Waveform Chart value property

[Ilya K]

Hello Folks:

Just a general question about using the property nodes with Waveform Charts.

I'm trying to write a 1D array of waveforms to a Chart to display using the chart's property node, but it keeps returning "An input parameter is invalid" error.

Aside from the performance issues of updating charts this way, this should be a very simple and straightforward code. It works file if I try to display scalar values or a single waveform. However, it doesn’t work for an array of waveforms. Also, just wiring the array of waveforms to the Chart indicator directly works well.

The sample vi is attached. This is one part of the code that I’m trying to adapt from 7.1 to 8.0. It was working fine in LabVIEW 7.1 but it breaks in 8.0.

Can anyone tell me what might be the issue here?

Appreciate all help,

-Ilya.

[becktho]

Hi

I can't tell you why it worked in LV7.1 and now it doesn't. I had a look at the vi and wondered why you want to use a chart. Basically, the chart offers functionality to just put in a single value (or a 1D array) and see the trend, as the control buffers the values. If you wire a waveform to the chart, still have this feature, but I don't think this is useful.

[Ilya K]

Hi becktho:

As I said, this little vi was lifted from a bigger program. That program has one data acquisition loop that reads data from a DAQ card and stores it in a queue. Then another loop gets the data from the queue and sends it to the chart and lover rate.

But aside from that (yes, in that vi it would be extreamly simple to just wire the waveforms directly), the code should still work. But it doesn't.
Do you see any mistakes in it?

-Ilya.

[Joe_H]

I can confirm that it does work in 7.0 and 7.1 but not in 8.0 and it should. I think we have found a bug in the chart.

[JLS]

Hello,

You are absolutely correct that it should work - it is a known bug and will be addressed for future version of LabVIEW.  I know that's a standard answer - we just don't have authorization to say more on the discussion forums.  What I can tell you though, is that this is known and being addressed!

Thank you,

Best Regards,

JLS

[Ilya K]

Well, since it was determined that the described effect is really a bug that will be fixed sometime in the future, is there an elegant solution to go around this?

Thanks so much,

-Ilya.