National Instruments NI 9775 Manual

CALIBRATION PROCEDURE
NI 9775
±10 V, 20 MS/s/ch, 14-Bit, 4-Channel C Series Digitizer Module
This document contains the verification and adjustment procedures for the NI 9775. For more
information on calibration, visit ni.com/calibration.
Software
Calibrating the NI 9775 requires the installation of NI-DAQmx 17.6 or later. You can
download NI-DAQmx from ni.com/downloads. NI-DAQmx supports LabVIEW,
LabWindows™/CVI™, C/C++, C#, and Visual Basic .NET. When you install NI-DAQmx, you
only need to install support for the application software that you intend to use.
Documentation
Consult the following documents for information about the NI 9775, NI-DAQmx, and your
application software. All documents are available on ni.com/manuals and help files install with
the software.
•NI cDAQ-9174/9178 USB Chassis Quick Start
•NI 9775 Datasheet
•NI 9775 Getting Started Guide
•NI-DAQmx Readme
•LabVIEW Help
•NI-DAQmx C Reference Help
•NI-DAQmx .NET Help Support for Visual Studio
Test Equipment
The following table lists the equipment recommended for the performance verification and
adjustment procedures. If the recommended equipment is not available, select a substitute
using the requirements.
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Table 1. Recommended Equipment
Equipment Recommended Model Requirements
Calibrator Fluke 5730A DC gain error <500 ppm, DC offset error <100 µV,
AC gain error <0.2%
Chassis cDAQ-9178 —
Test Conditions
The following setup and environmental conditions are required to ensure the NI 9775 meets
published specifications.
• Keep connections to the NI 9775 as short as possible. Long cables and wires act as
antennas, picking up extra noise that can affect measurements.
• Verify that all connections to the NI 9775 are secure.
• Maintain an ambient temperature of 23 °C ± 5 °C.
• Keep relative humidity below 80%.
• Allow a warm-up time of at least 15 minutes to ensure that the NI 9775 measurement
circuitry is at a stable operating temperature.
Initial Setup
Complete the following steps to set up the NI 9775.
1. Install NI-DAQmx.
2. Make sure the cDAQ-9178 power source is not connected.
3. Install the module in slot 8 of the cDAQ-9178 chassis. Leave slots 1 through 7 of the
cDAQ-9178 chassis empty.
4. Connect the cDAQ-9178 chassis to your host computer.
5. Connect the power source to the cDAQ-9178 chassis.
6. Launch Measurement & Automation Explorer (MAX).
7. Right-click the device name and select Self-Test to ensure that the module is working
properly.
Verification
The following performance verification procedure describes the sequence of operation and test
points required to verify the NI 9775 and assumes that adequate traceable uncertainties are
available for the calibration references.
AC Accuracy Verification
Complete the following procedure to determine the As-Found Status of AC Accuracy of the
NI 9775.
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1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9775 to the calibrator as shown in the following figure.
Figure 1. Connections for DC and AC Accuracy Verification and Adjustment
NI 9775
Calibrator
HI
LO
AI1
AI0
AI2
AI3
+
–
+
–
+
–
+
–
3. Set the calibrator to generate AC voltage with settings shown in the following table.
Table 2. Calibrator Configuration for AC Accuracy Verification
Output Function Amplitude (V RMS) Frequency
AC Voltage 2.00 50 kHz
4. Set the calibrator to Operate mode (OPR).
5. Acquire samples from the NI 9775 and extract 50 kHz amplitude information.
a) Create and configure an AI voltage task on the NI 9775 according to the following
table.
Table 3. NI 9775 AI Task Configuration for AC Accuracy Verification
Physical Channels Min (V) Max (V) Terminal Configuration Scaled Units
cDAQMod8/AI0:3 -10 10 RSE Volts
b) Configure the AI voltage task timing according to the following table.
Table 4. NI 9775 Timing Configuration for AC Accuracy Verification
Sample Mode Samples per Channel Rate
Finite Sample 40,000 20 MS/s
c) Configure the channel properties according to the following table.
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Table 5. NI 9775 Channel Properties Configuration for AC Accuracy Verification
AI.ADCTimingMode AI.Lowpass.Enable
High Speed False
d) Start the task.
e) Read the samples from the NI 9775.
f) Extract the amplitude of the 50 kHz signal from each channel. This can be done
using the "Extract Single Tone Information.vi". The output of the "Extract Single
Tone Information.vi" is in Vpk. To obtain AC amplitude error in units of dB, use the
following equation:
    = 20 × log 10

2 × 2.0
g) Clear the task.
6. Compare the amplitude error to the limits in the following table
Table 6. NI 9775 Verification Limits for AC Accuracy
Test Point 1-Year Limits
Frequency Amplitude (V RMS) Upper Limit Lower Limit
50 kHz 2.00 0.12 dB -0.12 dB
Note The test limits listed in this table are derived using the values in the
NI 9775 Accuracy Under Calibration Conditions table.
Note The uncertainty of the calibration standard is not included in these
limits.
7. Set the calibrator to Standby mode (STBY).
8. Disconnect the NI 9775 from the calibrator.
DC Accuracy Verification
Complete the following procedure to determine the As-Found status of DC Accuracy of the
NI 9775.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9775 to the calibrator as shown in the AC Accuracy Verification section.
3. Set the calibrator voltage to a Test Point value indicated in the NI 9775 Verification Limits
for DC Accuracy table.
4. Set the calibrator to Operate mode (OPR).
5. Acquire and average samples.
a) Create and configure an AI voltage task on the NI 9775 according to the following
table.
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Table 7. NI 9775 Configuration for DC Accuracy Verification
Physical Channels Min (V) Max (V) Terminal Configuration Scaled Units
cDAQMod8/AI0:3 -10 10 RSE Volts
b) Configure the AI voltage task timing according to the following table.
Table 8. NI 9775 Timing Configuration for DC Accuracy Verification
Sample Mode Samples per Channel Rate
Finite Sample 10,000 20 MS/s
c) Configure each test point according to the channel property settings in the following
table.
Table 9. NI 9775 Channel Properties Configuration for DC Accuracy Verification
AI.ADCTimingMode AI.Lowpass Enable
High Speed False
High Speed True
High Resolution True
d) Start the task.
e) Read the samples from the NI 9775.
f) Average the readings.
g) Stop and clear the task.
6. Compare the per-channel averages to the limits in the following table.
Table 10. NI 9775 Verification Limits for DC Accuracy
Channel Property Settings Test Point 1-Year Limits (V)
ADC Timing Mode Analog Lowpass
Filter
Location Value Upper Limit Lower Limit
High Speed Disabled Min -10.000 -9.931 -10.069
Mid 0.000 0.015 -0.015
Max 10.000 10.069 9.931
High Speed Enabled Min -10.000 -9.931 -10.069
Mid 0.000 0.015 -0.015
Max 10.000 10.069 9.931
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Table 10. NI 9775 Verification Limits for DC Accuracy (Continued)
Channel Property Settings Test Point 1-Year Limits (V)
ADC Timing Mode Analog Lowpass
Filter
Location Value Upper Limit Lower Limit
High Resolution Enabled Min -10.000 -9.931 -10.069
Mid 0.000 0.015 -0.015
Max 10.000 10.069 9.931
Note The test limits in this table are derived using the values in the NI 9775
Accuracy Under Calibration Conditions table.
Note The uncertainty of the calibration standard is not included in these
limits.
7. Set the calibrator to Standby mode (STBY).
8. Repeat steps 3 through 7 for each test point in the NI 9775 Verification Limits for DC
Accuracy table.
9. Repeat steps 3 through 8 for each channel configuration in the NI 9775Channel
Properties Configuration for DC Accuracy Verification table.
10. Disconnect the NI 9775 from the calibrator.
Adjustment
The following performance adjustment procedure describes the sequence of operation required
to adjust the NI 9775.
AC Accuracy Adjustment
Complete the following procedure to adjust the AC accuracy performance of the NI 9775.
Note Adjust AC accuracy first, then DC accuracy. Always adjust DC accuracy
whenever you adjust AC accuracy.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9775 to the calibrator as shown in the AC Accuracy Verification section.
3. Adjust the NI 9775.
a) Initialize a calibration session on the NI 9775. The default password is NI.
b) Input the external temperature in degrees Celsius with the DAQmx Set Temperature
C Series Function.
c) Call the NI 9775 get C Series adjustment points function with coupling mode set to
AC to obtain an array of recommended calibration frequency points for the NI 9775
Accuracy Adjustment.
d) Set the calibrator to a frequency value determined by the array or recommended
calibration frequency points. The AC voltage amplitude should be the value as
shown in the following table.
