NI USB FPGA 7845R: Windows-only Support vs. Real-Time Requirements – Need Solution

[amrkzp]

Hi NI Community,

I’m reaching out because I need to achieve real-time control using the NI USB FPGA 7845R, and I’m running into some challenges that I hope someone can help me resolve.

The Issue:

• The NI USB FPGA 7845R is supported only on Windows.
• My application demands precise, deterministic timing—true real-time control.
• The current setup uses a labview host VI that communicates with the FPGA via DMA FIFOs, but this host VI runs on Windows.
• Our high-level controller runs on real-time Ubuntu and communicates with the host VI via UDP.
• The bottleneck is the host VI, which, running on Windows, cannot guarantee the required real-time performance.

What I’ve Found So Far:

• The device’s driver and software stack are strictly Windows-based.
• Windows cannot provide the determinism needed for our control application due to these delays.

What I’m Looking For:

• Is there any workaround or method to run the host VI on a real-time operating system, or otherwise mitigate these delays?
• Has anyone successfully achieved deterministic timing with a similar setup, or are there alternative solutions you’d recommend?

I appreciate any insights or suggestions you might have. Thanks in advance for your help!

[altenbach]

The LabVIEW FPGA module requires windows to program the fabric and all real-time control should probably happen inside the FPGA. I don't think UDP communication is suitable for "real-time control". (Sorry, I am not familiar with this device)

I have the feeling that the realtime forum would be more suitable for this discussion. Let me know if I should move this thread.

[amrkzp]

Thank you for your response. Yes, please move this thread to the real-time forum.

[ZYOng]

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@amrkzp wrote:

What I’m Looking For:

• Is there any workaround or method to run the host VI on a real-time operating system, or otherwise mitigate these delays?
• Has anyone successfully achieved deterministic timing with a similar setup, or are there alternative solutions you’d recommend?

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Unfortunately no. That's the limitation of a USB-based R Series device. If you need the RT determinism, you should get a PCI(e) or PXI(e) based module instead.

Other possible workarounds:

• Implement all control algorithm instead FPGA.
• Implement a MicroBlaze soft processor on FPGA, but this requires knowledge on Xilinx Vivado Toolkit and C programming. See fpganow/MicroBlaze_UART: How to use LabVIEW FPGA with a MicroBlaze soft-core processor and to commun...

[amrkzp]

Thanks for the suggestions.

I’m curious if it’s possible to mitigate the Windows-induced delays using a real-time extension like IntervalZero RTX64. From what I understand, RTX64 can provide a deterministic, real-time layer on top of Windows. Has anyone had any experience running labview using RTX64 (or similar solutions)?