What is the Relationship Between Large Vector Memory (LVM), Source Memory, and Capture Memory in a PXIe-6570/6571?

Updated Dec 17, 2025

Reported In

Hardware

  • PXIe-6570
  • PXIe-6571

Driver

  • NI-Digital Pattern Driver

Issue Details

What is the Relationship Between Large Vector Memory (LVM), Source Memory, and Capture Memory in a PXIe-6570/6571? How can I choose which memory to use? Does using one limit the other?

Solution


Large Vector Memory (LVM), source memory, and capture memory are separate and do not impact each other. LVM is where the pattern is stored. Source memory is used to generate the data that is going to each pin, as defined by the pattern. Capture memory is used to capture the data into memory. 

The amount of memory in the LVM, capture memory, and source memory can be found on the specifications sheet of the device:

Additional Information

When writing a pattern that uses source memory, use a D instead of a 1 or 0 and use the opcode: Source. Create a source waveform and write it into source memory. Every time the pattern is run, the D indicates the pattern should use the next bit out of source memory. Source waveforms can either be in serial or parallel. You can create the source waveform in a variety of ways, such as creating it with LabVIEW. The LabVIEW example for creating and bursting a waveform is called NI-Digital Source Waveform.vi.

To use capture memory, use a V instead of a 1 or 0 and use the opcode: capture. Every time the pattern is run, the V indicates the pattern should capture the next sample. Source waveforms can either be in serial or parallel. The LabVIEW example for capturing a waveform is called NI-Digital Capture Waveform.vi.

You can find these examples, as well as other NI-Digital examples by going to: Help>>Find Examples...>>Hardware Input and Output>>Modular Instruments>> NI-Digital Pattern Driver.

For more detailed information on using Sourcing and Capturing Waveforms, see the manual for your device: