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Seeing Steps in The Current Measurement On My I-V Graph

Primary Software: LabVIEW Development Systems>>LabVIEW Full Development System
Primary Software Version: 1.0
Primary Software Fixed Version: N/A
Secondary Software: Driver Software>>NI-DMM
Hardware: Modular Instruments>>Digital Multimeters (DMM)>>PXI-4071

Problem:
I am using a Source Measure Unit (SMU) to perform a voltage sweep by programmatically incrementing the voltage output value. I am also using a NI PXI Digital Multimeter (DMM) to measure the current going through my unit under test. Why am I seeing steps in my I-V graph when it should be a smooth sweep?

Solution:
The auto-range feature that is built into many of our DMMs for voltage and current measurements could be causing the steps you're seeing in your I-V graph. Depending on the model you are using, there may be multiple ranges your DMM uses whenever performing your measurements. The automatic adjustment of the range may be causing the steps to appear in the resulting values. If you know what ranges you are expecting, you can correct this issue by setting the Range terminal on the NI-DMM vis to be properly selected for your desired range for your measurement.

DMMs have different ranges available depending on the model so please reference the specifications manual for your card to determine what ranges are available. Setting the value manually will disable the auto feature and should make the steps disappear.

This solution is assuming that the I-V graph you are viewing is retrieving its voltage data from the incremented value occuring within the program for the Voltage axis and is retrieving its current values from the measurement performed by the DMM.

Related Links:
NI PXI-4071 PXI Digital Multimeter
NI PXI-4130 Source Measure Unit
NI 4071 Specifications Manual

Attachments:





Report Date: 05/05/2009
Last Updated: 05/05/2009
Document ID: 4X4ARV8H

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