National Instruments NI 5421 Calibration Procedure
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National Instruments NI 5421 Calibration Procedure

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CALIBRATION PROCEDURE
NI 5421/5441
Contents
Conventions ............................................................................................ 2
Introduction ............................................................................................. 3
Software and Documentation Requirements........................................... 3
Software ........................................................................................... 3
Documentation................................................................................. 5
Self-Calibration Procedures .................................................................... 5
MAX ................................................................................................ 5
FGEN Soft Front Panel.................................................................... 6
NI-FGEN ......................................................................................... 6
External Calibration Options .................................................................. 7
Complete Calibration ....................................................................... 8
Optional Calibration ........................................................................ 9
External Calibration Requirements......................................................... 11
Test Equipment ................................................................................ 11
Test Conditions ................................................................................ 11
External Calibration Procedures ............................................................. 12
Writing Your Calibration Procedure................................................ 12
Calibration Procedures in LabVIEW........................................ 12
Calibration Procedures in LabWindows/CVI........................... 12
Calibration Procedures in C...................................................... 12
Verifying NI 5421/5441 Specifications ........................................... 13
Verifying the Oscillator Frequency Accuracy.......................... 15
Verifying the DC Gain and Offset Accuracy ........................... 18
Verifying the Main Analog Path Gain............................... 18
Verifying the Main Analog Path Offset ............................ 23
Verifying the Gain of the Direct Path ............................... 26
Adjusting the NI 5421/5441 ............................................................ 29
Initializing the External Calibration Session ............................ 32

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  • Page 1: Table Of Contents

    Calibration Procedures in LabVIEW........12 Calibration Procedures in LabWindows/CVI......12 Calibration Procedures in C............12 Verifying NI 5421/5441 Specifications ........... 13 Verifying the Oscillator Frequency Accuracy......15 Verifying the DC Gain and Offset Accuracy ......18 Verifying the Main Analog Path Gain....... 18 Verifying the Main Analog Path Offset ......

  • Page 2: Conventions

    This font is also used for the proper names of disk drives, paths, directories, programs, subprograms, subroutines, device names, functions, operations, variables, filenames, and extensions. NI 5421/5441 Calibration Procedure ni.com...

  • Page 3: Introduction

    This section describes the software and documentation required for both self-calibration and external calibration. Software Calibrating the NI 5421 requires installing NI-FGEN version 2.0 or later on the calibration system. Calibrating the NI 5441 requires installing NI-FGEN version 2.3 or later on the calibration system. You can download NI-FGEN from the Instrument Driver Network at ni.com/idnet...
  • Page 4 Contains the function panels for the functions IVI\Drivers\niFgen\niFgen.fpl in the (CVI) niFgen_32.dll The calibration process is described in the Self-Calibration Procedures External Calibration Procedures sections, including step-by-step instructions on calling the appropriate calibration functions. NI 5421/5441 Calibration Procedure ni.com...

  • Page 5: Documentation

    NI signal generators. The NI Signal Generators Help includes detailed information about the NI 5421/5441 and the NI-FGEN functions. You can access this help file by selecting Start»Programs»National Instruments»NI-FGEN» Documentation»NI Signal Generators Help. For the latest versions of NI documentation, refer to ni.com/manuals...

  • Page 6: Fgen Soft Front Panel

    Select the device that you want to calibrate using the Device Configuration dialog box (Edit»Device Configuration). Open the Calibration dialog box (Utility»Calibration). Click Perform self-calibration. NI-FGEN To self-calibrate the NI 5421/5441 programmatically using NI-FGEN, complete the following steps: Call (niFgen Initialize VI) to open an NI-FGEN session niFgen_init using the following parameters: •...

  • Page 7: External Calibration Options

    Complete Calibration section describes the recommended calibration procedure. The Optional Calibration section describes alternative procedures that allow you to skip adjustment if the device already meets its calibration test limits or published specifications. © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 8: Complete Calibration

    Complete Calibration Performing a complete calibration is the recommended way to guarantee that the NI 5421/5441 meets or exceeds its published specifications for a two-year calibration interval. At the end of the complete calibration procedure, you verify that the output error falls within the calibration test limits.

  • Page 9: Optional Calibration

    In this case, you can update the calibration date, effectively resetting the calibration interval, without actually performing an adjustment. Refer to the Adjusting the NI 5421/5441 section for more information. If all of the output errors determined during the first verification fall within the published specifications, but not within the calibration test limits, adjustment is also optional.
  • Page 10 Without Adjusting Optional) Adjust (Cal Dates and Adjust Temperatures Anyway? Updated) Document Verify Post-Adjustment Results Meets Calibration/ Calibration Verification Test Limits? Complete Review Verification/ Adjustment Procedure or Return Device Figure 2. Optional Calibration Programming Flow NI 5421/5441 Calibration Procedure ni.com...

