National Instruments PXIe-4468 Manual

PXIe-4468

September 2022
PXIe-4468
Calibration procedure

ni.com/services
PXIe-4468 Calibration Procedure

PXIe-4468 Calibration Procedure
2ni.com/services
This document contains the verification and adjustment procedures for the
PXIe-4468 with either BNC or mini-XLR connectors. Use the procedures in this
document to automate calibration or to conduct manual calibration. Review
and become familiar with the entire procedure before beginning the
calibration process.
Contents
Terms and Definitions...............................................................................................3
Calibration Overview.................................................................................................4
Calibration Condition Guidelines .........................................................................5
Calibration Resources...............................................................................................5
Required Software.................................................................................................5
Recommended Documentation...........................................................................6
Test Equipment .....................................................................................................6
Warm Up the DUT......................................................................................................8
Perform Self-Calibration.......................................................................................8
Perform Verification..................................................................................................9
AI Offset Accuracy Verification..............................................................................9
AI Gain Accuracy Verification ..............................................................................12
AI Gain Flatness Verification ...............................................................................14
IEPE Current Verification.....................................................................................17
AO Differential Offset Accuracy Verification.......................................................19
AO Differential Gain Accuracy Verification.........................................................22
AO Gain Flatness Verification..............................................................................26
AO Common-Mode Gain and Offset Verification ...............................................29
Timebase Frequency Accuracy Verification.......................................................31
Perform Adjustment................................................................................................34
AI/AO Gain and Offset Adjustment .....................................................................34
Timebase Adjustment .........................................................................................35
Perform Reverification............................................................................................36
Update the Onboard Calibration Information.......................................................37
Revision History.......................................................................................................37
NI Services ...............................................................................................................38

PXIe-4468 Calibration Procedure
© National Instruments Corporation 3
Terms and Definitions
DUT DUT is an acronym for Device Under Test and refers to the NI product
being calibrated. For this procedure, DUT refers to the PXIe-4468.
As-Found Limits These limits are derived from the published specifications for the DUT.
NI uses these limits to determine if the DUT is performing within the
recommended calibration interval specifications at the time of
calibration and before any adjustment is performed.
As-Left Limits These limits are derived from the published specifications for the DUT
minus guardband to ensure a high probability that the DUT will meet its
specifications over the next recommended calibration interval.
Functional Test Functional Tests determine whether the DUT is operating correctly.
Functional tests are not directly related to performance specifications.
Verification Verification evaluates the measured calibration results against the
defined As-Found Limits. The result of the evaluation is expressed as a
Pass/Fail condition in the calibration certificate using an established
evaluation formula.
Adjustment Adjustment performs a set of operations on the DUT to optimize the
measurement performance and conform it to the assigned calibrated
values.
Reverification Reverification evaluates the measured calibration results against the
As-Left limits after adjustment. The As-Left limits may be tighter than
the As-Found limits.
Recommended
Calibration Interval
This interval indicates the recommended period between each round of
verification and adjustment of the DUT. There is a high probability that,
within this interval, the DUT will remain within the published warranted
performance specifications. Some measurement DUTs have warranted
specifications for different calibration intervals, for example: 24 hours,
90 days, 1 year, and 2 years. In this case, the specification depends on
the calibration cycle chosen by the user.

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Calibration Overview
Recommended Calibration Interval
2 years
Password
NI
Note
This is the default password for all password-protected operations.
This password is site-specific.
Task Estimated Test
Time
Operator
Connections Test Points
Setup 10 minutes — —
Warm Up 15 minutes — —
Verify, Adjust, and
Reverify
19 minutes 36 344
Verify Only 8 minutes 17 171
Adjust Only 3 minutes 2 2
Note
Estimated test times assume the user is conducting a manual
calibration. For most procedures, automating the calibration
significantly reduces test times.
Environmental Conditions Verification Adjustment
Ambient temperature 23 °C ± 5 °C 23 °C ± 5 °C
Internal DUT temperature range Tcal ±5 °C Tcal ±5 °C
Relative humidity Between 20% and 80%, noncondensing

