Curve Fitting

[F._Schubert]

Well, I don't see any information in the DAQ assistant at all (no channel!) and the 1 Sample is most likly the default.

If you have the time to learn LV programming, then do us all a favour and try to get rid of the express vi's and the dynamic data type. You are able to convert the Express VIs to real code and then try to understand and replicate it. (right click: Open Front Panel).

To make LV working as a programming language, you need to go in the menu under tools->advanced->edit palette views and there switch from Express to Advanced.

For some reason, all experienced programmers have absolutly no knownledge about express VI's. Altenbach made a good LabToon on this one, I will see if I can find it. So if you get rid of the Express stuff, we suddenly will see more clearly what you're programming.

Felix

Edit: here is the LabToon

Message Edited by F. Schubert on 06-26-2009 10:09 AM

[RavensFan]

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clousekc wrote:

Can you show me an example or something of how I could go about doing what you described Ravens Fan?  I can't seem to figure out how you are just seeing the one sample going into the curve fitting.  I'm not saying that's not what is happening.  It's just my DAQ Assistant is set on continuous sampling, so the waveform graph aside shouldn't the sampling remain continuous?  If I take out the express vi for curve fitting my lvm file has a lot more than just one data point.  I guess what I'm saying is that when I put the curve fitting vi into my vi is when things go bad.  Why would the express vi only take one data point when there should be many?  Does the input for the curve fitting have to be an array then instead of just a straight 'data feed'?  I apologize for my lack of knowledge, but again everything I do know about Labview is from playing around or reading help menus.

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See attached.  You have a waveform chart not a waveform graph.  A chart maintains history, a graph does not.

You LVM will show multiple points because it will add the new data point on every iteration.

Have you changed your VI any since the one you posted in reply #11?

[clousekc]

I haven't changed it since that post other than messing with settings on the express vi's.  From your screenshot it appears that something is changing when you open my vi.  I have attached a screenshot of when I open the DAQ Assistant.  I will also try to upload a ' program' version of the vi which Felix spoke of.

[F._Schubert]

Ah, great. You will need N Samples instead of continous.

Continous with 100 samples means that you have a buffer of 100 samples, but the vi returns only values that are available at the moment you run it (so might be less than 100, maybe less than 6).Or you query how many are available (there is a DAQmx property node for this.

It will be more easy if you program in DAQmx instead of Express, as the DAQmx Read function will give you the level of control you need...

Felix

[RavensFan]

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clousekc wrote:
I haven't changed it since that post other than messing with settings on the express vi's.  From your screenshot it appears that something is changing when you open my vi. 

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Exactly.  You must have changed that particular express VI.  The settings in Express VI's aren't supposed to change settings when someone else opens them up.  If they do, then you found a serious bug.

Try downloading your file attachment from #11 again and open it.  See what settings you have.

[clousekc]

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Ravens Fan wrote:

Exactly.  You must have changed that particular express VI.  The settings in Express VI's aren't supposed to change settings when someone else opens them up.  If they do, then you found a serious bug.

Try downloading your file attachment from #11 again and open it.  See what settings you have.

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I downloaded it and it was the same thing as I have been saying which is different from your screen shot.  I don't know if maybe this is due to the version difference or the fact that I have the chasis and module hooked up to my pc.

[F._Schubert]

This DAQ assistant behaviour is 'normal' in the LV 7 generation. The settings are stored in the instr.lib folder (if i remember correctly). This is annoying, as I wont get it copied using a Developement distribution for testing on the machine with the hardware. One of the reasons I use express things only for protoyping and keep that outside of the real code.

But correct behaviour would be, that the express Vi is broken (or link broken).

Anyhow, the error results from the assistant returning immediatly with 0 or 1 data points on the first call. Several ways to solve that issues where posted above.

Felix

[RavensFan]

That's good to know.  Now I know neither of us are crazy.  That is a very bad behavior to have for the reasons being demonstrated in all of these posts.  I'm glad is was fixed in later versions.