how to find x axis value corresponding to a given y axis value in a graph

[shivy92]

Here is my vi again after making the value default. 

regards.

[Taki1999]

You've got quite a bit going on there and I think you're going through a lot of extra work to use the Dynamic Data Types and Express XY Graph.

Here's one way to get what you want though.

From your XY Graph, Index out the first (and only) plot.

Unbundle to get the Y and X Arrays. By a quirk of LabVIEW XY Graph, both of these are named Y. The first one is actually X.

Do an Array Max Min on Y to get the Index of the largest Y value.

Pass that Index into Array Index of X to get the X value.

[Taki1999]

Also, I don't think your Build XY Graph is configured correctly.

As it is now, you only graph the first channel of your data.

The rest of your data is truncated since your X array is only 1-D 512 elements.

[.aCe.]

I am not entirely sure if this is what you are looking for, give it a go.