National Instruments 9218 Manual

CALIBRATION PROCEDURE
NI 9218
2-Channel, 24-Bit, Universal Analog Input Module
This document contains information for calibrating the National Instruments 9218. For more
information on calibration, visit ni.com/calibration.
Contents
Software.................................................................................................................................... 1
Documentation.......................................................................................................................... 2
Test Equipment......................................................................................................................... 3
Test Conditions......................................................................................................................... 4
Initial Setup............................................................................................................................... 5
Verification ............................................................................................................................... 5
Current Accuracy Verification, 20 mA mode .................................................................. 6
Voltage Accuracy Verification, 60 V mode ..................................................................... 7
Voltage Accuracy Verification, 16 V mode ..................................................................... 9
Voltage Accuracy Verification, 65 mV mode .................................................................. 10
Voltage Accuracy Verification, IEPE 5 V mode.............................................................. 12
Bridge Accuracy Verification, 22 mV/V mode................................................................ 14
Adjustment................................................................................................................................ 17
Voltage Accuracy Adjustment, 16 V mode...................................................................... 17
Voltage Accuracy Adjustment, 60 V mode...................................................................... 18
Voltage Accuracy Adjustment, 65 mV mode................................................................... 19
Current Accuracy Adjustment, 20 mA mode ................................................................... 20
Voltage Accuracy Adjustment, IEPE 5 V mode .............................................................. 20
Bridge Accuracy Adjustment, 22 mV/V mode ................................................................ 21
EEPROM Update ..................................................................................................................... 23
Reverification ........................................................................................................................... 23
Accuracy Under Calibration Conditions .................................................................................. 23
Worldwide Support and Services ............................................................................................. 24
Pinout Signals ........................................................................................................................... 25
Software
Calibrating the NI 9218 requires the installation of NI-DAQmx 15.1or later on the calibration
system. 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.

2|ni.com |NI 9218 Calibration Procedure
Documentation
Consult the following documents for information about the NI 9218, NI-DAQmx, and your
application software. All documents are available on ni.com and help files install with the
software.
NI cDAQ-9174/9178 USB Chassis Quick Start
NI-DAQmx installation and hardware setup
NI 9218 Getting Started Guide
NI 9218 connection information
NI 9218 Datasheet
NI 9218 circuitry and specifications
NI-DAQmx Readme
Operating system and application software support in NI-DAQmx
LabVIEW Help
LabVIEW programming concepts and reference information about NI-DAQmx
VIs and functions
NI-DAQmx C Reference Help
Reference information for NI-DAQmx C functions and NI-DAQmx C properties
NI-DAQmx .NET Help Support for Visual Studio
Reference information for NI-DAQmx .NET methods and NI-DAQmx .NET
properties, key concepts, and a C enum to .NET enum mapping table

NI 9218 Calibration Procedure |© National Instruments |3
Test Equipment
Table 1 lists the equipment recommended for the performance verification and adjustment
procedures. If the recommended equipment is not available, select a substitute using the
requirements listed in Table 1.
Table 1. Recommended Equipment
Equipment
Recommended
Model
Where Used
Minimum RequirementsVerification Adjustment
Calibrator Fluke 5700A
±60 V,
±16 V,
±65 mV
mode
±16 V,
±65 mV
mode
Use a device that can source
voltages as high as ±50 V and
meets the following
specifications:
≤100 ppm gain error.
≤3 µV offset error.
<3 µV offset at voltages less
than 60 mV.
<200 mV offset at voltages
less than 15 V.
<1 mV offset at voltages less
than 60 V.
± 20 mA
mode —
Use a device that can source
currents as high as ±15 mA,
<200 ppm gain error, and
offset error <1 µA.
IEPE ±5 V
mode
IEPE ±5 V
mode
Use a device that can source
1 kHz, 3 Vrms AC sinusoidal
signals with amplitude
uncertainty of 200 ppm
or less.
DMM (x2) NI 4071 —±60 V mode Use a DMM with <40 Ωof
error at resistances <400 kΩ.
Bridge,
±22 mV/V
mode
Bridge,
±22 mV/V
mode
For DMM1, use one DMM
with <50 ppm gain error, and
<50 µV of offset error at
voltages <3.5 V.
For DMM2, use a second
DMM with <50 ppm gain
error, and <2 µV of offset
error at voltages <50 mV.

