National Instruments NI PXIe-4138 Manual

CALIBRATION PROCEDURE
NI PXIe-4138
Single-Channel System Source-Measure Unit (SMU)
This document contains the verification and adjustment procedures for the
National Instruments PXIe-4138 (NI 4138). Refer to ni.com/calibration for more information
about calibration solutions.
Contents
Software Requirements............................................................................................................. 1
Related Documentation.............................................................................................................2
Password................................................................................................................................... 2
Calibration Interval................................................................................................................... 3
Test Equipment..........................................................................................................................3
Test Conditions..........................................................................................................................3
As-Found and As-Left Limits................................................................................................... 4
Calibration Overview................................................................................................................5
Verification................................................................................................................................6
Self-Calibrating.................................................................................................................6
Voltage and Current Verification.......................................................................................6
Adjustment.............................................................................................................................. 15
Adjusted Specifications...................................................................................................15
Initiating the Adjustment Session................................................................................... 15
Voltage and Current Output............................................................................................ 16
Residual Offset Voltage...................................................................................................20
Closing the Adjustment Session..................................................................................... 20
Alternative to Adjustment Procedures............................................................................ 20
Reverifying..............................................................................................................................21
Worldwide Support and Services............................................................................................ 21
Software Requirements
Calibrating the NI 4138 requires the following software on your system. All required NI
software is available at ni.com/downloads.
• NI-DCPower 1.9 or later
• Supported application development environment (ADE)—LabVIEW or
LabWindows™/CVI™
• Supported operating system—Windows

When you install NI-DCPower, you need to install support only for the application software
that you intend to use. Access calibration support in the locations shown in the following table.
ADE Calibration Support Location
LabVIEW NI-DCPower Calibration palette
LabWindows/CVI NI-DCPower function panel (niDCPower.fp)
Related Documentation
Consult the following documents for information about the NI 4138, NI-DCPower, and your
application software. Visit ni.com/manuals for the latest versions of these documents.
Table 1. Documentation Locations and Descriptions for Calibration
Document Location Description
NI DC Power Supplies
and SMUs Getting
Started Guide
Available from the Start menu
and at ni.com/manuals.
Contains instructions for
installing and configuring NI
power supplies and SMUs.
NI DC Power Supplies
and SMUs Help
Available from the Start menu
and in HTML format at
ni.com/manuals.
Contains detailed information
about the NI 4138 and NI-
DCPower LabVIEW VI and C
function programming
references.
NI PXIe-4138
Specifications
Available from the Start menu
and at ni.com/manuals.
Contains the published
specification values for the
NI 4138.
NI-DCPower Readme Available from the Start
menu.
Contains operating system and
application software support in
NI-DCPower.
LabVIEW Help Available by selecting Help»
LabVIEW Help from within
LabVIEW or at ni.com/
manuals.
Contains LabVIEW
programming concepts and
reference information.
Password
The default password for password-protected operations is NI.
2| ni.com | NI PXIe-4138 Calibration Procedure

Calibration Interval
............................................................................Recommended calibration interval 1 year
Test Equipment
The following table lists the equipment NI recommends for the performance verification and
adjustment procedures. If the recommended equipment is not available, select a substitute
using the minimum requirements listed in the table.
Table 2. Required Equipment for Calibration
Required
Equipment
Recommended
Model(s)
Parameter
Measured
Minimum Specifications
Digital
multimeter
(DMM)
Agilent 3458 A All parameters
except remote
sense accuracy
Voltage: < ±9 ppm
accuracy and < 100 nV
resolution. Current: <
±25 ppm accuracy and <
10 pA resolution.
1 MΩ current
shunt
IET Labs SRL-1M 1 μA and 10 μA
current accuracy
< 4 ppm accuracy, <
0.2 ppm / °C tempco.
1 Ω current shunt Ohm Labs CS-1 1 A current
accuracy
<65 ppm accuracy, <
5 ppm / °C tempco.
333 mΩ current
shunt
Ohm Labs CS-3 3 A current
accuracy
< 120 ppm accuracy, <
5 ppm / °C tempco.
3 kΩ resistor Vishay
PTF563K0000BYEB
Remote sense
accuracy
0.1% 250 mW
Test Conditions
The following setup and environmental conditions are required to ensure the NI 4138 meets
published specifications:
• Keep cabling as short as possible. Long cables act as antennas, picking up extra noise that
can affect measurements.
• Verify that all connections to the device, including front panel connections and screws,
are secure.
• Ensure that the PXI chassis fan speed is set to HIGH, that the fan filters (if present) are
clean, and that the empty slots contain slot blockers and filler panels. For more
NI PXIe-4138 Calibration Procedure | © National Instruments | 3

