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 Contains instructions for and at ni.com/manuals. installing and configuring NI power supplies and SMUs. NI DC Power Supplies and SMUs Help Available from the Start menu Contains detailed information and in HTML format at about the NI 4138 and NIni.com/manuals. DCPower LabVIEW VI and C function programming references. NI PXIe-4138 Specifications Available from the Start menu Contains the published and at ni.com/manuals. 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 NIDCPower is loaded and recognizes the NI 4138. Allow adequate warm-up time for all other instruments and equipment according to the manufacturer instructions. The warmup 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. 1 4 | Tcal is the internal device temperature recorded by the NI 4138 at the completion of the last selfcalibration. Call the niDCPower Get Self Cal Last Temp VI to query Tcal from the NI 4138. 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 Pre-Adjustment Results Verify Adjust (Calibration Constants, Dates, and Temperatures Updated) Document Post-Adjustment Results Verify Yes Calibration/ Verification Complete Meets Calibration Test Limits? No Review Verification/ Adjustment Procedure or Return Device 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 NI-DCPower Device HI Sense HI Sense LO + DMM Voltage Mode – 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. 6 | ni.com | NI PXIe-4138 Calibration Procedure Table 3. Voltage Output and Measurement Verification Level Range 600 mV Limit Test Point Range and Limit 1 mA -600 mV As-Found Measurement Test Limit (% of Voltage + Offset) As-Left Measurement Test Limit (% of Voltage + Offset) 0.02% + 100 μV 0.0065% + 25 μV 0.02% + 600 μV 0.0045% + 85 μV 0.02% + 6 mV 0.0065% + 820 μV 0 mV 600 mV 6V 1 mA -6 V 0V 6V 60 V 1 mA -60 V 0V 60 V 1. 2. 3. 4. 5. 6. Set the first specified level range, limit range, and limit on the NI 4138. 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 selfcalibration VI or function. Set the level on the NI 4138 to the first specified test point. 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. 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. 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 1 mA Limit Range and Limit 600 mV Test Point Load1 Load2 0 mA 3 kΩ 3 kΩ Voltage Remote Sense Test Limit Load1 Load2 ≤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. Set the niDCPower Sense property or NIDCPOWER_ATTR_SENSE attribute to Remote. Make the necessary connections for this procedure, as shown in the following figure. 2. 3. Figure 3. Voltage Remote Sense Diagram, Part 12 NI-DCPower Device HI Sense HI Load1 Sense LO LO 4. 5. Set the first specified level range, limit range, and limit on the NI 4138. 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 selfcalibration 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. 2 8 | Follow industry best practices for minimizing thermal electromotive force (EMF) when making the necessary connections for this procedure. 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 HI Sense HI Sense LO Load2 LO 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. 3 Follow 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 600 mV Limit Range and Limit Test Point 1 μA 0 mV As-Found Offset Test Limit As-Left Offset Test Limit Lower Limit Upper Limit Lower Limit Upper Limit -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 1A -120 μA 120 μA -15 μA 15 μA 3A -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 selfcalibration 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. 10 Refer to the following table as you complete the following steps. | ni.com | NI PXIe-4138 Calibration Procedure Table 6. 1 µA and 10 µA Current Output and Measurement Verification Level Range 6V Limit Shunt Test Point As-Found As-Left Range and Measurement Test Measurement Test Limit Limit (% of Current + Limit (% of Current + Offset) Offset) 1 µA 1 MΩ -0.9 V 0.03% + 200 pA 0.013% + 25 pA 0.03% + 1.4 nA 0.013% + 200 pA 0.9 V 60 V 10 µA -9 V 9V 2. Make the necessary connections for this procedure, as shown in the following figure. Figure 5. Current Connection Diagram, Part 1 NI-DCPower Device + HI Sense HI Sense LO Precision Shunt DMM Voltage Mode – LO 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 selfcalibration 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 NI-DCPower Device HI Sense HI Precision Shunt Sense LO LO 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 6V -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 6V -1 mA 0.03% + 120 nA 0.013% + 15 nA 0.03% + 1.2 μA 0.013% + 150 nA 0.03% + 12 μA 0.013% + 1.5 μA 1 mA 10 mA 6V -10 mA 10 mA 100 mA 6V -100 mA 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 HI Sense HI Sense LO + DMM Current Mode – LO 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 selfcalibration 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) c) Calculate the lower and upper current measurement test limits using the following formula: Current Measurement Test Limits = Test Point ± (|Test Point| * % of Current + Offset ). 