4|ni.com |NI 9218 Calibration Procedure
Test Conditions
The following setup and environmental conditions are required to ensure the NI 9218 meets
published specifications.
• Keep connections to the device 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 device are secure.
• Use shielded copper wire for all cable connections to the device. Use twisted-pairs wire to
eliminate noise and thermal offsets.
• Maintain an ambient temperature of 23 ±5 °C. The device temperature will be greater than
the ambient temperature.
• Keep relative humidity below 80%.
• Allow a warm-up time of at least 10 minutes to ensure that the NI 9218 measurement
circuitry is at a stable operating temperature.
• Only one of each NI 9982, NI 9983, and NI 9987 is sufficient for this calibration procedure.
Discrete
Resistors —
Bridge,
±22 mV
mode
Bridge,
±22 mV
mode
TCR: <25 ppm/°C
Resistor values:
10 kΩ(2x), 249 Ω
cDAQ
Chassis
NI cDAQ-9178 All All —
Measurement
Adapter
NI 9982 (x2) ±16 V,
±65 mV,
Bridge
±22 mV/V,
IEPE ±5 V
mode
±60 V, ±16 V,
±65 mV,
Bridge
±22 mV/V,
IEPE ±5 V
mode
—
NI 9983 (x2) ±20 mA
mode
— —
NI 9987 (x2) ±60 V mode — —
Table 1. Recommended Equipment (Continued)
Equipment
Recommended
Model
Where Used
Minimum RequirementsVerification Adjustment

NI 9218 Calibration Procedure |© National Instruments |5
Initial Setup
Complete the following steps to set up the NI 9218.
1. Install NI-DAQmx.
2. Make sure the NI cDAQ-9178 power source is not connected.
3. Connect the NI cDAQ-9178 to the system safety ground.
a. Attach a ring lug to a 14 AWG (1.6 mm) wire.
b. Connect the ring lug to the ground terminal on the side of the NI cDAQ-9178 using
the ground screw.
c. Attach the other end of the wire to the system safety ground.
4. Install the module in slot 8 of the NI cDAQ-9178 chassis. Leave slots 1 through 7 of the
NI cDAQ-9178 chassis empty.
5. Connect the NI cDAQ-9178 chassis to your host computer.
6. Connect the power source to the NI cDAQ-9178 chassis.
7. Launch Measurement & Automation Explorer (MAX).
8. Right-click the device name and select Self-Test to ensure that the module is working
properly.
9. Ensure that the ambient temperature of your test environment is 23 °C ±5 °C.
Verification
This section provides instructions for verifying the NI 9218 specifications. The following
performance verification procedures describe the sequence of operations and test points required
to verify the NI 9218 and assumes that adequate traceable uncertainties are available for the
calibration references.
Note Each verification procedure requires the software configuration of a
measurement adapter. The software configuration is done through Measurement &
Automation Explorer. See KB 6T8GKTUX for how to configure your measurement
adapter in MAX.
Caution Each verification may have different wiring schemes. Consult the
diagram on your measurement adapter or Figure 10 and 11 for the most appropriate
connection diagram.
Caution The analog inputs on the NI 9218 are not grounded (floating). Ensure that
a single point in the test system is connected to ground to prevent the entire system
from floating.

6|ni.com |NI 9218 Calibration Procedure
Current Accuracy Verification, 20 mA mode
Complete the following procedure to determine the As-Found status of the NI 9218.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9218 to the calibrator as shown in Figure 1.
Figure 1. Current Accuracy Verification Connections
3. Set the calibrator current to a Test Point value indicated in Table 4.
4. Set the calibrator to Operate mode (OPR).
5. Configure the NI 9218 for the NI 9983 measurement adapters using MAX.
6. Acquire and average samples.
a. Create an AI current task on the NI 9218 according to Table 2.
b. Configure the AI current task timing according to Table 3.
c. Start the task.
d. Average the readings and record the average.
e. Stop and clear the task.
7. Set the calibrator to Standby mode (STBY).
Table 2. NI 9218 Configuration for Accuracy Verification
Min (mA) Max (mA) Scaled Units Channel Configuration
-20 20 Amps DC Coupled
Table 3. NI 9218 Timing Configuration
Sample Mode Samples Per Channel Rate (kHz)
Finite Samples 512 k 51.2
EX+
EX–
AI+
AI–
Calibrator
–
+
NI 9983
EX+
EX–
AI+
AI–
NI 9983 NI 9218
DSUB /LEMO
DSUB/LEMO
CH 0
CH 1