information about cooling, refer to the Maintain Forced-Air Cooling Note to Users
document available at ni.com/manuals.
• Allow a warm-up time of at least 30 minutes after the chassis is powered on and NI-
DCPower is loaded and recognizes the NI 4138. Allow adequate warm-up time for all
other instruments and equipment according to the manufacturer instructions. The warm-
up time ensures that the NI 4138 and test instrumentation are at a stable operating
temperature.
• Use shielded copper wire for all cable connections to the device. Use twisted-pair wire to
eliminate noise and thermal offsets.
• To ensure the system has had adequate time to settle, wait one second after requesting a
new current or voltage or after changing a load before taking a measurement.
• Keep relative humidity between 10% and 70%, noncondensing.
• Test limits in this document are based on the December 2013 edition of the NI PXIe-4138
Specifications, except for more recently revised remote sense test limits.
• When making measurements, set the niDCPower Aperture Time property or
NIDCPOWER_ATTR_APERTURE_TIME attribute to 2 power-line cycles (PLCs) on the
device. Set the niDCPower Aperture Time Units property or
NIDCPOWER_ATTR_APERTURE_TIME_UNITS to power line cycles.
• Do not use the NI-DCPower Soft Front Panel (SFP) to request test points for any
adjustment functions because you cannot set aperture time using the SFP.
• Ensure that properties or attributes for the device that are not specified in calibration
procedures are set to their default values.
• When making measurements, configure any specified digital multimeters (DMMs) with
the best available levels and limits for each specified test point.
Temperature conditions specific to verification procedures:
• Maintain an ambient temperature of 23 °C ± 5 °C. Maintain an internal device
temperature range of Tcal ± 5 °C.1
Temperature conditions specific to adjustment procedures:
• Maintain an ambient temperature of 23 °C ± 1 °C. The NI 4138 internal temperature will
be greater than the ambient temperature.
As-Found and As-Left Limits
The as-found limits are the published specifications for the device. NI uses these limits to
determine whether the device meets the device specifications when it is received for
calibration.
1Tcal is the internal device temperature recorded by the NI 4138 at the completion of the last self-
calibration. Call the niDCPower Get Self Cal Last Temp VI to query Tcal from the NI 4138.
4| ni.com | NI PXIe-4138 Calibration Procedure

The as-left limits are equal to the published NI specifications for the device, less guard bands
for measurement uncertainty, temperature drift, and drift over time. NI uses these limits to
determine whether the device will meet the device specifications over its calibration interval.
Calibration Overview
Calibration includes the steps shown in the following figure.
Figure 1. Calibration Overview
Document
Post-Adjustment
Results
Document
Pre-Adjustment
Results
Calibration/
Verification
Complete
Yes No
Meets
Calibration
Test Limits?
Review Verification/
Adjustment Procedure
or Return Device
Verify
Adjust (Calibration Constants,
Dates, and Temperatures
Updated)
Verify
1. Initial Setup—Install the NI 4138 and configure it in Measurement & Automation
Explorer (MAX) .
2. Verification—Verify the existing operation of the NI 4138. This step confirms whether
the device is operating within the published specifications prior to adjustment.
3. Adjustment—Adjust the calibration constants of the NI 4138.
4. Reverification—Repeat the Verification procedure to ensure that the device is operating
within the published specifications after adjustment.
Refer to the following sections to complete each procedure.
NI PXIe-4138 Calibration Procedure | © National Instruments | 5

