Re : Report the X position at which an XY graph plot crosses a defined point on the Y axis using a cursor

[DarrenOdea]

Hi,

I am looking to automatically display the X co-ordinate at which a plot crosses a predefined point on the Y axis. I believe that this could be done manually by using a cursor on the graph. 

I am plotting the gain response of a low pass filter over a swept frequency range of 1000Hz and wish to determine the cut off frequency value (X axis) of the filter at the corresponding filter gain value of -3dB (Y axis). I am aware that I can create a cursor and manually drag it to the -3dB point and note the corresponding X value. However, I was wondering if there is a way that this can be performed automatically after each run with the corresponding value displayed in an indicator ?

That is to say that the Y value of the cursor be static and the X value follow the plot and report the X value at which it crosses the determined Y value.

Any help or advice that you could provide would be greatly appreciated.

I have included a copy of my VI below for clarity.

[GiulianoFranchetto · Accepted solution]

Hi,

1 subVI is missing. At the moment, i think you can just play with the property nodes of cursors to make them automatically go to the cut off frequency, and show the X value in an indicator. Here is an example:

here are the results

[DarrenOdea]

Thanks Giuliano, much appreciated