Programmatically make horizontal cursor track the trace.

[crichter]

I have graphs of (X,Y) cordinates (5, 0.19), (10, 0.38) & (20,0.78) respectively. In my VI labeled AA, the horizontal cursor tracks perfectly from 5 to 10 and not so well from 10 to 20. This is just as one would expect, since the slope from 10 to 20 has changed slightly. In vi labeled AB, I have made the code calculate the new slope and would expect correct tracking from 10 to 20. I was only able to achieve tracking by including a 0.4848 offset and even then it is not exact. A 0.38 offset might be understandable, but at present I cannot explain the error. I wish to understand this so that I can increase the complexity of my graphs and then experiment with "in range and co-erce". Any guidance would be much appreciated.

graph 3 points AA.vi

graph 3 points AB.vi

[Ravi Beniwal]

Is there a reason why you want to calculate the cursor position and make it follow the plot instead of just letting the cursor snap to the plot?

[crichter]

That is a fair question Ravi. I wish view to the Y value at various values of X. Before my attempt to control the horizontal cursor, I could simply type my X value into the cursor legend and the the vertical cursor would snap to that value (e.g. 14.4). I would then have to drag the horizontal cursor to the intersection of the trace and the vertical cursor. If I choose "snap to plot" from cursor properties, both cursors will only snap to values I have put into an array.

[Ravi Beniwal]

OK, that makes sense. I changed your code; now (I think) it does exactly what you are looking for.

Cursor Traces Plot.vi

[crichter]

Thanks for digging deeper for me Ravi. Unfortunately I cannot view the changes, as I only have version 7.0

[Ravi Beniwal]

Sorry for the delayed response. LabVIEW 8.0 is about as far back as I can go. I've attached the file again saved in 8.0.

Cursor Traces Plot.vi

Can someone with LabVIEW 8.x please save this VI in 7.0?