Verification
The performance verification procedures assume that adequate traceable uncertainties are
available for the calibration references.You must complete all verification procedures in the
specified order.
Self-Calibrating
Complete the following steps to self-calibrate the device.
1. Disconnect or disable all connections to the device.
2. Ensure the device had 30 minutes to warm up with the PXI chassis fans set to HIGH.
3. Initialize an NI-DCPower session.
4. Call the self-calibration function.
5. Close the NI-DCPower session.
Voltage and Current Verification
You do not need to separately verify or adjust both measurement and output. The architecture
of the NI 4138 ensures that if measurement is accurate, then output is as well, and vice versa.
Connecting and Configuring Equipment for Voltage Verification
1. Make the necessary connections for this procedure, as shown in the following figure.
Figure 2. Voltage Verification or Adjustment Connection Diagram
DMM
Voltage
Mode
+
–
NI-DCPower Device
Sense LO
Sense HI
HI
LO
2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Voltage for the NI 4138.
Verifying Voltage Measurement and Output
Compare a set of voltages measured by an external DMM to the voltage test points requested
by the NI 4138.
Verify ranges in the specified order.
Refer to the following table as you complete the following steps.
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Table 3. Voltage Output and Measurement Verification
Level
Range
Limit
Range and
Limit
Test Point As-Found
Measurement Test
Limit (% of Voltage +
Offset)
As-Left Measurement
Test Limit (% of Voltage
+ Offset)
600 mV 1 mA -600 mV 0.02% + 100 μV 0.0065% + 25 μV
0 mV
600 mV
6 V 1 mA -6 V 0.02% + 600 μV 0.0045% + 85 μV
0 V
6 V
60 V 1 mA -60 V 0.02% + 6 mV 0.0065% + 820 μV
0 V
60 V
1. Set the first specified level range, limit range, and limit on the NI 4138.
2. Measure the internal device temperature and perform self-calibration if necessary.
a) If the internal device temperature exceeds Tcal ± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within Tcal ± 1 °C.
b) If after 5 minutes the stable temperature still exceeds Tcal ± 1 °C, call the self-
calibration VI or function.
3. Set the level on the NI 4138 to the first specified test point.
4. Compare a DMM voltage measurement to the voltage measurement test limits.
a) Take a voltage measurement using the DMM.
b) Calculate the lower and upper voltage measurement test limits using the following
formula: Voltage Measurement Test Limits = Test Point ± (|Test Point| * % of
Voltage + Offset ).
c) Verify the DMM measurement falls within the test limits.
5. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
6. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Verifying Voltage Remote Sense
Use the NI 4138 in constant current mode with a test circuit to simulate the voltage drop
between the device and a load.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
NI PXIe-4138 Calibration Procedure | © National Instruments | 7

Refer to the following table as you complete the following steps.
Table 4. Voltage Remote Sense Output Verification
Level
Range
Limit Range
and Limit
Test Point Load1Load2Voltage Remote Sense Test
Limit
Load1Load2
1 mA 600 mV 0 mA 3 kΩ 3 kΩ ≤38.4 µV ≤6 µV
1 mA
1. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Current for the NI 4138.
2. Set the niDCPower Sense property or NIDCPOWER_ATTR_SENSE attribute to Remote.
3. Make the necessary connections for this procedure, as shown in the following figure.
Figure 3. Voltage Remote Sense Diagram, Part 12
NI-DCPower Device
Sense LO
Sense HI
HI
LO
Load1
4. Set the first specified level range, limit range, and limit on the NI 4138.
5. Measure the internal device temperature and perform self-calibration if necessary.
a) If the internal device temperature exceeds Tcal ± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within Tcal ± 1 °C.
b) If after 5 minutes the stable temperature still exceeds Tcal ± 1 °C, call the self-
calibration VI or function.
6. Set the level on the NI 4138 to the first specified test point.
7. Take a voltage measurement using the NI 4138.
8. Record the voltage from the previous step as V1.
9. Repeat the previous three steps for the other test point specified in the range. This time,
record the value as V2.
10. Calculate the remote sense error using the following formula: Remote Sense Error = |V2 -
V1|. Record the value.
2Follow industry best practices for minimizing thermal electromotive force (EMF) when making the
necessary connections for this procedure.
8| ni.com | NI PXIe-4138 Calibration Procedure