PXIe-4468 Calibration Procedure
© National Instruments Corporation 5
Calibration Condition Guidelines
Keep cabling as short as possible. Long cables act as antennas, picking
up extra noise that can affect measurements.
Ensure that all connections to the DUT are secure.
Allow adequate warm up time for all components of the calibration
system.
Make all connections as shown in diagrams.
Use shielded copper wire for all cable connections to the DUT.
Use twisted-pair wires to eliminate noise and thermal offsets.
Ensure that the PXI/PXI Express chassis fan speed is set to HIGH, that the
fan filters are clean, and that the empty slots contain filler panels. For
more information, refer to the Maintain Forced-Air Cooling Note to Users
document available at ni.com/manuals.
If a DUT fails reverification after adjustment, ensure that the Test
Conditions have been met before returning the DUT to NI.
If the coupling changes from DC to AC (for example, on the first gain
verification point tested), commit the configuration using the DAQmx
Control Task VI and wait 5 seconds for the input to settle. Subsequent
gain verification points, which do not change the coupling, do not
require a delay.
Calibration Resources
Required Software
Note
Ensure that the most recent version of the required driver software is
installed before conducting the calibration.

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Install the following software on the calibration system:
DAQmx
Recommended Documentation
Go to ni.com/docs to locate the following documentation for more
information when performing this calibration:
PXIe-4468 Getting Started Guide
PXIe-4468 Specifications
NI-DAQmx Readme
NI-DAQmx Help
LabVIEW Help
NI-DAQmx C Reference Help
NI-DAQmx .NET Help Support for Visual Studio
Test Equipment
This section details the equipment NI recommends for each test performed
as part of this calibration procedure.
NI Calibration Executive Users
Refer to the Calibration Executive Help to find an updated list of test
equipment for this calibration procedure.

PXIe-4468 Calibration Procedure
© National Instruments Corporation 7
Standard Recommended
Model Where Used Functional Requirement(s)
Calibrator Fluke 5730A AI Gain
AI Flatness
Frequency Range:
40 Hz to 100 kHz
Voltage Range: up to
6.3 Vrms
Digital Multimeter
(DMM)
Keysight (Agilent)
3458A
AO Differential Offset
AO Differential Offset
and Gain Adjustment
DC Voltage
Input Range: 100mV,
1 V, 10 V
AO Differential Gain
AO Differential
Flatness
AC Voltage
Input Range: 1 Vrms,
10 Vrms
Frequency Range:
20Hz to 100 kHz
Function Generator Keysight (Agilent)
33250A series
Timebase Frequency Frequency Range: up
to 90 kHz
PXI Express Chassis NI PXIe-1082
NI PXIe-1085
NI PXIe-1075
NI PXIe-1065
NI PXIe-1062Q
All Tests
System Controller NI PXIe-8135 All Tests A PXI Express
controller or MXI
Express Card
mXLR (F) to BNC (M)
Cable (quantity 1)
NI 140150-0R46 All Tests (mXLR
Variant)
Length: ≤ 0.5m
BNC (M) to BNC (M)
Cable (quantity 1)
Pomona Electronics
5697
All Tests (BNC
Variant)
Length: ≤ 0.5m
BNC (F) to Banana
Adapter (quantity 1)
Pomona Electronics
1269
AI Gain
AI Flatness
AO Offset
AO Gain
AO Flatness
AO Offset and Gain
Adjustment

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Banana to Banana
Cable (quantity 1)
Pomona Electronics
B-4-2
AO Differential Gain
and Offset
Length: ≤ 0.5m
Banana to Alligator
Clip Cable (quantity 2)
Pomona Electronics
1166-12-0 (Black)
1166-12-2 (Red)
AO Differential Gain
and Offset
Length: ≤ 0.5m
Warm Up the DUT
Warm up time starts after the installed DUT is powered on in the chassis.
Warm up time resets after the DUT is removed from the chassis. This DUT
requires 15 minutes to warm up prior to conducting any tests.
Note
Observe adequate Warm up time for all components of the calibration
system.
Perform Self-Calibration
Self-calibration should be performed after the DUT has warmed up for the
recommended time period. This function measures the onboard reference
voltage of the DUT and adjusts the self-calibration constants to account for
any errors caused by short-term fluctuations in the environment.
Complete the following steps to conduct self-calibration using Measurement
& Automation Explorer (MAX).
Note
Disconnect all external signals before beginning self-calibration.
1. Launch MAX.
2. Select My System»Devices and Interfaces»NI PXIe-4468.
3. Start self-calibration using one of the following methods:
4. Click Self-Calibrate in the upper right corner of MAX.

