How can I dynamicall​y read a file and show/plot the data in the GUI?

Question

Hi, everyone,
I hope to implement a VI with the following function:
Usually, when we "read a file" in VI and then show the data in the Waveform Chart or other display GUI, the VI will first read and record all of the data from the file and then show them simultaneously. Now, I want to implement a VI, which could read  the data from a file and display it in a time series. That is, I can define a "sampling rate" or "reading rate", like 100 data points / second,  then the data points could be correspondingly shown in Waveform Chart one by one as the time moves on. The key purpose is to simulate a real-time data collection module using an existing file.
I don't know how to implement this function. Any suggestion and solution are really appreciated.
Thanks.
Zhanpeng

Answer 1

Heres the same effect, just a different approach :
The code in the red box was used to create data that you would be getting from a file.
What you could do is (shown above) :
- Read all of the data
- Index only one value at a time, and set the 'sampling rate' using a wait in a while loop.
- Build an array using this value, which will simulate collecting data in real time.
- I used an array of the iterations as X-values, because they coincidentally correspond to # seconds in my example
- I then bundled the time array (xvalues) with the values from your file (yvalues)
- Send that bundle to an XY graph
That should work, though you could implement some different logic for different sampling rates.
Let me know if you need a hand with that.
Message Edited by Cory K on 02-26-2009 11:36 AM
Cory K
Attachments:
graph from file.PNG ‏10 KB