National Instruments PXIe-4357 Manual

CALIBRATION PROCEDURE
NI PXIe-4357
This document contains information about calibrating National Instruments PXIe-4357
SC Express modules using NI-DAQmx. For more information about calibration, visit ni.com/
calibration.
Contents
Software Requirements............................................................................................................. 1
Documentation Requirements .................................................................................................. 2
Calibration Interval................................................................................................................... 2
Test Equipment......................................................................................................................... 2
Test Conditions......................................................................................................................... 3
Calibration Procedure ............................................................................................................... 3
Initial Setup....................................................................................................................... 3
Connecting the Calibrator to the Module ................................................................. 4
Verification ....................................................................................................................... 5
4-Wire Accuracy Verification .................................................................................. 5
Adjustment Procedure ...................................................................................................... 7
Specifications............................................................................................................................ 9
Where to Go for Support .......................................................................................................... 10
Software Requirements
Install NI-DAQmx 9.5 or later on the calibration computer. NI-DAQmx includes high-level
function calls to simplify the task of writing software to calibrate modules. You must have the
proper module driver installed on the calibration system before calibrating the module.
Note NI recommends that you install the NI-DAQmx driver software before
physically installing the NI PXIe-4357. NI-DAQmx, available at ni.com/
downloads, configures and controls the NI PXIe-4357.
NI-DAQmx supports a number of programming languages, including LabVIEW,
LabWindows™/CVI™, C/C++, C#, and Visual Basic .NET.
ni.com/manuals
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Documentation Requirements
The following documents are your primary references for writing your calibration utility with
NI-DAQmx. You can download the latest version of these documents from the NI Web site at
ni.com/manuals.
• The NI PXIe-4357 and TB-4357 Installation Guide and Terminal Block Specifications
provides instructions for installing and configuring the NI PXIe-4357 module and TB-4357
accessory. This document also contains TB-4357 specifications.
• The NI PXIe-4357 User Manual describes how to use the NI PXIe-4357.
• The NI PXIe-4357 Specifications lists the specifications for the NI PXIe-4357.
• The NI-DAQmx Help includes information about creating applications that use the
NI-DAQmx driver.
• The NI-DAQmx C Reference Help includes information about the functions in the driver.
Calibration Interval
National Instruments recommends a calibration interval of one year for the NI PXIe-4357. 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 an
NI PXIe-4357 module.
Table 1. Recommended Equipment
Equipment Recommended Model(s) Requirements
Calibrator Fluke 5520A If this instrument is unavailable,
use a calibrator that can provide
resistance values in the range of
0Ωto 400 Ωwith 0.01 Ω
resolution, an accuracy of 90 ppm
or better, and automatic lead-wire
compensation.
PXI Express chassis NI PXIe-1062Q —
Connection accessory TB-4357 terminal block Screw terminal accessory for the
NI PXIe-4357.

© National Instruments Corporation |3
Test Conditions
The following setup and environmental conditions are required to ensure the device meets
published specifications:
• Keep connections to the module as short as possible. Long cables and wires act as antennae,
picking up extra noise that can affect measurements.
• Use shielded copper wire for all cable connections to the module. Use twisted-pair wire to
eliminate noise and thermal offsets.
• 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 measurement circuitry of the
module is at a stable operating temperature.
• Ensure that the PXI Express chassis fan speed is set to HIGH, that the fan filters are clean,
and that the empty slots contain filler panels. For more information, refer to the Maintain
Forced-Air Cooling Note to Users document available at ni.com/manuals.
Calibration Procedure
This section provides instructions for verifying the performance of the NI PXIe-4357.
The calibration process consists of the following steps:
1. Initial Setup—Install the module and configure it in Measurement & Automation Explorer
(MAX).
2. Verification—Verify the existing operation of the module. This step confirms whether the
module is operating within the published specifications prior to adjustment.
3. Adjustment Procedure—If necessary, perform an external calibration that adjusts the
module calibration constants with respect to a known calibration source.
4. Reverification—Repeat the verification procedure to ensure that the module is operating
within the published specifications after adjustment.
Initial Setup
You must configure the module in Measurement & Automation Explorer (MAX) to
communicate with NI-DAQmx.
Complete the following steps to configure a module in MAX. Refer to the NI PXIe-4357 and
TB-4357 Installation Guide and Terminal Block Specifications for complete installation
instructions.
1. Install the NI-DAQmx driver software.
Caution Always have the PXI Express chassis turned off when inserting a module.
2. Insert the module into an available slot in the PXI Express chassis.
3. Install the terminal block.
4. Power on the chassis.

