requirements of your application determine how often you should externally calibrate the NI PXI-5422. NI recommends that you perform a complete external calibration at least once every two years. You can shorten this interval based on the accuracy demands of your application. Refer to the External Calibration Options section for more information. Software and Documentation Requirements This section describes the software and documentation required for both self-calibra
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calling a 32-bit DLL. Many of the functions use constants defined in the niFgen.h file. To use these constants in C, you must include niFgen.h in your code when you write the calibration procedure. Refer to Table 1 for file locations. Table 1. Calibration File Locations File Name and Location Description IVI\Bin\niFgen_32.dll The NI-FGEN library, which provides the functionality for calibrating the NI PXI-5422. IVI\Lib\msc\niFgen.lib Allows you to create applications that call function
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Documentation For information about NI-FGEN and the NI PXI-5422, you may find the following documents helpful: NI Signal Generators Getting Started Guide NI Signal Generators Help NI PXI-5422 Specifications NI-FGEN Instrument Driver Quick Reference Guide The NI Signal Generators Getting Started Guide provides instructions for installing and configuring NI signal generators. The NI Signal Generators Help includes detailed information about the NI PXI-5422 and the NI-FGEN functions. Yo
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3. Select the device that you want to calibrate. 4. Initiate self-calibration in one of the following ways: Click Self-Calibrate in the upper right corner. Right-click the device name under Devices and Interfaces, and select Self-Calibrate from the drop-down menu. FGEN Soft Front Panel To initiate self-calibration from the FGEN SFP, complete the following steps: 1. Select the device that you want to calibrate using the Device Configuration dialog box (Edit»Device Configuration). 2. Open th
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External Calibration Options External calibration involves both verification and adjustment. Verification is the process of testing the device to ensure that the output accuracy is within certain specifications. You can use verification to ensure that the adjustment process was successful or to determine if the adjustment process needs to be performed. Adjustment is the process of measuring and compensating for device performance to improve the output accuracy. Performing an adjustment upd
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Self-Calibrate Document Pre-Adjustment Verify Results Adjust (Cal Dates and Temperatures Updated) Document Post-Adjustment Verify Results Meets Yes No Calibration Test Limits? Review Verification/ Calibration/ Adjustment Verification Procedure or Complete Return Device Figure 1. Complete Calibration Programming Flow © National Instruments Corporation 9 NI PXI-5422 Calibration Procedure
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Optional Calibration You can choose to skip the adjustment steps of the calibration procedure if the output error is within the calibration test limits or the published specifications during the first verification. If all of the output errors determined during the first verification fall within the calibration test limits, the device is guaranteed to meet or exceed its published specifications for a full calibration interval. In this case, you can update the calibration date, effectively r
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Self-Calibrate Document Pre-Adjustment Verify Results Meets Yes No Calibration Test Limits? Meets Yes Published No Specifications? Results Update Calibration Within Dates and Published Specs Temperatures (Adjustment Without Adjusting Optional) Adjust (Cal Dates and No Adjust Yes Temperatures Anyway? Updated) Document Verify Post-Adjustment Results Meets Calibration/ Yes No Calibration Verification Test Limits? Complete Review Verification/ Adjustment Procedure or Return Device Figure 2. Opti
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External Calibration Requirements This section describes the test equipment and test conditions required for calibration. Test Equipment External calibration requires different equipment for each applicable specification. Refer to Table 2 for a list of equipment. Table 2. Equipment Required for Calibrating the NI PXI-5422 Applicable Minimum Recommended Instrument Specification Specifications Instrument Digital multimeter DC gain and offset DC accuracy ≤ ±50 ppm NI PXI-4070 (DMM) Resolution
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External Calibration Procedures The complete external calibration procedure consists of self-calibrating, verifying the performance of the NI PXI-5422, adjusting the calibration constants, and verifying again after the adjustments. In some cases, the complete calibration procedure may not be required. Refer to the External Calibration Options section for more information. The external calibration procedure automatically stores the calibration date to allow traceability. Writing Your Cali
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Verifying NI PXI-5422 Specifications Note Always self-calibrate the NI PXI-5422 before beginning a verification procedure. This section provides instructions for verifying the NI PXI-5422 specifications. This section also includes instructions for updating the calibration cycle. Verification determines whether the device is performing within its specifications prior to external adjustment. Verification and external adjustment together comprise a complete calibration. To verify that the NI
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NI PXI-5422 16-Bit 200 MS/s AWG ACCESS ACTIVE CH 0 CLK IN PFI 0 PFI 1 Figure 3. NI PXI-5422 Front Panel Connectors © National Instruments Corporation 15 NI PXI-5422 Calibration Procedure DIGITAL DATA & CONTROL
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Verifying the Oscillator Frequency Accuracy This test verifies the frequency accuracy of the oscillator on the NI PXI-5422. The verification involves generating a 10 MHz sine wave with the NI PXI-5422 and measuring the sine wave frequency with one of the instruments from Table 2. To verify the frequency accuracy of the oscillator on the NI PXI-5422, complete the following steps: 1. Connect the NI PXI-5422 CH 0 front panel connector to the instrument measuring the frequency accuracy with a m
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5. Call niFgen_SetAttributeViReal64 to set the offset (niFgen property node: Arbitrary Waveform Output»Arbitrary Waveform Offset) using the following parameters: vi: The session handle returned from niFgen_init channelName: "0" attributeID: NIFGEN_ATTR_ARB_OFFSET value: 0 Note You can adjust this value based on which measuring device you use. 6. Call niFgen_SetAttributeViBoolean to set the analog filter state (niFgen property node: Output Attributes»Analog Filter Enabled) using the
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A frequency error of 45 Hz for a 10 MHz signal corresponds to an error of 4.5 ppm. This limit accounts for the initial accuracy and the frequency deviation caused by temperature and aging. Refer to Table 3 for frequency ranges. Table 3. Frequency Ranges Calibration Test Limit Published Specifications ±25 ppm Low High Low High 9,999,955 Hz 10,000,045 Hz 9,999,750 Hz 10,000,250 Hz 11. Call niFgen_AbortGeneration (niFgen Abort Generation VI) to abort the waveform generation using the following
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IDQuery: VI_TRUE resetDevice: VI_TRUE vi: A pointer to a ViSession. The variable passed by reference through this parameter receives the value that identifies the session created by this function. This value acts as the session handle and is passed as the first parameter to all subsequent NI-FGEN functions. 3. Call niFgen_SetAttributeViBoolean to set the analog filter state (niFgen property node: Output Attributes»Analog Filter Enabled) using the following parameters: vi: The sessi
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7. Call niFgen_SetAttributeViBoolean to enable the analog output (niFgen property node: Basic Operation»Output Enabled) using the following parameters: vi: The session handle returned from niFgen_init channelName: "0" attributeID: NIFGEN_ATTR_OUTPUT_ENABLED value: VI_TRUE 8. Create an array of waveform samples for the positive full-scale DC waveform. This array should contain 500 samples with each sample having the value 1.0 (representation: double). 9. Call niFgen_CreateArbWaveform
