SubVI is not executable in PXIe-7965R:

[Bnyam]

I develop a SubVI (please see the screenshot “NDFT_FPGA” attached to this request) that performs a non-uniform FFT using Dynamic-Link library (dll) written in c and LabVIEW. The SubVI is added to FPGA data board (A PXIe-7965R) to calculate non-uniform fft of a signal acquired from a photodetector (New Focus 1817).

The SubVI has three inputs and one output: first input is called vandermonde matrix and its size1024 x 1024, second input is called weight vector, its 1x2014 vector .Both inputs are in .csv format stored in the host PC, and the SubVI is reading them using “Read Delimited Spreadsheet.vi” function. The third input is a vector coming from the photodetector of our system.

 A PXIe-7965R is attached to a NI5761 CLIP and it is acquiring the signal coming from a photodetector. The signal is stored in a FIFO called DataTargetFIFO (please see the screenshot “NDFT_FPGA” attached to this request) then in the “SS-OCT” case structure, the first for loop constructs an array of length 1024 and this array is sent to the SubVI and the SubVI produces output array which will be saved in a FIFO called the PostTargetFIFO element by element, after that  the whole procedure will be repeated by constructing a new array of length 1024, send to the SubVI, then the output is saved in the PostTargetFIFO and so on.

Now the LabVIEW produces an error saying SubVI is not executable and the error particularly refers to the “Read Delimited Spreadsheet.vi” function in the SubVI. However, when I check and run the SubVI separately, it works. So can you please help me solving this error . Thanks in advance.

NI Software: LabVIEW Professional Development System version 2011 SP1.

NI Hardware : PXIe-7965R device

OS: Window 7

[GerdW · Accepted solution]

Hi Bnyam,

the FPGA neither can do any file operation nor will it call any DLL!

You need to develop your subVI specifically for your FPGA target with functions supported on the FPGA!

- While you are busy to do so: the FPGA doesn't support any DBL datatypes. Either use FXP or SGL!

- It also doesn't support 2D arrays. You need to stick with fixed-sized 1D arrays!

[RavensFan · Accepted solution]

Your subVI calls a dll.  DLL's work on Windows.  They don't work on an FPGA.

Secondarily, I do not believe you can have floating point numbers on an FPGA.

Also, an FPGA does not have a file system, so how wold you ever be able to read a file using the Read Spreadsheet File?

Make sure you create your FPGA VI's within a project under the FPGA target, and only use functions available in that FPGA palette.

[Bnyam]

Thank you so much GerdW & RavensFan for your help and informations.

[Philippe_RSA]

Magic !

I am also looking for a non-uniform FFT (dll with labview wrapper).

Please can you share your dll with your vi.

(without FPGA of course)