National Instruments NI 9219 Manual

NI-9219

CALIBRATION PROCEDURE
NI 9219
This document contains information for calibrating the National Instruments 9219. For more
information on calibration, visit ni.com/calibration.
Contents
Software Requirements........................................................................................................................ 1
Documentation Requirements.............................................................................................................. 2
Calibration Interval .............................................................................................................................. 2
Test Equipment .................................................................................................................................... 2
Test Conditions .................................................................................................................................... 4
Calibration Procedures......................................................................................................................... 4
Initial Setup.................................................................................................................................. 4
Verification .................................................................................................................................. 5
Voltage Accuracy Verification ............................................................................................ 6
Thermocouple Accuracy Verification ................................................................................. 8
Current Accuracy Verification............................................................................................. 10
2-Wire Resistance Accuracy Verification ........................................................................... 11
Quarter-Bridge Accuracy Verification ................................................................................ 12
4-Wire Resistance Accuracy Verification ........................................................................... 14
4-Wire RTD Accuracy Verification .................................................................................... 15
3-Wire RTD Accuracy Verification .................................................................................... 17
Half-Bridge Accuracy Verification ..................................................................................... 19
Full-Bridge Accuracy Verification ...................................................................................... 23
Adjustment................................................................................................................................... 25
Voltage and Thermocouple Accuracy Adjustment.............................................................. 26
Current Accuracy Adjustment ............................................................................................. 29
4-Wire and 2-Wire Resistance Accuracy Adjustment......................................................... 32
4-Wire RTD, 3-Wire RTD, and Quarter-Bridge Accuracy Adjustment.............................. 37
Half-Bridge Accuracy Adjustment ...................................................................................... 42
Full-Bridge Accuracy Adjustment....................................................................................... 45
Accuracy Under Calibration Conditions.............................................................................................. 48
Where to Go for Support ..................................................................................................................... 49
Software Requirements
Calibrating the NI 9219 requires installing NI-DAQmx 9.3 or later on the calibration system. You can
download NI-DAQmx from ni.com/downloads. NI-DAQmx supports a number of programming
languages, including LabVIEW, LabWindows/CVI, C/C++, C#, and Visual Basic .NET. When you
install NI-DAQmx you only need to install support for the ADE that you intend to use.
ni.com/manuals
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NI 9219 Calibration Procedure 2 ni.com
Documentation Requirements
For information about NI-DAQmx and the NI 9219, you can consult the following documents:
•NI 9219 Operating Instructions and Specifications—This document includes detailed information
about the NI 9219 and provides the published specification values for the NI 9219. Visit ni.com/
info and enter cseriesdoc for the most recent NI 9219 Operating Instructions and
Specifications.
The following documents are installed with NI-DAQmx. You also can find the latest versions of the
documentation at ni.com/manuals.
•DAQ Getting Started guides—These guides provide instructions for installing and configuring
NI-DAQ devices.
•NI DAQmx Help—This help file contains general information about measurement concepts, key
NI-DAQmx concepts, and common applications that apply to all programming environments.
•NI-DAQmx C Reference Help—This help file contains C reference and general information about
measurement concepts.
Calibration Interval
National Instruments recommends a calibration interval of one year for the NI 9219. You should adjust
the recommended calibration interval based on the measurement accuracy demands of your application.
Test Equipment
National Instruments recommends that you use the equipment in Table 1 for calibrating the NI 9219.
Table 1. Recommended Equipment
Equipment
Recommended
Model Parameter Measured Minimum Requirements
Source Fluke 5700A Voltage Accuracy,
Thermocouple Accuracy
If this instrument is unavailable, 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 Vpkpk 0.1 Hz–10 Hz at 12 V
500 Vpkpk 0.1 Hz–10 Hz at 3.2 V
50 Vpkpk 0.1 Hz–10 Hz at 0.8 V
5Vpkpk 0.1 Hz–10 Hz at 0.1 V
Current Accuracy If this instrument is unavailable, use a current
source with noise 500 nApkpk 0.1 Hz–10 Hz.
Half-Bridge Accuracy,
Full-Bridge Accuracy
If this instrument is unavailable, use a voltage
source with noise 500 Vpkpk 0.1 Hz–10 Hz
at 3 V.

©National Instruments Corporation 3 NI 9219 Calibration Procedure
DMM (x2) NI 4071 Voltage Accuracy,
Thermocouple Accuracy
If this instrument is unavailable, use a DMM
with 30 ppm uncertainty for voltage, and
0.8 V offset error in smallest range.
Resistance Accuracy,
RTD Accuracy,
Quarter-Bridge
Accuracy
If this instrument is unavailable, use a DMM
with 60 ppm uncertainty for resistance, and
0.01 offset error in smallest range.
Half-Bridge Accuracy,
Full-Bridge Accuracy
(DMM1) If this instrument is unavailable, use
one DMM with 15 ppm uncertainty for
voltages under 3 V.
(DMM2) If this instrument is unavailable, use
a second DMM with20 ppm for uncertainty
voltages under 1 V and 0.8 V offset error
in smallest range.
Current Accuracy 270 ppm uncertainty for current,
2 nA offset error in smallest range
Discrete
Resistors
—RTD Accuracy TCR: 10 ppm/°C
Resistor values: 4020 ± 1%, 402 ± 1%,
20 ± 5%, 4.99 ±5%
Resistance Accuracy TCR: 10 ppm/°C
Resistor values: 8450 ± 1%, 845 ± 1%,
20 ±5%
Quarter-Bridge
Accuracy
TCR: 10 ppm/°C
Resistor values: 309 ± 1%, 121 ± 1%,
4.99 ±5%
Half-Bridge Accuracy TCR: 10 ppm/°C
Resistor values: 1 k± 1% (x2)
Full-Bridge Accuracy TCR: 10 ppm/°C
Resistor values: 10 k± 1% (x2)
cDAQ
Chassis
NI cDAQ-9178 All —
Connection
Accessory
NI 9972 All —
Table 1. Recommended Equipment (Continued)
Equipment
Recommended
Model Parameter Measured Minimum Requirements

NI 9219 Calibration Procedure 4 ni.com
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 antennae, 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.
Calibration Procedures
The calibration process includes the following steps:
1. Initial Setup—Install the device and configure it in Measurement & Automation Explorer (MAX).
2. Verification—Verify the existing operation of the device. This step confirms whether the device is
operating within the published specifications prior to adjustment.
3. Adjustment—Adjust the calibration constants of the device. The adjustment procedure
automatically updates the calibration date and temperature in the EEPROM.
4. Reverification—Repeat the verification procedure to ensure that the device is operating within the
published specifications after adjustment.
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.

©National Instruments Corporation 5 NI 9219 Calibration Procedure
Verification
This section provides instructions for verifying the NI 9219 specifications. Refer to Figure 1, Table 2,
and Table 3 for the channel assignments, signal names, and terminal assignments of the NI 9219.
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.
Note The test limits listed in Tables 5, 7, 9, 11, 13, 15, 17, 19, 21, are derived using the values in
Table 24.
Figure 1. NI 9219 Channel and Terminal Assignments
Table 2. NI 9219 Signal Name
Terminal Signal Name Signal Description
1T+ TEDS Data
2T– TEDS COM
3EX+/HI*Positive excitation or input signal
4HI Positive input signal
5EX–/LO*Negative excitation or input signal
6LO Negative input signal
* Depending on the mode, terminals 3 and 5 are either the excitation signals or the input signals.
1
2
3
4
5
6
1
2
3
4
5
6
1
2
3
4
5
6
1
2
3
4
5
6
Ch 0
Ch 1
Ch 2
Ch 3

