National Instruments NI 9219 Manual

CALIBRATION PROCEDURE
NI 9219
4-Channel, 24-Bit, Universal Analog Input Module
This document contains information for calibrating the NI 9219. For more information on
calibration, visit ni.com/calibration.
Contents
Software.................................................................................................................................... 2
Documentation.......................................................................................................................... 2
Test Equipment......................................................................................................................... 2
Test Conditions......................................................................................................................... 4
Initial Setup............................................................................................................................... 5
Verification ............................................................................................................................... 5
Voltage Accuracy Verification......................................................................................... 5
Thermocouple Accuracy Verification .............................................................................. 8
Current Accuracy Verification ......................................................................................... 10
2-Wire Resistance Accuracy Verification ........................................................................ 11
Quarter-Bridge Accuracy Verification ............................................................................. 13
4-Wire Resistance Accuracy Verification ........................................................................ 15
4-Wire RTD Accuracy Verification ................................................................................. 17
3-Wire RTD Accuracy Verification ................................................................................. 19
Half-Bridge Accuracy Verification .................................................................................. 22
Full-Bridge Accuracy Verification ................................................................................... 27
Adjustment................................................................................................................................ 31
Voltage and Thermocouple Accuracy Adjustment .......................................................... 31
Current Accuracy Adjustment .......................................................................................... 32
4-Wire and 2-Wire Resistance Accuracy Adjustment...................................................... 33
4-Wire RTD, 3-Wire RTD, and Quarter-Bridge Accuracy Adjustment .......................... 34
Half-Bridge Accuracy Adjustment ................................................................................... 35
Full-Bridge Accuracy Adjustment.................................................................................... 37
EEPROM Update ..................................................................................................................... 38
Reverification ........................................................................................................................... 38
Accuracy Under Calibration Conditions .................................................................................. 38
NI Services ............................................................................................................................... 40

2|ni.com |NI 9219 Calibration Procedure
Software
Calibrating the NI 9219 requires the installation of NI-DAQmx 9.3 or 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.
Documentation
Consult the following documents for information about the NI 9219, NI-DAQmx, and your
application software. All documents are available on ni.com and help files install with the
software.
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.
NI cDAQ-9174/9178 USB Chassis Quick Start
NI-DAQmx installation and hardware setup
NI 9219 Operating Instructions and Specifications
NI 9219 specific information, specifications, and calibration interval
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 9219 Calibration Procedure |© National Instruments Corporation |3
Table 1. Recommended Equipment
Equipment
Recommended
Model Where Used Minimum Requirements
Source Fluke 5700A Voltage Accuracy,
Thermocouple
Accuracy
Use a device that can source voltages as
high as 48 V and meets the following
specifications:
Noise:
≤5 mVpkpk 0.1 Hz–10 Hz at 48 V
≤500 μVpkpk 0.1 Hz–10 Hz at 12 V
≤500 μVpkpk 0.1 Hz–10 Hz at 3.2 V
≤50 μVpkpk 0.1 Hz–10 Hz at 0.8 V
≤5μVpkpk 0.1 Hz–10 Hz at 0.1 V
Current Accuracy Use a current source with noise
≤500 nApkpk 0.1 Hz–10 Hz.
Half-Bridge
Accuracy,
Full-Bridge
Accuracy
Use a voltage source with noise
≤500 μVpkpk 0.1 Hz–10 Hz at 3 V.
DMM (x2) NI 4071 Voltage Accuracy,
Thermocouple
Accuracy
Use a DMM with ≤30 ppm uncertainty for
voltage, and ≤0.8 μV offset error in
smallest range.
Resistance
Accuracy, RTD
Accuracy,
Quarter-Bridge
Accuracy
Use a DMM with ≤60 ppm uncertainty for
resistance, and ≤0.01 Ωoffset error in
smallest range.
Half-Bridge
Accuracy,
Full-Bridge
Accuracy
(DMM1) Use one DMM with ≤15 ppm
uncertainty for voltages under 3 V.
(DMM2) Use a second DMM with ≤20
ppm for uncertainty voltages under 1 V
and ≤0.8 μV offset error in smallest range.
Current Accuracy ≤270 ppm uncertainty for current,
≤2 nA offset error in smallest range

4|ni.com |NI 9219 Calibration Procedure
Test Conditions
The following setup and environmental conditions are required to ensure the NI 9219 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 9219 measurement
circuitry is at a stable operating temperature.
Discrete
Resistors
—RTD Accuracy TCR: ≤10 ppm/°C
Resistor values: 4020 Ω± 1%, 402 Ω
± 1%, 20 Ω± 5%, 4.99 Ω±5%
Resistance
Accuracy
TCR: ≤10 ppm/°C
Resistor values: 8450 Ω± 1%, 845 Ω
± 1%, 20 Ω±5%
Quarter-Bridge
Accuracy
TCR: ≤10 ppm/°C
Resistor values: 309 Ω ± 1%, 121 Ω ±
1%, 4.99 Ω±5%
Half-Bridge
Accuracy
TCR: ≤10 ppm/°C
Resistor values: 1 kΩ± 1% (x2)
Full-Bridge
Accuracy
TCR: ≤10 ppm/°C
Resistor values: 10 kΩ± 1% (x2)
cDAQ
Chassis
NI cDAQ-9178 All —
Connection
Accessory
NI 9972 All —
Table 1. Recommended Equipment (Continued)
Equipment
Recommended
Model Where Used Minimum Requirements

NI 9219 Calibration Procedure |© National Instruments Corporation |5
Initial Setup
Complete the following steps to set up the NI 9219.
1. Install the NI-DAQmx driver software.
2. Install the NI 9219 in slot 8 of the NI cDAQ-9178 chassis. Leave slots 1 through 7 of the
NI cDAQ-9178 chassis empty.
3. Launch Measurement & Automation Explorer (MAX).
4. Right-click the device name and select Self-Test to ensure that the device is working
properly.
Verification
This section provides instructions for verifying the NI 9219 specifications. The following
performance verification procedures describe the sequence of operation and test points required
to verify the NI 9219 and assumes that adequate traceable uncertainties are available for the
calibration references.
Caution The analog inputs on the NI 9219 are not grounded (floating). Ensure that
a single point in the test system is connected to ground to prevent the entire system
from floating.
Voltage Accuracy Verification
Complete the following steps to verify the voltage accuracy of an NI 9219.
1. Connect the NI 9219 to the DMM and source as shown in Figure 1.

6|ni.com |NI 9219 Calibration Procedure
Figure 1. Voltage Accuracy Verification Connections to the NI 9219
2. Set the source to the appropriate test point value indicated in Table 4. Use the smallest
available range needed to source each test point. Using a range larger than necessary creates
unwanted additional noise.
3. Configure the DMM for a voltage measurement in the lowest appropriate range according
to the test point from Table 4.
4. Enable Auto Zero on the DMM.
5. Acquire a voltage reading with the DMM. Record this measurement as Vref.
6. Acquire and average samples.
a. Create an AI voltage task on the NI 9219 according to Table 2.
b. Configure the AI voltage task timing according to Table 3.
Table 2. NI 9219 Configuration for Voltage Accuracy Verification
Measurement Type Minimum (V) Maximum (V)
Vo l t a g e –60 60
–15 15
–4 4
–1 1
–0.125 0.125
V+
V–
HI
V
LO
NI 9219
DMM
Source
HI (4)
LO (5)
Ch 0
HI (4)
LO (5)
Ch 1
HI (4)
LO (5)
Ch 2
HI (4)
LO (5)
Ch 3

NI 9219 Calibration Procedure |© National Instruments Corporation |7
c. Start the task.
d. Acquire 20 voltage readings with the NI 9219 and average the readings.
e. Record the average of the readings as Vchannel.
f. Clear the task.
7. Perform the following calculation using the recorded Vref and Vchannel values.
8. Compare the calculation result to the Upper Limit and Lower Limit values in Table 4.
Table 3. NI 9219 Timing Configuration
ADC Timing Mode Sample Timing Type
High Resolution On Demand
Table 4. NI 9219 Verification Test Limits for Voltage Accuracy
Range Test Point 1–Year Limits
Minimum
(V)
Maximum
(V) Location
Value
(V)
Lower
Limit (V)
Upper
Limit (V)
–60 60 Max 48 –0.07990 0.07990
Mid 0.0 –0.00100 0.00100
Min –48 –0.07990 0.07990
–15 15 Max 12 –0.02030 0.02030
Mid 0.0 –0.00080 0.00080
Min –12 –0.02030 0.02030
–4 4 Max 3.2 –0.00580 0.00580
Mid 0.0 –0.00060 0.00060
Min –3.2 –0.00580 0.00580
–1 1 Max 0.80 –0.000450 0.000450
Mid 0.00 –0.000014 0.000014
Min –0.80 –0.000450 0.000450
–0.125 0.125 Max 0.10 –0.000063 0.000063
Mid 0.00 –0.000010 0.000010
Min –0.10 –0.000063 0.000063
Accuracy =Vchannel –Vref

