Using FPGA Extensions with RFmx

RFmx EV-DO 19.1 Help

Edition Date: October 2019

Part Number: 375499H-01

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RFmx EV-DO 19.1 Help
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To use NI-RFSA instrument driver FPGA extensions with RFmx, you must install NI-RFSA along with RFmx and the latest version of LabVIEW. When you install NI-RFSA, a model-specific folder for your device is created in the following location:

  • Windows 8/7: Users\Public\Documents\National Instruments\FPGA Extensions Bitfiles

For RFmx to recognize your precompiled bitfile, ensure that the precompiled bitfile is located in the model-specific folder that corresponds to your device.

Note Note  The NI 5624R is supported by RFmx only as part of the NI 5668R VSA. Refer to the NI IF Digitizers Help, located at, for more information about using the NI 5624R as a stand-alone device.

NI 5668R Pre-installed FPGA Bitfiles

NI-RFSA includes two FPGA bitfiles for use with the NI 5668R in a separate directory from the directories listed in the previous section. The NI 5668R default 400 MHz bitfile and the optional 800 MHz bitfile are located in the following directory:

  • Windows 8/7: ProgramData\National Instruments\FPGA Extensions Bitfiles\NI PXIe-5624R

Loading an FPGA Bitfile

To use RFmx with NI-RFSA instrument driver FPGA extensions, you must specify the precompiled bitfile you want to use when you initialize the RFmx session. If you want to access additional FPGA functionality provided by the precompiled bitfile, you must also obtain an FPGA reference to use with the LabVIEW FPGA host interface.

Note Note  You can load only one bitfile on a device at a time. If you are using both RFmx and another device driver such as NI-RFSA or NI-RFSG to simultaneously access the same instrument, both sessions must initialize with the same bitfile.

Complete the following steps to open an instrument driver session that uses a precompiled bitfile:

  1. Call the RFmxInstr Initialize NIRFSA VI.
  2. Wire the RFmx Setup string to the Option String input.
  3. Include the Bitfile tag in the RFmx Setup string, and set the value of the Bitfile tag to the name of the bitfile you want to load, as shown in the following example string:


    where filename.lvbitx is the filename of the bitfile you want to load.

Obtaining an FPGA Reference

Complete the following steps to obtain an FPGA reference to use with the LabVIEW FPGA host interface:

  1. Obtain the NI RFSA Session using RFmxInstr Get NIRFSA Session VI.
  2. Read the FPGA Bitfile Path property using the NI-RFSA Session. The FPGA Bitfile Path property returns the absolute path to the bitfile as a string.
  3. Wire the output of the FPGA Bitfile Path property to the String input of the String to Path function.
  4. Wire the Path output of the String to Path function to the Bitfile Path input of the Open Dynamic Bitfile Reference function.

The following figure illustrates how the code might look after completing the preceding steps.


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