NI 9219 Calibration Procedure 6 ni.com
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 2.
Figure 2. Voltage Accuracy Verification Connections to the NI 9219
Table 3. NI 9219 Terminal Assignments by Mode
Mode
Terminal
123456
Vo l t a g e T+ T– —HI LO —
Current T+ T– HI —LO —
4-Wire Resistance T+ T– EX+ HI EX– LO
2-Wire Resistance T+ T– HI —LO —
Thermocouple T+ T– —HI LO —
4-Wire RTD T+ T– EX+ HI EX– LO
3-Wire RTD T+ T– EX+ —EX– LO
Quarter-Bridge T+ T– HI —LO —
Half-Bridge T+ T– EX+ HI EX– —
Full-Bridge T+ T– EX+ HI EX– LO
Digital In T+ T– —HI LO —
Open Contact T+ T– HI —LO —
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

©National Instruments Corporation 7 NI 9219 Calibration Procedure
2. Set the source to the appropriate test point value indicated in Table 5. 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 5.
4. Enable Auto Zero on the DMM.
5. Acquire a voltage reading with the DMM. Record this measurement as Vref.
6. Create an AI voltage channel on the NI 9219. Configure the channel according to Table 4.
7. Acquire 20 voltage readings with the NI 9219. Record the average of the readings as Vchannel.
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 5.
Table 4. NI 9219 Configuration for Voltage Accuracy Verification
Measurement
Type Min (V) Max (V)
ADC Timing
Mode
Sample Timing
Type
Voltage –60 60 High Resolution On Demand
–15 15
–4 4
–1 1
–0.125 0.125
Table 5. NI 9219 Verification Test Limits for Voltage Accuracy
Range Test Poi nt 1–Ye a r L i m i t s
Minimum
(V)
Maximum
(V) Location Va l ue (V)
Lower Limit
(V)
Upper Limit
(V)
–60 60 Max 48 –0.03670 0.03670
Mid 0.0 –0.00100 0.00100
Min –48 –0.03670 0.03670
–15 15 Max 12 –0.00980 0.00980
Mid 0.0 –0.00080 0.00080
Min –12 –0.00980 0.00980
–4 4Max 3.2 –0.00300 0.00300
Mid 0.0 –0.00060 0.00060
Min –3.2 –0.00300 0.00300
Accuracy Vchannel Vref –=

NI 9219 Calibration Procedure 8 ni.com
10. Set the source output to zero and clear the acquisition.
11. Repeat steps 2 through 10 for all test points and all channels on the NI 9219. NI recommends that
you verify the values for all the iterations listed in Table 5 for each channel, but you can save time
by verifying only the ranges, values, and channels used in your application.
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 3.
Figure 3. Thermocouple Accuracy Verification Connections to the NI 9219
–1 1Max 0.80 –0.000260 0.000260
Mid 0.00 –0.000014 0.000014
Min –0.80 –0.000260 0.000260
–0.125 0.125 Max 0.10 –0.000041 0.000041
Mid 0.00 –0.000010 0.000010
Min –0.10 –0.000041 0.000041
Table 5. NI 9219 Verification Test Limits for Voltage Accuracy (Continued)
Range Test Poi nt 1–Ye a r L i m i t s
Minimum
(V)
Maximum
(V) Location Va l ue (V)
Lower Limit
(V)
Upper Limit
(V)
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

©National Instruments Corporation 9 NI 9219 Calibration Procedure
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. Create an AI thermocouple channel on the NI 9219. Configure the channel according to Table 6.
7. Acquire 20 unscaled I32 readings with the NI 9219. Record the average of the readings as
dataunscaled.
8. 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.
9. Perform the following calculation using the recorded Vref and Vchannel values.
10. Compare the calculation result to the Upper Limit and Lower Limit values in Table 7.
11. Set the source output to zero and clear the acquisition.
12. Repeat steps 2 through 11 for all test points and all channels on the NI 9219. NI recommends that
you verify the values for all the iterations listed in Table 7 for each channel, but you can save time
by verifying only the values and channels used in your application.
13. Disconnect the source and the DMM from the device.
Table 6. NI 9219 Configuration for Thermocouple Accuracy Verification
Measurement Type Min (°C) Max (°C) ADC Timing Mode Sample Timing Type
Thermocouple 0100 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 –=