NI 9218 Calibration Procedure |© National Instruments |7
8. Compare the average to the limits in Table 4.
9. Repeat steps 3 through 8 for each test point in Table 4.
Note The test limits listed in Table 4 are derived using the values in Table 32.
Note The uncertainty of the calibration standard is not included in these limits.
10. Disconnect the calibrator from the NI 9218.
Voltage Accuracy Verification, 60 V mode
Complete the following procedure to determine the As-Found status of the NI 9218.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9218 to the calibrator as shown in Figure 2.
Figure 2. Voltage Accuracy Verification Connections
3. Set the calibrator voltage to a Test Point value indicated in Table 7.
4. Set the calibrator to Operate mode (OPR).
5. Configure the NI 9218 for the 9987 measurement adapters using MAX.
Table 4. NI 9218 Verification Test Limits for Accuracy
Test Point 2-Year Limits
Location Value (mA) Lower Limit (mA) Upper Limit (mA)
Max 15 14.929 15.071
Mid 0-0.008 0.008
Min -15 -15.071 -14.929
AI+
AI–
NI 9987
Calibrator
–
+
AI+
AI–
NI 9987 NI 9218
DSUB/LEMO
CH 0
DSUB/LEMO
CH 1

8|ni.com |NI 9218 Calibration Procedure
6. Acquire and average samples.
a. Create an AI voltage task on the NI 9218 according to Table 5.
b. Configure the AI voltage task timing according to Table 6.
c. Start the task.
d. Average the readings and record the average.
e. Stop and clear the task.
7. Set the calibrator to Standby mode (STBY).
8. Compare the average to the limits in Table 7.
9. Repeat steps 3 through 8 for each test point in Table 7.
Note The test limits listed in Table 7 are derived using the values in Table 32.
Note The uncertainty of the calibration standard is not included in these limits.
10. Disconnect the calibrator from the device.
Table 5. NI 9218 Configuration for Accuracy Verification
Min (V) Max (V) Scaled Units Channel Configuration
-60 60 Vo l t s DC Coupled
Table 6. NI 9218 Timing Configuration
Sample Mode Samples Per Channel Rate (kHz)
Finite Samples 512 k 51.2
Table 7. NI 9218 Verification Test Limits for Accuracy
Test Point 2-Year Limits
Location Value (V) Lower Limit (V) Upper Limit (V)
Max 50 49.827 50.173
Mid 0-0.008 0.008
Min -50 -50.173 -49.827

NI 9218 Calibration Procedure |© National Instruments |9
Voltage Accuracy Verification, 16 V mode
Complete the following procedure to determine the As-Found status of the NI 9218.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9218 to the calibrator as shown in Figure 3.
Figure 3. Voltage Accuracy Verification Connections
3. Set the calibrator voltage to a Test Point value indicated in Table 10.
4. Set the calibrator to Operate mode (OPR).
5. Configure the NI 9218 for the 9982 measurement adapters using MAX.
6. Acquire and average samples.
a. Create an AI voltage task on the NI 9218 according to Table 8.
b. Configure the AI voltage task timing according to Table 9.
c. Start the task.
d. Average the readings and record the averages.
e. Stop and clear the task.
7. Set the calibrator to Standby mode (STBY).
Table 8. NI 9218 Configuration for Accuracy Verification
Min (V) Max (V) Scaled Units Channel Configuration
-16 16 Volts DC Coupled
Table 9. NI 9218 Timing Configuration
Sample Mode Samples Per Channel Rate (kHz)
Finite Samples 512 k 51.2
AI+
AI–/EX–
NI 9982
Calibrator
–
+
AI+
AI–/EX–
NI 9982NI 9218
DSUB/LEMO
CH 0
DSUB/LEMO
CH 1

10 |ni.com |NI 9218 Calibration Procedure
8. Compare the averages to the limits in Table 10.
9. Repeat steps 3 through 8 for each test point in Table 10.
Note The test limits listed in Table 10 are derived using the values in Table 32.
Note The uncertainty of the calibration standard is not included in these limits.
10. Disconnect the calibrator from the device.
Voltage Accuracy Verification, 65 mV mode
Complete the following procedure to determine the As-Found status of the NI 9218.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9218 to the calibrator as shown in Figure 4.
Figure 4. Voltage Accuracy Verification Connections
3. Set the calibrator voltage to a Test Point value indicated in Table 13.
4. Set the calibrator to Operate mode (OPR).
5. Configure the NI 9218 for the NI 9982 measurement adapters using MAX.
Table 10. NI 9218 Verification Test Limits for Accuracy
Test Point 2-Year Limits
Location Value (V) Lower Limit (V) Upper Limit (V)
Max 12 11.987 12.013
Mid 0-0.002 0.002
Min -12 -12.013 -11.987
NI 9982
EX+
EX–
AI+
AI–
Calibrator
–
+
NI 9982
AI+
AI–
NI 9218
DSUB/LEMO
CH 0
DSUB/LEMO
CH 1
EX+
EX–