PXIe-4468 Calibration Procedure
© National Instruments Corporation 9
5. Right-click the name of the DUT in the MAX configuration tree and
select Self-Calibrate from the drop-down menu.
Perform Verification
AI Offset Accuracy Verification
Test Limits
Table 1: AI Offset Verification Limits
Device
Gain (dB)
As-Found Test Limit As-Left Test Limit
Lower Limit
(mV)
Upper Limit
(mV)
Lower Limit
(mV)
Upper Limit
(mV)
DC Coupled
-20 -5.0 5.0 -0.9 0.9
-10 -2.0 2.0 -0.3 0.3
0 -0.5 0.5 -0.1 0.1
10 -0.2 0.2 -0.05 0.05
20 -0.1 0.1 -0.04 0.04
30 -0.1 0.1 -0.04 0.04
Initial Test Connection

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Figure 1. Initial Connection for AI Offset-BNC
1.
Calibrator
3.
BNC
– BNC Cable
2.
Banana
– BNC Adapter
4.
PXIe
-4468 with BNC
Figure 2. Initial Connection for AI Offset-mXLR
1.
Calibrator
3.
BNC
– mXLR Cable
2.
Banana
– BNC Adapter
4.
PXIe
-4468 with mXLR
Verification Procedure
Complete the following procedure to verify the AI offset accuracy.
Repeat 2 times, once for each channel.
1. Connect the AI channel under test to the Calibrator as shown in
Figure 1 or Figure 2.

PXIe-4468 Calibration Procedure
© National Instruments Corporation 11
2. Configure the calibrator to output 0V DC, with GND engaged.
Repeat 6 times, once for each gain setting.
3. Create and configure an AI voltage task on the DUT as shown in
Table 2.
Table 2: AI Offset Verification Configuration
Configuration Value
Physical channels Dev_name/aix
Gain* Gain from Table 1
Coupling DC
Terminal configuration Pseudodifferential
Excitation (IEPE) 0 (A)
Acquisition mode Finite number of samples
Rate 250000
Samples per channel 125000
*
As you configure the AI voltage task, refer to Table 3for the maximum and minimum
voltages to specify when creating the task to ensure the specified gain range is used on
the module. The module
automatically selects the gain range based on the maximum and mini
voltages you supply when you create the task.
Table 3: Gain Range and Corresponding Max and Min Voltages
Desired Gain Range (dB) Max Voltage (V) Min Voltage (V)
-20 42.4 -42.4
-10 31.6 -31.6
0 10.0 -10.0
10 3.16 -3.16
20 1.00 -1.00

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30 0.316 -0.316
4. Start the task.
5. Acquire readings with the DUT.
6. On a per channel basis, average all of the acquired samples.
7. Stop and clear the task.
8. Compare the averaged values to the appropriate limits in Table 1.
The average is the offset at the tested gain setting.
AI Gain Accuracy Verification
Test Limits
Table 4: AI Gain Verification Limits
Device
Gain (dB)
Calibrator Output As-Found Test Limit As-Left Test Limit
Amplitude
(Vrms)
Frequency
(Hz)
Lower
Limit
(Vrms)
Upper
Limit
(Vrms)
Lower
Limit
(Vrms)
Upper
Limit
(Vrms)
-20 6.3 1000 6.28189 6.31816 6.28551 6.31452
-10 6.3 1000 6.28189 6.31816 6.28551 6.31452
0 6.3 1000 6.28189 6.31816 6.29637 6.30363
10 2.0 1000 1.99425 2.00576 1.99885 2.00115
20 0.63 1000 0.62819 0.63182 0.62964 0.63036
30 0.2 1000 0.19943 0.20058 0.19988 0.20012

PXIe-4468 Calibration Procedure
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Initial Test Connection
Note
Initial test connection is same as AI Offset, as shown in Figure 1or
Figure 2.
Verification Procedure
Complete the following procedure to verify the AI gain accuracy.
Repeat 2 times, once for each channel.
1. Connect the AI channel under test to the Calibrator as shown in
Figure 1 or Figure 2.
Repeat 6 times, once for each gain setting.
2. Configure the calibrator to generate an output with the amplitude
and frequency from Table 4.
3. Create and configure an AI Voltage channel task using the values in
Table 5.
Table 5: AI Gain Verification Configuration
Configuration Value
Physical Channels Dev_name/aix
Gain* Gain from Table 4
Coupling AC
Terminal Configuration Pseudodifferential
Excitation (IEPE) 0 (A)
Acquisition mode Finite number of samples