11. Verify that the recorded value falls within the test limits.
12. Repeat the previous steps. This time, make the necessary connections as shown in the
following figure:
Figure 4. Voltage Remote Sense Diagram, Part 23
NI-DCPower Device
Sense LO
Sense HI
HI
LO
Load2
Verifying Offset Current
Remove all connections from the NI 4138 and confirm the current measured by the NI 4138 at
0 V falls within the test limits.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
Refer to the following table as you complete the following steps.
3Follow industry best practices for minimizing thermal electromotive force (EMF) when making the
necessary connections for this procedure.
NI PXIe-4138 Calibration Procedure | © National Instruments | 9

Table 5. Current Offset Verification
Level
Range
Limit
Range and
Limit
Test
Point
As-Found Offset Test
Limit
As-Left Offset Test Limit
Lower Limit Upper
Limit
Lower Limit Upper
Limit
600 mV 1 μA 0 mV -200 pA 200 pA -25 pA 25 pA
10 µA -1.4 nA 1.4 nA -200 pA 200 pA
100 µA -12 nA 12 nA -1.5 nA 1.5 nA
1 mA -120 nA 120 nA -15 nA 15 nA
10 mA -1.2 μA 1.2 μA -150 nA 150 nA
100 mA -12 μA 12 μA -1.5 μA 1.5 μA
1 A -120 μA 120 μA -15 μA 15 μA
3 A -1.8 mA 1.8 mA -500 μA 500 μA
1. Disconnect all equipment from the output of the NI 4138.
2. Measure the internal device temperature and perform self-calibration if necessary.
a) If the internal device temperature exceeds Tcal ± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within Tcal ± 1 °C.
b) If after 5 minutes the stable temperature still exceeds Tcal ± 1 °C, call the self-
calibration VI or function.
3. Take a current measurement using the NI 4138.
4. Record the value from the previous step.
5. Verify that the recorded value falls within the test limits.
6. If more than one limit range is specified, repeat the previous steps using the values
specified in each limit range.
Verifying 1 μA and 10 μA Current Measurement and Output
Compare a set of measured currents reported by the NI 4138 to the currents measured by an
external DMM.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
1. Refer to the following table as you complete the following steps.
10 | ni.com | NI PXIe-4138 Calibration Procedure

Table 6. 1 µA and 10 µA Current Output and Measurement Verification
Level
Range
Limit
Range and
Limit
Shunt Test Point As-Found
Measurement Test
Limit (% of Current +
Offset)
As-Left
Measurement Test
Limit (% of Current +
Offset)
6 V 1 µA 1 MΩ -0.9 V 0.03% + 200 pA 0.013% + 25 pA
0.9 V
60 V 10 µA -9 V 0.03% + 1.4 nA 0.013% + 200 pA
9 V
2. Make the necessary connections for this procedure, as shown in the following figure.
Figure 5. Current Connection Diagram, Part 1
NI-DCPower Device
Sense LO
Sense HI
HI
LO
+
–
Precision
Shunt
DMM
Voltage
Mode
3. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Voltage for the NI 4138.
4. Set the first specified level range, limit range, and limit on the NI 4138.
5. Measure the internal device temperature and perform self-calibration if necessary.
a) If the internal device temperature exceeds Tcal ± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within Tcal ± 1 °C.
b) If after 5 minutes the stable temperature still exceeds Tcal ± 1 °C, call the self-
calibration VI or function.
6. Set the level on the NI 4138 to the first specified test point.
Complete the following 4 steps within 5 minutes or less of completing the previous step
in order to ensure the internal device temperature remains stable.
7. Calculate the current through the shunt by completing the following steps.
a) Take a voltage measurement across the shunt using the DMM.
b) Divide the voltage measurement by the calibrated value of the shunt.
c) Record the calculated value as DMM Measured Current.
NI PXIe-4138 Calibration Procedure | © National Instruments | 11