  • Page 11: 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 5421/5441 Applicable Minimum Recommended Instrument...

  • Page 12: External Calibration Procedures

    External Calibration Procedures The complete external calibration procedure consists of self-calibrating, verifying the performance of the NI 5421/5441, adjusting the calibration constants, and verifying again after the adjustments. In some cases, the complete calibration procedure may not be required. Refer to the...

  • Page 13: Verifying Ni 5421/5441 Specifications

    If any of these tests fail immediately after you perform an external adjustment, verify Note that you have met the required test conditions before you return the NI 5421/5441 to NI for repair. Refer to Table 2 for information about which instrument to use for verifying each specification.
  • Page 14 NI PCI-5421 ACCESS ACTIVE CH 0 PFI 0 PFI 1 Figure 3. NI PXI-5421/5441 and NI PCI-5421 Front Panel Connectors NI 5421/5441 Calibration Procedure ni.com...

  • Page 15: Verifying The Oscillator Frequency Accuracy

    This test verifies the frequency accuracy of the oscillator on the NI 5421/5441. The verification involves generating a 10 MHz sine wave with the NI 5421/5441 and measuring the sine wave frequency with one of the instruments from Table 2.
  • Page 16 Because you set the sample rate to 100 MS/s and because you are using 10 samples per cycle, the resulting waveform is a 10 MHz sine wave. The sample values of this waveform must fall between –1.0 and 1.0. Note NI 5421/5441 Calibration Procedure ni.com...
  • Page 17 The session handle returned from niFgen_init 12. Measure the frequency out of the NI 5421/5441. 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.

  • Page 18: Verifying The Dc Gain And Offset Accuracy

    Verifying the DC Gain and Offset Accuracy This test verifies the DC gain and offset accuracy of the NI 5421/5441 into a high-impedance load by generating a number of DC voltages and offsets, measuring the voltage with a DMM, and comparing the NI 5421/5441 to the error limits.
  • Page 19 • attributeID: NIFGEN_ATTR_OUTPUT_ENABLED • value: VI_TRUE 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 (representation: double). © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 20 The session handle returned from niFgen_init • channelName: "0" • attributeID: NIFGEN_ATTR_ARB_OFFSET • value: Repeat steps 13 through 23 for each of the 24 iterations listed in Table 4, changing the Gain value for each iteration. NI 5421/5441 Calibration Procedure ni.com...
  • Page 21 – 0.006500 ±0.000510 ±0.000526 Note: Error Positive Full-Scale Value = (Measured Positive Full-Scale Value) – (Ideal Positive Full-Scale Value) Error Negative Full-Scale Value = (Measured Negative Full-Scale Value) – (Ideal Negative Full-Scale Value) © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 22: To Set The Gain

    • vi: The session handle returned from niFgen_init 16. Measure the DC voltage out of the NI 5421/5441. This is the Measured Positive Full-Scale Value. 17. Determine the error for positive full scale using the following forumla: Error Positive Full-Scale = (Measured Positive Full-Scale Value) –...

  • Page 23: Verifying The Main Analog Path Offset

    21. Measure the DC voltage out of the NI 5421/5441. This is the Measured Negative Full-Scale Value. 22. Determine the error for negative full scale using the following formula: Error Negative Full-Scale = (Measured Negative Full-Scale Value) – (Ideal Negative Full-Scale Value) Compare this error to the Published Spec or the Calibration Test Limit.
  • Page 24 0.006500 0.003250 – 0.003250 ±0.000511 ±0.000528 Note: Error Positive Offset Value = (Measured Positive Offset Value) – (Ideal Positive Offset Value) Error Negative Offset Value = (Measured Negative Offset Value) – (Ideal Negative Offset Value) NI 5421/5441 Calibration Procedure ni.com...
  • Page 25 • vi: The session handle returned from niFgen_init Measure the positive DC voltage out of the NI 5421/5441. This is the Measured Positive Offset Value. Determine the error for positive offset using the following formula: Error Positive Offset = (Measured Positive Offset Value) –...

  • Page 26: Verifying The Gain Of The Direct Path

    • vi: The session handle returned from niFgen_init 12. Measure the negative DC voltage out of the NI 5421/5441. This is the Measured Negative Offset Value. 13. Determine the error for negative offset using the following formula: Error Negative Offset = (Measured Negative Offset Value) –...

  • Page 27: Nifgen_Init

    • vi: The session handle returned from niFgen_init Measure the positive DC voltage out of the NI 5421/5441. This is the Measured Positive Full-Scale Value. © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 28 • vi: The session handle returned from niFgen_init 10. Measure the negative DC voltage out of the NI 5421/5441. This is the Measured Negative Full-Scale Value. 11. Call (niFgen Abort Generation VI) to...

