How Do I Use "Write Data" to Store a Non-Time Based 2D Array in a TDM File?

[mloisell]

I have a 2D array of frequencies vs. amplitudes. I'd like to use the Write Data [Channel] Express VI to store the data in a TDM file for later use in DIAdem, but the Write Data VI seems to want only a time-based signal, and automotically inserts a Convert to Dynamic Data (CDD) bullet when I wire the array to the Write Data VI. The closest property in the CDD bullet that I can see is the "2D array of scalars - rows are channels", however, that's not really what I need, since the first row of data is my list of frequencies and the second row of data is my amplitudes.

The frequencies are spaced at regular intervals, so if there's a way to trick the Write Data VI into treating the frequencies as times, that may work for me.

I've attached a JPG image of a little piece of what I've been trying to do.

Thanks in advance for the help!

--
Matt

[mloisell]

Oops. I forgot the image.

[AESulzer]

Matt,

The only way to associate an "x-axis" with a signal in the Write Data VI would be to feed it waveforms, which are constrained to use time as the x-axis unit. There is really no way around this, so in my opinion, the best solution for you would be to use the "rows are channels" conversion and write the frequency and amplitude values to the file independently. Then when you read the file in DIAdem, take the two channels and build a graph out of them there.

Regards,

E. Sulzer
Applications Engineer
National Instruments

[mloisell]

Thanks! I realized this morning that I'd be better off doing just that for my application anyway since all the amplitude arrays use the same frequency array, so it doesn't make much sense for me to keep saving the same set of frequencies. I can save them as the first channel and use them for all the amplitude data.

Thanks!!