Achieve Maximum Sample Rate With NI Source Measure Unit (SMU)

Updated Aug 28, 2023



  • PXIe-4112
  • PXIe-4113
  • PXI-4132
  • PXIe-4135
  • PXIe-4136
  • PXIe-4137
  • PXIe-4138
  • PXIe-4139
  • PXIe-4140
  • PXIe-4141
  • PXIe-4142
  • PXIe-4143
  • PXIe-4144
  • PXIe-4145

This article will show how to achieve digitizer (scope) functionality and the maximum sample rate of your NI Source Measure Unit (SMU).

The digitizer functionality of NI SMUs is essential for capturing detailed transient characteristics of the SMU response or for characterizing device under test (DUT) behavior such as line and load transients. Without this functionality, you would need an external oscilloscope. 

As an example, assume you are using a PXIe-4139 in Single Point source mode. To use the digitizer functionality, you should configure SMU as below (also see the figure): 
  1. Measurement:Advanced:Measure When property should be set to On Measure Trigger
  2. Configure the Measure Record Length to a desired length (or infinite).
  3. Export the Start Trigger to /4139/PXI_Trig0.
  4. Set the Measure: Digital Edge input terminal to /4139/PXI_Trig0.
  5. Set the Measurement:Aperture Time to be close or equal to 0.

Step 3 and 4 intend to export the start event to trigger the measurement beginning. You can check PXIe-4139 Device Routes in MAX to see what routes are supported, if a different trigger source is desired.

Additional Information

In Sequence Source mode, the configuration is almost the same. Watch the fetch count; it should be the same as or less than Measure Record Length multiplied by step number.

Another implementation, created by modifying the NI-DCPower Measure Record example, is given below.  It has been tested on the PXIe-416x SMU devices.  When deciding which parameters and properties to tweak on the SMU, it is often easiest to start with the soft front panel in InstrumentStudio and once the desired results are seen, use those parameters or values in your LabVIEW program.
NI-DCPower Measure Record Mod