  • Page 29: Adjusting The Ni 5421/5441

    If the NI 5421/5441 is not within the calibration test limits for each verification procedure, perform the adjustment procedure to improve the accuracy of the NI 5421/5441.
  • Page 30 NI-FGEN uses these calibration constants during a standard NI-FGEN session to ensure that the device operates within its specifications. You must close an external calibration session by using (niFgen Close Ext Cal VI), as shown in Figure 4. niFgen_CloseExtCal NI 5421/5441 Calibration Procedure ni.com...
  • Page 31 Gain and Offset Adjust Direct Path Gain Initialize Oscillator Frequency Calibration Adjust Oscillator Frequency Initialize Calibration ADC Calibration Adjust Calibration ADC Close Ext Cal Session Figure 4. NI 5421/5441 External Calibration Procedure © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 32: Initializing The External Calibration Session

    The session handle returned from niFgen_InitExtCal Call (niFgen Write niFgen_WriteBinary16AnalogStaticValue Binary 16 Analog Static Value VI) to set the main DAC value using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • value: NI 5421/5441 Calibration Procedure ni.com...
  • Page 33 Call to set the pre-amplifier niFgen_SetAttributeViReal64 attenuation (niFgen property node: Calibration»Pre-Amplifier Attenuation) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_PRE_AMPLIFIER_ATTENUATION • value: © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 34: Adjusting The Main Path Pre-Amplifier Offset

    Call to set the analog path value niFgen_SetAttributeViInt32 (niFgen property node: Output Attributes»Analog Path) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_ANALOG_PATH • value: NIFGEN_VAL_FIXED_LOW_GAIN_ANALOG_PATH NI 5421/5441 Calibration Procedure ni.com...
  • Page 35 Table 7. Attributes and Values for Main Path Pre-Amplifier Offset Analog Filter Pre-Amplifier Iteration Enable Attenuation Current Configuration VI_FALSE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_OFF_0DB VI_FALSE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_OFF_3DB VI_FALSE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_OFF_6DB VI_FALSE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_OFF_9DB VI_FALSE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_OFF_12DB VI_TRUE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_ON_0DB VI_TRUE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_ON_3DB VI_TRUE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_ON_6DB VI_TRUE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_ON_9DB VI_TRUE NIFGEN_VAL_CAL_CONFIG_MAIN_PATH_FILTER_ON_12DB © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 36 NIFGEN_ATTR_PRE_AMPLIFIER_ATTENUATION • value: The Pre-Amplifier Attenuation value for the current iteration from Table 7 Take the following voltage measurements at the NI 5421/5441 CH 0 front panel connector into a high-impedance load: Call to set the gain DAC value niFgen_SetAttributeViInt32 (niFgen property node: Calibration»Gain DAC Value) using the...
  • Page 37 Wait 500 ms for the output to settle. m. Use the DMM to measure the voltage output of the device. This measurement is , which is used in step 8. measurement 2 © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 38: Adjusting The Main Path Pre-Amplifier Gain

    • value: NIFGEN_VAL_FIXED_LOW_GAIN_ANALOG_PATH Call to set the post-amplifier niFgen_SetAttributeViReal64 attenuation (niFgen property node: Calibration»Post-Amplifier Attenuation) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_POST_AMPLIFIER_ATTENUATION • value: NI 5421/5441 Calibration Procedure ni.com...
  • Page 39 • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_ANALOG_FILTER_ENABLED • value: The Analog Filter Enable value for the current iteration from Table 8 © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 40 NIFGEN_ATTR_PRE_AMPLIFIER_ATTENUATION • value: The Pre-Amplifier Attenuation value for the current iteration from Table 8 Take the following voltage measurements at the NI 5421/5441 CH 0 front panel connector into a high-impedance load: Call to set the gain DAC value niFgen_SetAttributeViInt32 (niFgen property node: Calibration»Gain DAC Value) using...
  • Page 41 ) that you set for the offset DAC 32000 • measuredOutputs: An array containing two elements—the two output voltages ( ) that measurement 0 measurement 1 you measured—in the order that you measured them © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 42: Adjusting The Main Path Post-Amplifier Gain And Offset

    "0" • attributeID: NIFGEN_ATTR_GAIN_DAC_VALUE • value: 2000 Repeat steps 5 through 8 for each of the eight iterations listed in Table 9, changing the Analog Path, Post-Amplifier Attenuation, and Current Configuration values for each iteration. NI 5421/5441 Calibration Procedure ni.com...
  • Page 43 Attenuation) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_POST_AMPLIFIER_ATTENUATION • value: The Post-Amplifier Attenuation value for the current iteration from Table 9 © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 44 Take the following voltage measurements at the NI 5421/5441 CH 0 front panel connector into a high-impedance load: Call to set the offset DAC niFgen_SetAttributeViInt32 value (niFgen property node: Calibration»Offset DAC Value) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal •...

