data acquisition

[devchander]

Either at the end of the iteration or at the beginning of the iteration, put a property of for the Waveform chart, Set its property as>>Histroy data and wire an empty array to it

See attached VI

[kgy]

Thank you so much.! But would you please give me an image instead of vi file? I can't open it because of version problem. Thanks!

[S_Hong]

Hi kgy,

I figured I just open the VI and give you a snapshot of the block diagram.

Message Edited by S_Hong on 08-28-2008 04:05 PM

[devchander]

Thanks S_Hong

[kgy]

Thanks a lot, S-Hong!

[kgy]

oh, I still have problem wiring the array with the history properties. Please see attachment. How should I modify?

[devchander]

kgy,

Do not connect a dbl array

Instead, right click on the property node>> pop down menu>>create>> constant

Now, you would have wired a blank 1D array of Dynamic data

Look at attached pic

[kgy]

I think something is wrong here. I can't select creating a constant here because it is greyed out. Please check : right-click on the waveform chart to create a property node - click to select "history data"- right-click "change to write",-right-click, create-"constant"(but unfortunately it is greyed out).

For wiring it with the loop, I create another history data element, and then change it to read before wiring it with the while loop. In this case, will the waveform chart be refreshed at the beginning of the loop or at the end? What I am trying to do is to have an empty chart when starting the data collection. Then the chart displays all the data collected until stop. Please advice. Many thanks.

[S_Hong]

Hi kgy,

I am not exactly sure why you are unable to create a constant for your History Data. Could you try creating a control instead and see what kind of data type you get?

As for wiring the property node to the while loop, the reason we do this is to ensure that this property gets executed before entering the loop. As with any structure in LabVIEW, the loop structure will only start once all its inputs have been acquired, in this case, the error handle.

[kgy]

It works now! Thanks a lot!