Chart History buffer

[Slifer]

Hi,
Can any body guide me as to how to access the chart history data in the form of arrays?.. I have dynamic data in the chart history buffer and I need to access it to do standard deviation and mean.
Thanks.

[altenbach]

Create a propery node for your chart and get item "History data" (It is all the way at the bottom :)).

[Slifer]

Well.. i tried that before.. but since the data was dynamica and reala time, it didnt let me connect it to the standard deviation and mean vi. Any suggestions?.. I need to calculate it for 250 samples on the fly..

[altenbach]

Ahhh... dynamic data, something I don't use much.
( You're correct, it does not seem to work right using the history data, but maybe I am not doing it right. ;))

As an alternative, you could use a collector express VI with the buffer matched to the history data. See attached (LabVIEW 7.1).

[Slifer]

Hi..I have LabView 7.0.. any chance I can get the vi in the 7.0 version?..
Thanks

[altenbach]

Here you go! 🙂

[Slifer]

That was great. But I beleive we can get the same result by using Sd PtByPt and Mean PtbyPt vis and connecting the signal to it and mentioning the number of samples. What I actually had in mind was..for example get sd and mean for 250 samples, and repeat the same for consecutive 250 samples. The methods you and I are using currently gies sd and mean for say 1 to 250, 2 to 251,.. so on updating as sonn as it gets a new sample..if I am havingdata at 50 hz, the mean and sd should update every 5 seconds. But now it updates for every sample...Any more suggestions?
thanks