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

Updated Feb 15, 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 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 infinate).
  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. There are other ways. You can check PXIe-4139 Device Routes in MAX to see what routes are supported.

Additional Information

In Sequence source mode, the configurations are almost the same. Watch out the fetch counts though. It should be the same with or less than Measure Record Length multiplied by step number.

A C# example for setting your SMU to maximum sample rate is attached to this KB.