8. Calculate the lower and upper current measurement test limits using the following
formula: Current Measurement Test Limits = DMM Measured Current ± (|DMM
Measured Current| * % of Current + Offset ).
9. Disconnect the DMM. Leave the NI 4138 output on.
Figure 6. Current Connection Diagram, Part 2
Sense LO
Sense HI
HI
LO
Precision
Shunt
NI-DCPower Device
10. Take a current measurement using the NI 4138.
11. Record the value from the previous step.
12. Verify that the recorded NI 4138 value falls within the test limits.
13. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
14. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Verifying 100 μA to 100 mA Current Measurement and Output
Compare a set of currents measured by an external DMM to the current test points requested
by the NI 4138.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
Refer to the following table as you complete the following steps.
Table 7. 100 µA to 100 mA Current Output and Measurement Verification
Level Range Limit
Range and
Limit
Test Point As-Found
Measurement Test
Limit (% of Current +
Offset)
As-Left Measurement
Test Limit (% of
Current + Offset)
100 µA 6 V -100 µA 0.03% + 12 nA 0.013% + 1.5 nA
100 µA
12 | ni.com | NI PXIe-4138 Calibration Procedure

Table 7. 100 µA to 100 mA Current Output and Measurement Verification (Continued)
Level Range Limit
Range and
Limit
Test Point As-Found
Measurement Test
Limit (% of Current +
Offset)
As-Left Measurement
Test Limit (% of
Current + Offset)
1 mA 6 V -1 mA 0.03% + 120 nA 0.013% + 15 nA
1 mA
10 mA 6 V -10 mA 0.03% + 1.2 μA 0.013% + 150 nA
10 mA
100 mA 6 V -100 mA 0.03% + 12 μA 0.013% + 1.5 μA
100 mA
1. Make the necessary connections for this procedure, as shown in the following figure.
Figure 7. Current Verification Connection Diagram
NI-DCPower Device
Sense LO
Sense HI
HI
LO
DMM
Current
Mode
+
–
2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Current for the NI 4138.
3. Set the first specified level range, limit range, and limit on the NI 4138.
4. Measure the internal device temperature and perform self-calibration if necessary.
a) If the internal device temperature exceeds Tcal ± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within Tcal ± 1 °C.
b) If after 5 minutes the stable temperature still exceeds Tcal ± 1 °C, call the self-
calibration VI or function.
5. Set the level on the NI 4138 to the first specified test point.
6. Compare a DMM current measurement to the current measurement test limits.
a) Take a current measurement using the DMM.
NI PXIe-4138 Calibration Procedure | © National Instruments | 13

b) Calculate the lower and upper current measurement test limits using the following
formula: Current Measurement Test Limits = Test Point ± (|Test Point| * % of
Current + Offset ).
c) Verify the DMM measurement falls within the test limits.
7. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
8. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Verifying 1 A and 3 A Current Measurement and Output
Compare a set of currents measured by an external DMM to the current test points requested
by the NI 4138.
Complete this procedure only after successfully completing all previous verification
procedures. Verify ranges in the specified order.
Refer to the following table as you complete the following steps.
Table 8. 1 A and 3 A Current Output and Measurement Verification
Level
Range
Limit
Range and
Limit
Shunt Test
Point
As-Found
Measurement Test
Limit (% of Current
+ Offset)
As-Left
Measurement Test
Limit (% of Current
+ Offset)
1 A 6 V 1 Ω -1 A 0.03% + 120 μA 0.013% + 15 μA
1 A
3 A 6 V 333 mΩ -3 A 0.06% + 1.8 mA 0.045% + 500 μA
3 A
1. Make the necessary connections for this procedure, as shown in the following figure.
Figure 8. Current Verification Connection Diagram
NI-DCPower Device
Sense LO
Sense HI
HI
LO
+
–
Precision
Shunt
DMM
Voltage
Mode
14 | ni.com | NI PXIe-4138 Calibration Procedure

