Continuously acquire, analyze, and plot data

[LVhelpME]

Dennis

I am aware of the chart history, what I am looking for is to display data in the graph as it is acquired, similar, to real-time.  What is happening now in the chart is the board acquires all the data , then plots it after the run has finished. 

Thanks again

Chris

Message Edited by LVhelpME on 01-10-2009 03:22 PM

[Dennis_Knutson]

A chart DOES NOT display all of the data when the loop finishes. A chart DOES display the data as it is acquired. It displays all of the samples you request as far as I can tell. As I said, I cannot run your VI without modifications. I deleted the subVI that does the file read, changed to continuous mode, and made the chart history a bit larger. You still have not attached the text files you are reading. And why would you want to read them with every iteration of your loop?

[LVhelpME]

Dennis

Thank you again for all the help, I think I found a fundamental flaw in what I am actually trying to do with this, and for it, I would not even need the while loop.

I have N channels, N samples being taken, and once those N samples have been taken, the VI will actually finish. I suppose I do not even need the while loop for that. What this whole thread has been working towards has been - is it possible to plot those N samples while they are being acquired, perhaps with buffers of some sort? I appologize for such an ignorant blunder on my part, and thank you again for the help.

Also, I would have attached the text files that you need, but I am not at the computer that has the VI on it now.

Chris

Message Edited by LVhelpME on 01-11-2009 06:24 PM

Message Edited by LVhelpME on 01-11-2009 06:28 PM

[Dennis_Knutson · Accepted solution]

I still am not sure what you mean by 'displaying as they are acquired'. The way a data acquisition card works, all of the requested samples are returned at once. If you have a sample rate of 10000 samples/sec and request 1000 samples, every .1 seconds you will get those 1000 samples displayed. If you request 10000 samples at the same rate, every 1 second you will get those 10000 samples displayed. If you are asking if at the 10000 samples/sec rate (for examples), you can have the chart display a sample every .0001 second, then no, you can't do that and I'm not sure why that would be necessary. If you wanted a much slower sample rate (something greater than 1 msec for example), then you could do a single point acquitisiton and display each point as it is acquired.

[LVhelpME]

Dennis

That was quick, I wasn't expecting an answer so late on a Sunday, thanks for the quickness.  That is what I was looking for, our sampling rate is in the neighborhood of 50-100 Hz, but because our application is picky about accurate timing over a long period of time, I would rather stick with the n channels, n samples.  I appreciate all the help you gave me, I am not sure how I could have gotten through these programs without the help of you and everyone else who responded to my posts.

Thanks

Chris