NI 9218 Calibration Procedure |© National Instruments |11
6. Acquire and average samples.
a. Create an AI voltage task on the NI 9218 according to Table 11.
b. Configure the AI voltage task timing according to Table 12.
c. Start the task.
d. Average the readings and record the averages.
e. Stop and clear the task.
7. Set the calibrator to Standby mode (STBY).
8. Compare the averages to the limits in Table 13.
9. Repeat steps 3 through 8 for each test point in Table 13.
Note The test limits listed in Table 13 are derived using the values in Table 32.
Note The uncertainty of the calibration standard is not included in these limits.
10. Disconnect the calibrator from the device.
Table 11. NI 9218 Configuration for Accuracy Verification
Min (mV) Max (mV) Scaled Units Channel Configuration
-65 65 Vo l t s DC Coupled
Table 12. NI 9218 Timing Configuration
Sample Mode Samples Per Channel Rate (kHz)
Finite Samples 512 k 51.2
Table 13. NI 9218 Verification Test Limits for Accuracy
Test Point 2-Year Limits
Location Value (mV) Lower Limit (mV) Upper Limit (mV)
Max 50 49.906 50.094
Mid 0-0.024 0.024
Min -50 -50.094 -49.906

12 |ni.com |NI 9218 Calibration Procedure
Voltage Accuracy Verification, IEPE 5 V mode
Complete the following procedure to determine the As-Found status of the NI 9218.
1. Connect the NI 9218 to the calibrator as shown in Figure 5.
Figure 5. Voltage Accuracy Verification Connections
2. Configure calibrator according to Table 14.
Note The test limits listed in Table 14 are derived using the values in Table 32.
Note The uncertainty of the calibration standard is not included in these limits.
3. Configure the NI 9218 for the NI 9982 measurement adapters using MAX.
4. Acquire and calculate the AC magnitude.
a. Create an AI voltage task on the NI 9218 according to Table 15.
Table 14. NI 9218 Verification Test Limits for Accuracy
Test Point 2-Year Limits
Signal Type
Frequency
(kHz)
Amplitude
(Vrms)
Lower Limit
(Vrms)
Upper Limit
(Vrms)
Sine wave 1 1 0.998 1.002
32.994 3.006
Table 15. NI 9218 Configuration for Phase Matching Verification
Min (V) Max (V) Scaled Units Channel Configuration
-5 5Vo l t s AC Coupled
AI+
AI–
NI 9982
Calibrator
–
+
AI+
AI–
NI 9982 NI 9218
DSUB/LEMO
CH 0
DSUB/LEMO
CH 1

NI 9218 Calibration Procedure |© National Instruments |13
5. Use the DAQmx Channel Property node to configure the following properties:
a. AI.Coupling: AC
b. AI.Excit.Src: Internal
c. AI.Excit.VoltageorCurrent: Current
d. AI.Excit.Val: 0.002
6. Configure the AI voltage task timing according to Table 16.
a. Set the calibrator to Operate mode (OPR).
b. Commit the task using DAQmx Control Task Function/VI.
Note Wait 6 seconds for the AC coupling filter on the NI 9218 to settle before
acquiring samples.
c. Start the task.
d. Calculate and record the AC magnitude for each channel on the NI 9218.
NI recommends using the Extract Single Tone Information VI to calculate the
magnitude.
Note The output of the Extract Single Tone Information is in Vpk. To convert to
RMS, use the following equation:
Vrms = (Vpk) ÷ (√2)
e. Disable the calibrator.
f. Stop and clear the task.
7. Compare the AC magnitude to the limits in Table 14.
8. Repeat steps 2 through 7 for each test point in Table 14.
9. Disable the output of the calibrator and disconnect it from the NI 9218.
Table 16. NI 9218 Timing Configuration
Sample Mode Samples Per Channel Rate (kHz)
Finite Samples 512 k 51.2