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Rate 250000
Samples per channel 125000
*Refer to Table 3for the maximum and minimum voltages to specify to ensure the
specified gain range is used on the module.
4. Start the task.
5. Acquire readings with the DUT.
6. Calculate the RMS amplitude of the acquired fundamental harmonic.
Compare this amplitude to the appropriate voltage limits in Table 4.
The calculated amplitude is used to verify the gain accuracy of the
channel under test at the tested gain setting.
As an example, use the Extract Single Tone Information VI to help
calculate RMS. Note that the output of this VI is peak amplitude, and
must be divided by √2 to convert to RMS.
7. Stop and clear the task.
AI Gain Flatness Verification
Test Limits
Table 6: AI Flatness Verification Limits
Device Gain (dB)
Calibrator
Output
Frequency (kHz)
As-Found Test Limit
Lower Limit Upper Limit
-10 and -20
1 V1kHz
20 0.97724 * V1kHz 1.02329 * V1kHz
45 0.93325 * V1kHz 1.07152 * V1kHz
100 0.89125 * V1kHz 1.12202 * V1kHz
0, 10, 20 and 30 1 V1kHz

PXIe-4468 Calibration Procedure
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20 0.99931 * V1kHz 1.00069 * V1kHz
45 0.99713 * V1kHz 1.00288 * V1kHz
100 0.99083 * V1kHz 1.00925 * V1kHz
Initial Test Connection
Note
Initial test connection is same as AI Offset, as shown in Figure 1or
Figure 2.
Verification Procedure
Complete the following procedure to verify the AI flatness accuracy.
Repeat 2 times, once for each channel.
1. Connect the AI channel under test to the Calibrator as shown in Figure
1or Figure 2.
Repeat 6 times, once for each gain setting.
Repeat 4 times, once for each frequency in
Table 6
.
2. Configure the calibrator to generate an output with the frequency
listed in Table 6and amplitude listed in Table 7.
Table 7: AI Flatness Inputs
Device Gain (dB)
Configuration Value
Amplitude (Vrms) Frequency (Hz)
-20 6.3 1000
-10 6.3 1000
0 6.3 1000

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10 2.0 1000
20 0.63 1000
30 0.2 1000
3. Configure an AI Voltage channel task using the values in Table 8.
Table 8: AI Flatness Verification Configuration
Configuration Value
Physical channel Dev_name/aix
Gain* Gain from Table 6
Coupling AC
Terminal Configuration Pseudodifferential
Excitation (IEPE) 0 (A)
Acquisition mode Finite number of samples
Rate 250000
Samples Per Channel 125000
*Refer to Table 3for the maximum and minimum voltages to specify to ensure the specified
gain range is used on the module.
4. Start the task.
5. Acquire the readings with the DUT.
6. Calculate the RMS amplitude of the acquired fundamental
harmonic. The first measured amplitude represents V1kHz
referenced in Table 6. Subsequent test points will be calculated
based on V1kHz, as shown in Table 6.
As an example, use the Extract Single Tone Information VI to help
calculate the RMS. Note that the output of this VI is peak
amplitude, and it must be divided by √2 to convert to RMS.
7. Stop and clear the task.

PXIe-4468 Calibration Procedure
© National Instruments Corporation 17
IEPE Current Verification
Test Limits
Table 9: IEPE Current Limits
IEPE Current Setting
(mA)
As-Found Test Limit
Lower Limit (mA) Upper Limit (mA)
4 3.858 4.205
10 9.655 10.523
20 19.247 20.976
Initial Test Connection
Figure 3. Initial Connection for IEPE Current—BNC
1.
DMM
3.
BNC
– BNC Cable
2.
Banana
– BNC Adapter
4.
PXIe
-4468 with BNC

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Figure 4. Initial Connection for IEPE Current-mXLR
1.
DMM
3.
BNC
– mXLR Cable
2.
Banana
– BNC Adapter
4.
PXIe
-4468 with mXLR
Verification Procedure
Complete the following procedure to verify the IEPE current.
Repeat 2 times, once for each channel.
1. Connect the AI channel under test to the DMM as shown in Figure 3or
Figure 4.
Repeat 3 times, once for each IEPE current setting.
2. Set the DMM to the AMPS function and the 10 mA range for the 4 mA
and 10 mA test points, and the 100 mA range for the 20 mA test point.
3. Create and configure an AI Voltage task using the values in Table 10.
Table 10:IEPE Current Verification Configuration
Configuration Value
Physical Channels Dev_name/aix
Gain* -20 (dB)
Coupling AC