  • Page 45: Adjusting The Direct Path Gain

    DAC value niFgen_SetAttributeViInt32 (niFgen property node: Calibration»Offset DAC Value) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_OFFSET_DAC_VALUE • value: 32767 © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 46 Call to enable the analog output niFgen_SetAttributeViBoolean (niFgen property node: Basic Operation»Output Enabled) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_OUTPUT_ENABLED • value: VI_TRUE NI 5421/5441 Calibration Procedure ni.com...
  • Page 47 • vi: The session handle returned from niFgen_InitExtCal 11. Take the following voltage measurements at the NI 5421/5441 CH 0 front panel connector into a high-impedance load: Call (niFgen niFgen_WriteBinary16AnalogStaticValue Write Binary 16 Analog Static Value VI) to set the main DAC value using the following parameters: •...
  • Page 48 The session handle returned from niFgen_InitExtCal Wait 500 ms for the output to settle. Use the DMM to measure the voltage output by the device. This measurement is , which is used in step 12. measurement 3 NI 5421/5441 Calibration Procedure ni.com...

  • Page 49: Adjusting The Oscillator Frequency

    Gain) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_ARB_GAIN • value: You can adjust this value based on which measuring device you use. Note © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 50 • value: Call to set the output impedance niFgen_SetAttributeViReal64 (niFgen property node: Basic Operation»Output Impedance) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_OUTPUT_IMPEDANCE • value: NI 5421/5441 Calibration Procedure ni.com...
  • Page 51 , which is used in step 15. measured frequency 15. Repeat steps 15a through 15d for as long as the difference between the measured frequency and the desired frequency (10 MHz) is greater than the tolerance (4.5 ppm). © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 52: Adjusting The Calibration Adc

    The session handle returned from niFgen_InitExtCal Adjusting the Calibration ADC The NI 5421/5441 has an onboard calibration ADC that is used during self-calibration. Adjusting the calibration ADC involves characterizing the gain and offset associated with this ADC so that performing self-calibration results in an accurately calibrated device.
  • Page 53 Call to set the pre-amplifier niFgen_SetAttributeViReal64 attenuation (niFgen property node: Calibration»Pre-Amplifier Attenuation) using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • attributeID: NIFGEN_ATTR_PRE_AMPLIFIER_ATTENUATION • value: © National Instruments Corporation NI 5421/5441 Calibration Procedure...
  • Page 54 14. Call (niFgen Write niFgen_WriteBinary16AnalogStaticValue Binary 16 Analog Static Value VI) to set the main DAC value using the following parameters: • vi: The session handle returned from niFgen_InitExtCal • channelName: "0" • value: 27232 NI 5421/5441 Calibration Procedure ni.com...
  • Page 55 The session handle returned from niFgen_InitExtCal 21. Wait 500 ms for the output to settle. 22. Use the DMM to measure the NI 5421/5441 voltage output directly into the DMM into a high-impedance load. This measurement is , which is used in step 32.
  • Page 56 • channelName: "0" • attributeID: NIFGEN_ATTR_OUTPUT_ENABLED • value: VI_TRUE 29. Call (niFgen Commit VI) to commit the attribute niFgen_Commit values to the device using the following parameter: • vi: The session handle returned from niFgen_InitExtCal NI 5421/5441 Calibration Procedure ni.com...

  • Page 57: Closing The External Adjustment Session

    30. Wait 500 ms for the output to settle. 31. Use the DMM to measure the NI 5421/5441 voltage output directly into the DMM (into a high-impedance load). This measurement is , which is used in step 32. external measurement 1 32.

  • Page 58: Calibration Utilities

    Calibration Utilities NI-FGEN supports several calibration utilities that allow you to retrieve information about adjustments performed on the NI 5421/5441, restore an external calibration, change the external calibration password, and store small amounts of information in the onboard EEPROM. You can retrieve some data using MAX or the FGEN SFP;...

  • Page 59: Ni-Fgen

    VIs. Refer to the NI Signal Generators Help for the complete function reference. The utility functions include: • niFgen_RestoreLastExtCalConstants • niFgen_GetSelfCalSupported • niFgen_GetSelfCalLastDateAndTime • niFgen_GetExtCalLastDateAndTime • niFgen_GetSelfCalLastTemp • niFgen_GetExtCalLastTemp • niFgen_GetExtCalRecommendedInterval • niFgen_ChangeExtCalPassword • niFgen_SetCalUserDefinedInfo • niFgen_GetCalUserDefinedInfo • niFgen_GetCalUserDefinedInfoMaxSize © National Instruments Corporation NI 5421/5441 Calibration Procedure...

  • Page 60: Where To Go For Support

    Instruments trademarks. Other product and company names mentioned herein are trademarks or trade names of their respective companies. For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txt file on your CD, or ni.com/patents.

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