14 |ni.com |NI 9218 Calibration Procedure
Bridge Accuracy Verification, 22 mV/V mode
Complete the following steps to verify the full-bridge accuracy of an NI 9218.
1. Connect a resistor network to the NI 9218 and two DMMs as shown in Figures 6, 7, or 8
for the appropriate test point value indicated in Table 17. Observe the following conditions
when connecting the equipment to the NI 9218.
• Connect the leads of DMM2 as close as possible to the AI+ and AI- terminals on the
NI 9982.
• Connect the leads of DMM1 as close as possible to the RS+ and RS- leads of the
NI 9982.
Figure 6. Bridge Accuracy Verification Connections (Configuration 1)
Figure 7. Bridge Accuracy Verification Connections (Configuration 2)
10 k˖
249 ˖
10 k˖
V
a
V
b
DMM 1
RS+
RS–
EX+
EX–
AI+
NI 9982
AI–
HI
LO
DMM 2
HI
LO
NI 9218
DSUB/LEMO
CH x
10 k˖
249 ˖
10 k˖
V
a
V
b
DMM 1
RS+
RS–
EX+
EX–
AI+
NI 9982
AI–
HI
LO
DMM 2
HI
LO
NI 9218
DSUB/LEMO
CH x

NI 9218 Calibration Procedure |© National Instruments |15
Figure 8. Bridge Accuracy Verification Connections (Configuration 3)
Note The test limits listed in Table 17 are derived using the values in Table 32.
Note The uncertainty of the calibration standard is not included in these limits.
2. Configure DMM1 for a voltage measurement in the 10 V range.
3. Enable autozero on DMM1.
4. Configure DMM2 for a voltage measurement in the 100 mV range.
5. Enable autozero on DMM2.
6. Configure the NI 9218 for the NI 9982 measurement adapters using MAX.
Table 17. NI 9218 Verification Test Limits for Accuracy
Excitation
Value
Test Point 2-Year Limits
Location Value
Lower Limit
(mV/V)
Upper Limit
(mV/V)
2 V Max Configuration 1 -0.050 0.050
Mid Configuration 2 -0.036 0.036
Min Configuration 3 -0.050 0.050
3.3 V Max Configuration 1 -0.022 0.022
Mid Configuration 2 -0.007 0.007
Min Configuration 3 -0.022 0.022
10 k˖
249 ˖
10 k˖
Va
Vb
DMM 1
RS+
RS–
EX+
EX–
AI+
NI 9982
AI–
HI
LO
DMM 2
HI
LO
NI 9218
DSUB/LEMO
CH x

16 |ni.com |NI 9218 Calibration Procedure
7. Acquire and average samples.
a. Create an AI bridge with excitation task on the NI 9218 according to Table 18.
b. Configure the AI Bridge with excitation task timing according to Table 19.
c. Start the task.
d. Record the DMM1 measurements as VDMM1.
e. Record the DMM2 measurement as VDMM2.
Note Perform the DMM measurements and the NI 9218 measurements as
simultaneously as possible in order to reduce error from drift in the resistors.
f. Average the NI 9218 readings and record the average as Ratiochannel.
g. Perform the following calculation using the two DMM measurements.
h. Perform the following calculation using the recorded Ratioref and Ratiochannel values.
Accuracy = Ratiochannel - Ratioref
i. Compare the result of step h to the limits in Table 17.
j. Stop and clear the task.
8. Repeat steps 2 through 7 for each test point in Table 17.
9. Repeat steps 1 through 8 for each excitation value specified in Table 17.
10. Disconnect the DMMs and resistors from the NI 9218.
11. Repeat steps 1 through 10 for each channel on the NI 9218.
Table 18. NI 9218 Configuration for Accuracy Verification
Min
(V/V)
Max
(V/V)
Channel
Configuration
Excitation
Value (V)
Excitation
Source
Bridge
Configuration
-0.022 0.022 DC Coupled 2Internal Full-Bridge
3.3
Table 19. NI 9218 Timing Configuration
Sample Mode Samples Per Channel Rate (kHz)
Finite Samples 512 k 51.2
Ratioref
VDMM2
VDMM1
------------------=