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Table 11. Calibrator Configuration for AC Accuracy Adjustment
Output Function Amplitude (V RMS)
AC Voltage 2.00
e) Wait for one second to allow the output amplitude of the calibrator to settle.
f) Call and configure the NI 9775 adjustment function according to the following table.
Table 12. NI 9775 AC Adjustment Configuration
Physical Channel Coupling Mode Reference Value
cDAQMod8/AI0:3 AC The output frequency setting of the calibrator in Hz
g) Repeat steps d through f for each point in the adjustment points array obtained in
step c.
h) Close and commit the calibration session.
i) Clear the task.
4. Set the calibrator to Standby mode (STBY).
5. Disconnect the NI 9775 from the calibrator.
DC Accuracy Adjustment
Complete the following procedure to adjust the DC accuracy performance of the NI 9775.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9775 to the calibrator as shown in the AC Accuracy Verification section.
3. Adjust the NI 9775.
a) Initialize a calibration session on the NI 9775. The default password is NI.
b) Input the external temperature in degrees Celsius.
c) Call the NI 9775 get C Series adjustment points function with coupling mode set to
DC to obtain an array of recommended calibration voltages for the NI 9775.
d) Set the calibrator to a reference value determined by the array of recommended
calibration voltages.
e) Set the calibrator to Operate mode (OPR).
f) Call and configure the NI 9775 adjustment function according to the following table.
Table 13. NI 9775 DC Adjustment Configuration
Physical Channel Coupling Mode Reference Value
cDAQMod8/AI0:3 DC The output voltage setting of the calibrator
g) Set the calibrator to Standby mode (STBY).
h) Repeat steps d through g for each calibration voltage in the array.
i) Close and commit the calibration session.
j) Clear the task.
4. Disconnect the NI 9775 from the calibrator.
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EEPROM Update
When an adjustment procedure is completed, the NI 9775 internal calibration memory
(EEPROM) is immediately updated.
If you do not want to perform an adjustment, you can update the calibration date and onboard
calibration temperature without making any adjustments by initializing an external calibration,
setting the C Series calibration temperature, and closing the external calibration.
Reverification
Repeat the Verification section to determine the As-Left status of the device.
Note You must remove and re-insert the module from the chassis before running
verification.
Note If any test fails Reverification after performing an adjustment, verify that you
have met the Test Conditions before returning your device to NI. Refer to
Worldwide Support and Services for assistance in returning the device to NI.
Accuracy Under Calibration Conditions
The values in the following table are based on calibrated scaling coefficients, which are stored
in the onboard EEPROM.
The following accuracy table is valid for calibration under the following conditions:
• Ambient temperature 23 °C ± 5 °C
• NI 9775 installed in slot 8 of an cDAQ-9178 chassis
• Slots 1 through 7 of the cDAQ-9178 chassis are empty
Note The test limits listed in NI 9775 Verification Limits for DC Accuracy table are
derived using the values in the following table.
Table 14. NI 9775 Accuracy Under Calibration Conditions
Accuracy Type Gain Error Offset Error (mV)
AC ±1.39% —
DC ±0.54% ±15 mV
Note For operational specifications, refer to the NI 9775 Datasheet online at
ni.com/manuals.
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Worldwide Support and Services
The NI website is your complete resource for technical support. At ni.com/support, you have
access to everything from troubleshooting and application development self-help resources to
email and phone assistance from NI Application Engineers.
Visit ni.com/services for NI Factory Installation Services, repairs, extended warranty, and
other services.
Visit ni.com/register to register your NI product. Product registration facilitates technical
support and ensures that you receive important information updates from NI.
A Declaration of Conformity (DoC) is our claim of compliance with the Council of the
European Communities using the manufacturer’s declaration of conformity. This system
affords the user protection for electromagnetic compatibility (EMC) and product safety. You
can obtain the DoC for your product by visiting ni.com/certification. If your product supports
calibration, you can obtain the calibration certificate for your product at ni.com/calibration.
NI corporate headquarters is located at 11500 North Mopac Expressway, Austin, Texas,
78759-3504. NI also has offices located around the world. For telephone support in the United
States, create your service request at ni.com/support or dial 1 866 ASK MYNI (275 6964). For
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support phone numbers, email addresses, and current events.
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376632A-01 February 28, 2018
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