8|ni.com |NI 9219 Calibration Procedure
Note The test limits listed in Tables 4 are derived using the values in Table 53.
9. Set the source output to zero.
10. Repeat steps 2 through 9 for all test points on the NI 9219.
11. Repeat steps 2 through 10 for all channels on the NI 9219.
12. Disconnect the source and the DMM from the device.
Thermocouple Accuracy Verification
Complete the following steps to verify the thermocouple accuracy of an NI 9219.
1. Connect the NI 9219 to the DMM and source as shown in Figure 2.
Figure 2. Thermocouple Accuracy Verification Connections to the NI 9219
2. Set the source to the appropriate test point value indicated in Table 7. Use the smallest
available range needed to source each test point. Using a range larger than necessary creates
unwanted additional noise.
3. Configure the DMM for a voltage measurement in the lowest appropriate range according
to the test point from Table 7.
4. Enable Auto Zero on the DMM.
5. Acquire a voltage reading with the DMM. Record the measurement as Vref.
6. Acquire and average samples.
a. Create an AI thermocouple task on the NI 9219 according to Table 5.
V+
V–
HI
V
LO
NI 9219
DMM
Source
HI (4)
LO (5)
Ch 0
HI (4)
LO (5)
Ch 1
HI (4)
LO (5)
Ch 2
HI (4)
LO (5)
Ch 3

NI 9219 Calibration Procedure |© National Instruments Corporation |9
b. Configure the AI thermocouple task timing according to Table 6.
c. Start the task.
d. Acquire 20 unscaled I32 readings with the NI 9219.
e. Record the average of the readings as dataunscaled.
f. Clear the task.
7. Scale the data by using the formula below to change the unscaled data into volts.
where rangemax is the maximum value (mV) in Table 7.
8. Perform the following calculation using the recorded Vref and Vchannel values.
9. Compare the calculation result to the Upper Limit and Lower Limit values in Table 7.
Note The test limits listed in Table 7 are derived using the values in Table 53.
10. Set the source output to zero.
11. Repeat steps 2 through 10 for all test points on the NI 9219.
12. Repeat steps 2 through 11 for all channels on the NI 9219.
13. Disconnect the source and the DMM from the device.
Table 5. NI 9219 Configuration for Thermocouple Accuracy Verification
Measurement Type Minimum (°C) Maximum (°C)
Thermocouple 0100
Table 6. NI 9219 Timing Configuration
ADC Timing Mode Sample Timing Type
High Resolution On Demand
Table 7. NI 9219 Verification Test Limits for Thermocouple Accuracy
Range Test Point 1–Year Limits
Minimum
(mV)
Maximum
(mV) Location Value (V)
Lower Limit
(V)
Upper Limit
(V)
–125 125 Max 0.10 –0.000041 0.000041
Min 0.00 –0.000010 0.000010
Vchannel
dataunscaled
223
-------------------------------rangemax
×=
Accuracy Vchannel Vref –=

10 |ni.com |NI 9219 Calibration Procedure
Current Accuracy Verification
Complete the following steps to verify the current accuracy of an NI 9219.
1. Connect the NI 9219 to the DMM and source as shown in Figure 3.
Figure 3. Current Accuracy Verification Connections to the NI 9219
2. Set the current source to the appropriate test point value indicated in Table 10. Use the
smallest available range needed to source each test point. Using a range larger than
necessary creates unwanted additional noise.
3. Configure the DMM for a current measurement in the lowest appropriate range according
to the test point from Table 10.
4. Enable Auto Zero on the DMM.
5. Acquire and average samples.
a. Create an AI current task on the NI 9219 according to Table 8.
b. Configure the AI current task timing according to Table 9.
Table 8. NI 9219 Configuration for Current Accuracy Verification
Measurement Type Physical Channels Minimum (A) Maximum (A)
Current ai0:3 –0.025 0.025
I+
I–
HI
AMPS
LO
NI 9219
DMM
Source
HI (3)
LO (5)
Ch 0
HI (3)
LO (5)
Ch 1
HI (3)
LO (5)
Ch 2
HI (3)
LO (5)
Ch 3