2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Current for the NI 4138.
3. Set the first specified level range, limit range, and limit on the NI 4138.
4. Measure the internal device temperature and perform self-calibration if necessary.
a) If the internal device temperature exceeds Tcal ± 1 °C, wait up to 5 minutes for the
temperature to stabilize to within Tcal ± 1 °C.
b) If after 5 minutes the stable temperature still exceeds Tcal ± 1 °C, call the self-
calibration VI or function.
5. Set the level on the NI 4138 to the first specified test point.
6. Calculate the current through the shunt by completing the following steps.
a) Take a voltage measurement across the shunt using the DMM.
b) Divide the voltage measurement by the calibrated value of the shunt.
c) Record the calculated value as DMM Measured Current.
7. Calculate the lower and upper current measurement test limits using the following
formula: Current Measurement Test Limits = Test Point ± (|Test Point| * % of Current +
Offset ).
8. Verify that the recorded DMM value falls within the test limits.
9. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
10. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Adjustment
This section describes the steps needed to adjust the device to meet published specifications.
Following the adjustment procedure automatically updates the calibration date and
temperature on the device.
Adjusted Specifications
Adjustment corrects the following specifications for the device:
• Voltage programming accuracy
• Current programming accuracy
• Voltage measurement accuracy
• Current measurement accuracy
Note You do not need to separately verify or adjust both measurement and output.
The architecture of the NI 4138 ensures that if measurement is accurate, then output
is as well, and vice versa.
Initiating the Adjustment Session
1. After completing verification, wait a minimum of 5 minutes for the internal device
temperature to stabilize.
NI PXIe-4138 Calibration Procedure | © National Instruments | 15

2. Initiate an external calibration session (a special type of NI-DCPower session) by calling
the niDCPower Initialize External Calibration or niDCPower_InitExtCal function.
3. Call the self-calibration function.
Ensure the following conditions during adjustment:
• Keep the calibration session open until you complete all adjustment procedures.
• Complete all adjustment procedures within 15 minutes or less after initiating the external
calibration session.
• Complete all adjustment procedures in the specified order.
• Do not self-calibrate the device except as specified in a procedure.
Voltage and Current Output
Connecting and Configuring Equipment for Voltage Adjustment
1. Make the necessary connections for this procedure, as shown in the following figure.
Figure 9. Voltage Verification or Adjustment Connection Diagram
DMM
Voltage
Mode
+
–
NI-DCPower Device
Sense LO
Sense HI
HI
LO
2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Voltage for the NI 4138.
Adjusting Voltage Output and Measurement
Compare a set of voltages measured by an external DMM to the voltage test points requested
by the NI 4138.
Refer to the following table as you complete the following steps.
16 | ni.com | NI PXIe-4138 Calibration Procedure

Table 9. Voltage Output and Measurement Adjustment
Level Range Limit Range and Limit Test Point
6 V 100 mA 5 V
-5 V
1. Set the first specified level range, limit range, and limit on the NI 4138.
2. Set the level on the NI 4138 to the first specified test point.
3. Take a voltage measurement using the DMM.
4. Store the value from the previous step as input for the niDCPower Cal Adjust VI or
function called in the following steps.
5. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
6. Update the output calibration constants by configuring and calling the niDCPower Cal
Adjust Voltage Level VI or niDCPower_CalAdjustVoltageLevel function.
a) Input the DMM measurements as the measured outputs.
b) Input the test points as the requested outputs.
c) Input the specified level range as the range.
7. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Adjusting 1 μA to 100 mA Current Output and Measurement
Complete this procedure only after successfully completing all previous adjustment
procedures. Adjust ranges in the specified order.
Refer to the following table as you complete the following steps.
Table 10. 1 µA to 100 mA Current Output and Measurement Adjustment4
Level Range Limit Range and Limit Test Point
100 µA 6 V 100 µA
-100 µA
1 mA 6 V 100 µA5
-100 µA
1. Make the necessary connections for this procedure, as shown in the following figure.
4Adjusting the 100 µA and 1 mA level ranges automatically adjust the following ranges: 1 μA,
10 µA, 10 mA, and 100 mA.
5The NI 4138 requires that you verify ±100 µA test points in the 1 mA level range.
NI PXIe-4138 Calibration Procedure | © National Instruments | 17

