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–