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5. Launch MAX.
6. Expand Devices and Interfaces to confirm that MAX detects the module.
7. Right-click the module name and select Self-Test to ensure that the module is working
properly.
Note When a module is configured with MAX, it is assigned a module name. Each
function call uses this module name to determine which DAQ module to calibrate.
This document uses Dev1 to refer to the module name. In the following procedures,
use the module name as it appears in MAX.
Connecting the Calibrator to the Module
Refer to the specific verification or calibration procedure section for information describing the
required module connections. Each channel consists of a group of four pins specific to that
channel. Before connecting or disconnecting the calibrator from the module, always set the
calibrator to standby mode (STBY).
Refer to Figure 1 for the pin assignments of the TB-4357.
Figure 1. TB-4357 Pin Assignments
EX–
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
EX+
AI–
AI+
EX–
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
EX+
AI–
AI+
EX–
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
EX+
AI–
AI+
EX–
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
EX+
AI–
AI+
EX–
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
AI–
AI+
EX–
EX+
EX+
AI–
AI+
C H 0 C H 5 C H 10 C H 15 C H 1 C H 6 C H 11 C H 16 C H 2 C H 7 C H 12 C H 17 C H 3C H 8 C H 13C H 18 C H 4 C H 9 C H 14 C H 19
J2 J7
J8J3 J9J4
J10J5 J11J6
TB–4357 152646A–01L S/N
FOR PATENTS: NI.COM/PATENTS
COPYRIGHT 2011

© National Instruments Corporation |5
Refer to Table 2 for the analog signal names of the TB-4357.
Verification
Verification determines how well the module is meeting its specifications. By completing this
procedure, you can see how the module has drifted over time, which helps you determine the
appropriate calibration interval for your application. The NI PXIe-4357 has 20 independent
analog input channels. You can conduct verification on any or all of them, depending upon your
desired test coverage.
4-Wire Accuracy Verification
Complete the following steps to test the 4-wire accuracy of the module.
1. Set the calibrator to standby mode (STBY).
2. Make the following connections to the TB-4357 for the channel you want to verify. Refer
to Figure 2 for visual reference. Refer to the Connecting the Calibrator to the Module
section for the pin assignments and signal names of the TB-4357.
Figure 2. 4-Wire Accuracy Verification Connections
3. Zero the calibrator with the ohms-only zero (OHMS ZERO) operation. Refer to the
calibrator documentation for more information about zeroing the calibrator.
4. Set the calibrator output for 4-wire compensation (COMP 4-wire).
5. Set the calibrator resistance output to a 0 Ω.
6. Set the calibrator to operate mode (OPR).
7. Create a task.
Table 2. TB-4357 Analog Signal Names
Signal Names Signal Descriptions
EX– Excitation current return
EX+ Positive excitation current output
AI– Negative analog input
AI+ Positive analog input
Calibrator
HI
AUX HI
AUX LO
LO
TB-4357
CH X
EX+
AI+
AI–
EX–

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8. Create and configure an AI Resistance channel according to the values in Table 3.
9. Configure the timing properties for the task.
10. Start the task.
11. Acquire 10 points of data.
12. Average the readings that you acquired and record the result.
13. Clear the task.
14. Repeat steps 5 through 13 for all calibrator output values listed in Table 4. NI recommends
that you verify all values, although you can save time by verifying only the values used in
your application.
15. Compare the measured result for each value to the Upper Limit (
Ω )and Lower Limit ( Ω )
values in Table 4. If the results are all between these values, the module passes the test.
16. Set the calibrator to standby mode (STBY).
17. Disconnect the calibrator from the module.
18. Repeat steps 2 through 17 for every channel you want to verify.
Table 3. 4-Wire Configuration Values
Configuration Value
Channel Name Dev1/aix, where xrefers to the channel number
Min Input Limit 0
Max Input Limit 400
Units Ohms
Resistance Configuration 4-wire
Current Excitation Source Internal
Current Excitation Value 0.0009
Sample Clock Rate (Hz) 10
Sample Mode Finite Samples
Samples to Read 10

© National Instruments Corporation |7
Adjustment Procedure
Use the adjustment procedure to adjust the gain and offset calibration constants for each channel.
At the end of each calibration procedure, these new constants are stored in the external
calibration area of the EEPROM. These values are password-protected, which prevents the
accidental access or modification of any calibration constants adjusted by the metrology
laboratory. The default password is NI. You can calibrate as many or as few channel and
excitation configurations as desired. The calibration routine for the NI PXIe-4357 uses a
two-point calibration to determine the gain and offset adjustment calibration constants.
Complete the following steps to test the accuracy of the module.
1. Set the calibrator to standby mode (STBY).
2. Make the following connections to the TB-4357 for the channel you want to adjust. Refer
to Figure 3 for visual reference. Refer to the Connecting the Calibrator to the Module
section for the pin assignments and signal names of the TB-4357.
Note All connections shown in Figure 3 must be made using discrete connections.
Figure 3. Adjustment Connections
Table 4. 4-Wire Mode Accuracy Test Limits
Test Point (Ω)Lower Limit (Ω)Upper Limit (Ω)
0–0.034 0.034
50 49.946 50.054
100 99.926 100.074
150 149.906 150.094
200 199.886 200.114
250 249.866 250.134
300 299.846 300.154
350 349.826 350.174
400 399.806 400.194
Calibrator
HI
AUX HI
AUX LO
LO
TB-4357
CH X
EX+
AI+
AI–
EX–

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3. Zero the calibrator with the ohms-only zero (OHMS ZERO) operation. Refer to the
calibrator documentation for more information about zeroing the calibrator. This step can
be skipped if an OHMS ZERO has already been executed on the calibrator as required by
the calibrator for the specified accuracy.
4. Set the calibrator output for 4-wire compensation (COMP 4-wire).
5. Set the calibrator resistance output to 100 Ω. This is the first calibration point.
6. Set the calibrator to operate mode (OPR).
7. Open a calibration session on your module using the DAQmx Initialize External
Calibration VI. The default password is NI.
8. Call the DAQmx Adjust 4357 Calibration VI.
9. Set the calibrator to output a resistance of 350 Ω. This is the second calibration point.
10. Call the DAQmx Adjust 4357 Calibration VI.
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxInitExtCal with the following
parameters:
deviceName: Dev1
password: NI
calHandle: &calHandle
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxAdjust4357Cal with the
following parameters:
calHandle: calHandle
physicalChannel: Dev1/ai x , where x refers to
the channel number.
refValues: [100]
numRefValues: 1
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxAdjust4357Cal with the
following parameters:
calHandle: calHandle
physicalChannel: Dev1/ai x , where x refers to
the channel number.
refValues: [350]
numRefValues: 1

© National Instruments Corporation |9
11. Save the adjustment to the EEPROM, using the DAQmx Close External Calibration VI.
This VI also saves the date, time, and temperature of the adjustment to the onboard memory.
Note If an error occurs during adjustment, no constants will be written to the
EEPROM.
12. Repeat steps 1 through 11 for each channel to be adjusted.
13. Set the calibrator to standby mode (STBY).
14. Disconnect the calibrator from the module.
The module is now calibrated with respect to your external source. After calibrating the module,
you must reverify the accuracy of the module. To do this, repeat the Verification section.
Specifications
The specifications in Table 5 are provided for reference only, refer to the NI PXIe-4357
Specifications and NI PXIe-4357 User Manual for detailed specification and application
information. The values in Table 5 are based on calibrated scaling coefficients, which are stored
in the onboard EEPROM. The following calibration specifications are for 23 °C ±5 °C.
LabVIEW Block Diagram NI-DAQmx Function Call
Call DAQmxCloseExtCal with the following
parameters:
calHandle: calHandle
action: DAQmx_Val_Action_Commit
Table 5. NI PXIe-4357 Measurement Accuracy, 1 Year, 23 °C ±5 °C Max, 4-Wire Mode
Offset Error (Ω)Gain Error (% of Reading)
0.034 0.04

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Where to Go for Support
The National Instruments Web site 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.
National Instruments corporate headquarters is located at 11500 North Mopac Expressway,
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