04-24-2007 10:16 PM
04-25-2007 01:55 AM
As far as I know the XY Chart displays only the provided data and no older stuff. So you might have to change "XY Chart Buffer.VI" and add a clearing functionality (I have LV 8.2 and could not find this VI).
A workaround to clear the XY Chart is to use the Invoke Node Function "Reinitialize To Default" if the default is an empty chart.
Regards Jörn
04-25-2007 02:21 AM
Hello James,
i have 8.2 and could not find the xybuffer.vi you refer to. i would guess you constructed this subvi. send it so we could see what do you do in there.
however, you generally have simpe ways of displaying data: i understand the first channel is x, while the second is y? if so, use a shift register to keep the 2 separate arrays growing, and at each iteration (or every 20), just display them in a xy graph. this graph is then fed only with the data in the arrays. this is the short and dirty way of doing it, but you can begin there to see that it works. if it answers your question, you could continue and use an action engine, as refered by Ben:
http://forums.ni.com/ni/board/message?board.id=170&message.id=240328, to have unrelated data writing and reading.
but from what i see in your vi, the two DAQ inputs seems to be only y values (correct me if i am wrong). then you should just use charts instead of graphs, from which you can clear the history using a property node at begining of VI.
Does it help?
Gabriel
04-25-2007 05:13 AM
04-25-2007 11:09 AM
Hi,
thanks for all the comments and sorry about the XY buffer.vi....I attached it below. This VI came with Labview in the following library:
C:\Program Files\National Instruments\LabVIEW 8.0\examples\general\graphs\charts.llb\XY Chart Buffer.vi
Yeah I should clarify that pretty much what I would like to do is display the data (where each point is an averaged value) from the two channels as an xy graph as the points are generated.
Gabriel, I was initially trying to do what you said but as I thought about it, I think it would be preferrable (i.e. cooler!) if the user could see the data update on the chart as it is acquired. I tried to do this with a waveform but couldn't get it to work....
Right now I'm looking into changing the XY buffer VI and use the Invoke node as suggested by Jörn.
best,
James
04-25-2007 01:59 PM
Ok so I scrapped the XY buffer VI as I couldn't figure out how to get it to clear correctly...
So using Gabriels suggestion I used shift registers and it works the way I need it too.....should have tried this first aye!
thanks for the help
04-26-2007 01:47 AM