NI 9218 Calibration Procedure |© National Instruments |17
Adjustment
The following performance adjustment procedures describe the sequence of operation required
to adjust the NI 9218.
Voltage Accuracy Adjustment, 16 V mode
Complete the following procedure to adjust the accuracy performance of the NI 9218.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9218 to the calibrator as shown in Figure 3.
3. Configure the NI 9218 for the 9982 measurement adapters using MAX.
4. Adjust the NI 9218.
a. Initialize a calibration session on the NI 9218. The default password is NI.
b. Input the external temperature in degrees Celsius using the DAQmx Set Temperature
C Series Calibration function.
c. Call and configure the DAQmx Setup 9218 Calibration function according to
Table 20.
d. Call the DAQmx Get 9218 Calibration Adjustment Points function to obtain an array
of recommended calibration voltages for the NI 9218.
e. Set the calibrator to a reference value determined by the array of recommended
calibration voltages.
f. Set the calibrator to Operate mode (OPR).
g. Call and configure the DAQmx Adjust 9218 Calibration function according to
Table 21.
Note The NI 9218 acquisition starts each time the adjustment function is called.
h. Set the calibrator to Standby mode (STBY).
i. Repeat steps e through h for each point in the array of recommended calibration
voltages.
Table 20. Setup Configuration for 16 V Accuracy Adjustment
Min (V) Max (V) Physical Channels Measurement Type
-16 16 cDAQMod8/AIxVo l t a g e
Table 21. Adjustment Configuration
Physical Channel Reference Value
cDAQMod8/AIxThe recommended calibration voltage

18 |ni.com |NI 9218 Calibration Procedure
j. Use the DAQmx Close External Calibration to close and commit the calibration
session.
k. Repeat steps c through j for each channel.
5. Disconnect the NI 9218 from the calibrator.
Voltage Accuracy Adjustment, 60 V mode
Complete the following procedure to adjust the accuracy performance of the NI 9218.
1. You must complete the Voltage Accuracy Adjustment, 16 V mode section before starting
this section.
2. Connect the NI 9218 to the DMM as shown in Figure 9.
3. Configure the NI 9218 for the NI 9982 measurement adapters using MAX.
Figure 9. Voltage Accuracy Adjustment Connections
4. Adjust the NI 9218.
a. Initialize a calibration session on the NI 9218. The default password is NI.
b. Input the external temperature in degrees Celsius using the DAQmx Set Temperature
C Series Calibration function.
c. Call and configure the DAQmx Setup 9218 Calibration function according to
Table 22.
d. Set the DMM to the most appropriate range for 390 kΩresistance measurement.
e. Measure the resistance.
f. Call and configure the DAQmx Adjust 9218 Calibration function according to
Table 23.
Table 22. Setup Configuration for 60 V Accuracy Adjustment
Min (V) Max (V) Physical Channels Measurement Type
-60 60 cDAQMod8/AIxVoltage
Table 23. Adjustment Configuration
Physical Channel Reference Value
cDAQMod8/AIxThe reading from the DMM
AI+
AI–
NI 9982 NI 9218
DSUB/LEMO
DMM
LO
HI
CH x

NI 9218 Calibration Procedure |© National Instruments |19
g. Use the DAQmx Close External Calibration to close and commit the calibration
session.
h. Repeat steps c through g for each channel.
5. Disconnect the DMM from the NI 9218.
Voltage Accuracy Adjustment, 65 mV mode
Complete the following procedure to adjust the accuracy performance of the NI 9218.
1. Set the calibrator to Standby mode (STBY).
2. Connect the NI 9218 to the calibrator as shown in Figure 4.
3. Configure the NI 9218 for the NI 9982 measurement adapters using MAX.
4. Adjust the NI 9218.
a. Initialize a calibration session on the NI 9218. The default password is NI.
b. Input the external temperature in degrees Celsius using the DAQmx Set Temperature
C Series Calibration function.
c. Call and configure the DAQmx Setup 9218 Calibration function according to
Table 24.
d. Call the DAQmx Get 9218 Calibration Adjustment Points function to obtain an array
of recommended calibration voltages for the NI 9218.
e. Set the calibrator to a reference value determined by the array of recommended
calibration voltages.
f. Set the calibrator to Operate mode (OPR).
g. Call and configure the DAQmx Adjust 9218 Calibration function according to
Table 25.
Note The NI 9218 acquisition starts each time the adjustment function is called.
h. Set the calibrator to Standby mode (STBY).
i. Repeat steps e through h for each point in the array of recommended calibration
voltages.
Table 24. Setup Configuration for 65 mV Accuracy Adjustment
Min (V) Max (V) Physical Channels Measurement Type
-0.065 0.065 cDAQMod8/AIxVo l t a g e
Table 25. Adjustment Configuration
Physical Channel Reference Value
cDAQMod8/AIxThe recommended calibration voltage