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FPGA: Is waveform graph or chart not available in fpga?

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I was trying to use waveform graph to display data in my fpga project. The source data type is fxp, however, when I connected the source to the waveform graph, it still shows DBL, which is not supported by fpga. There is no problem for I16 data type.


So is it possible to display fxp data array with waveform graph in fpga?

I'm very new to this, and thanks for your reply and patience.



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Hi rwthybw,


well, as there is no monitor connected to your FPGA (and it even does not allow for interactive frontpanels) it makes no sense to put graphs/charts on a FPGA VI frontpanel…


I guess you know things like this or that?

Best regards,

using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
Message 2 of 3
Accepted by rwthybw

Well, I don't know about the chart not making sense on FPGA, they are essentially just Scalars but with the LV display engine showing N history length...... They can be useful for debugging.  See below.


Graphs, since the data history must be handled on the FPGA itself, rarely makes sense.


But aside from that, Graphs and Charts need to plot Integers only on FPGA, FXP will coerce to SGL or (even worse since it's never supported : DBL).  You need to cast your FXP to the nearest Integer and plot (and interpret accordingly).  This significantly reduces the readability and usefulness during debugging.


CAVEAT: Charts on FPGA are a SINGLE value only (on FPGA).  Whatever speed LV Display engine receives data at will determine how the Chart is filled.  When running in Simulation mode, this can be every point (as things run really slowly).  With real hardware, this can be only every millionth point or so, depending on how fast the FPGA code is updating.  In contrast, Graphs actually buffer the data as an array on the FPGA (which requires lots of resources).  If you have respources to spare, Graphs will give you every single point in sequence (Since the data handling is also running at FPGA speed).

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