Figure 10. Current Output and Measurement Adjustment Connection Diagram
NI-DCPower Device
Sense LO
Sense HI
HI
LO
DMM
Current
Mode
+
–
2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Current for the NI 4138.
3. Set the first specified level range, limit range, and limit on the NI 4138.
4. Set the level on the NI 4138 to the first specified test point.
5. Take a current measurement using the DMM.
6. Store the value from the previous step as input for the niDCPower Cal Adjust VI or
function called in the following steps.
7. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
8. Update the output calibration constants by configuring and calling the niDCPower Cal
Adjust Current Limit or niDCPower_CalAdjustCurrentLimit function.
a) Input the DMM measurements as the measured outputs.
b) Input the test points as the requested outputs.
c) Input the specified level range as the range.
9. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
Adjusting 1 A and 3 A Current Output and Measurement
Compare a set of measured currents reported by the NI 4138 to the currents measured by an
external DMM.
Complete this procedure only after successfully completing all previous adjustment
procedures. Adjust ranges in the specified order.
Refer to the following table as you complete the following steps.
18 | ni.com | NI PXIe-4138 Calibration Procedure

Table 11. 1 A and 3 A Current Output and Measurement Adjustment
Level Range Limit Range and Limit Shunt Test Point
1 A 6 V 1 Ω 1 A
-1 A
3 A 6 V 333 mΩ 3 A
-3 A
1. Make the necessary connections for this procedure, as shown in the following figure.
Figure 11. Current Output and Measurement Adjustment Connection Diagram
NI-DCPower Device
Sense LO
Sense HI
HI
LO
+
–
Precision
Shunt
DMM
Voltage
Mode
2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Current for the NI 4138.
3. Set the first specified level range, limit range, and limit on the NI 4138.
4. Set the level on the NI 4138 to the first specified test point.
5. Calculate the current through the shunt by completing the following steps.
a) Take a voltage measurement across the shunt using the DMM.
b) Divide the voltage measurement by the calibrated value of the shunt.
6. Store the value from the previous step as input for the niDCPower Cal Adjust VI or
function called in the following steps.
7. Repeat the previous steps, from setting the level to the test point on the NI 4138 up to this
step, for each specified test point in the level range.
8. Update the output calibration constants by configuring and calling the niDCPower Cal
Adjust Current Limit or niDCPower_CalAdjustCurrentLimit function.
a) Input the DMM measurements as the measured outputs.
b) Input the test points as the requested outputs.
c) Input the specified level range as the range.
9. If more than one level range is specified, repeat the previous steps using the values
specified in each level range.
NI PXIe-4138 Calibration Procedure | © National Instruments | 19

Residual Offset Voltage
Connecting and Configuring Equipment to Adjust Residual
Offset Voltage
1. Make the necessary connections for this procedure, as shown in the following figure.
Figure 12. Residual Voltage Offset Diagram
NI-DCPower Device
Sense LO
Sense HI
HI
LO
2. Set the niDCPower Output Function property or NIDCPOWER_OUTPUT_FUNCTION
attribute to DC Voltage for the NI 4138.
Adjusting Residual Voltage Offset
Short the NI 4138 terminals and call the appropriate VI or function.
Complete this procedure only after successfully completing all previous adjustment
procedures.
Eliminate residual offset voltage at 0 V by configuring and calling the niDCPower Cal
Adjust Residual Voltage Offset VI or niDCPower_CalAdjustResidualVoltageOffset
function.
Closing the Adjustment Session
Close the session and commit the new constants to hardware by calling the niDCPower
Close External Calibration VI or niDCPower_CloseExtCal function and specifying
Commit as the calibration close action.
Alternative to Adjustment Procedures
If your device passes all verification procedures successfully and you want to skip updating
the calibration constants, you can update solely the calibration date by completing the
following steps.
Note National Instruments recommends following all adjustment procedures in
order to update the calibration constants and renew the device calibration interval.
20 | ni.com | NI PXIe-4138 Calibration Procedure