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) 1A 6V 1Ω -1 A 0.03% + 120 μA 0.013% + 15 μA 0.06% + 1.8 mA 0.045% + 500 μA 1A 3A 6V 333 mΩ -3 A 3A 1. Make the necessary connections for this procedure, as shown in the following figure. Figure 8. Current Verification Connection Diagram NI-DCPower Device + HI Sense HI Precision Shunt Sense LO LO 14 | ni.com | NI PXIe-4138 Calibration Procedure 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. 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 selfcalibration 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 NI-DCPower Device HI Sense HI Sense LO + DMM Voltage Mode – 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 6V 100 mA 5V -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 6V 100 µA -100 µA 1 mA 100 µA5 6V -100 µA 1. Make the necessary connections for this procedure, as shown in the following figure. 4 5 Adjusting the 100 µA and 1 mA level ranges automatically adjust the following ranges: 1 μA, 10 µA, 10 mA, and 100 mA. The 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 HI Sense HI Sense LO + DMM Current Mode – LO 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 1A 6V 1Ω 1A -1 A 3A 6V 333 mΩ 3A -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 + HI Sense HI Sense LO Precision Shunt DMM Voltage Mode – LO 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 HI Sense HI Sense LO 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 1. 2. Call one of the following: • niDCPower Initialize External Calibration VI • niDCPower_InitExtCal function Call one of the following, specifying Commit in calibration close action: • niDCPower Close External Calibration VI • niDCPower_CloseExtCal function Reverifying Repeat the Verification section to determine the as-left status of the device. If no as-left test limits are specified in a procedure, reuse the as-found test limits. Note If any test fails reverification after performing an adjustment, verify that you have met the Test Conditions before returning the device to NI. Refer to Worldwide Support and Services for more information about support resources or service requests. Related Information Test Conditions on page 3 Verification on page 6 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. Worldwide Support and Services The National Instruments website 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. Visit ni.com/services for NI Factory Installation Services, repairs, extended warranty, and other services. Visit ni.com/register to register your National Instruments product. 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For telephone support outside the United States, visit the Worldwide Offices section of ni.com/niglobal to access the branch office websites, which provide up-to-date contact information, support phone numbers, email addresses, and current events. Refer to the NI Trademarks and Logo Guidelines at ni.com/trademarks for information on National Instruments trademarks. Other product and company names mentioned herein are trademarks or trade names of their respective companies. For patents covering National Instruments products/technology, refer to the appropriate location: Help»Patents in your software, the patents.txt file on your media, or the National Instruments Patent Notice at ni.com/patents. You can find information about end-user license agreements (EULAs) and third-party legal notices in the readme file for your NI product. Refer to the Export Compliance Information at ni.com/legal/export-compliance for the National Instruments global trade compliance policy and how to obtain relevant HTS codes, ECCNs, and other import/export data. NI MAKES NO EXPRESS OR IMPLIED WARRANTIES AS TO THE ACCURACY OF THE INFORMATION CONTAINED HEREIN AND SHALL NOT BE LIABLE FOR ANY ERRORS. U.S. Government Customers: The data contained in this manual was developed at private expense and is subject to the applicable limited rights and restricted data rights as set forth in FAR 52.227-14, DFAR 252.227-7014, and DFAR 252.227-7015. © 2014 National Instruments. All rights reserved. 374137A-01 Sep14