cursor

[star-123]

Hi Everybody,

I would like to read x value which related half of the waveform. for this, I created cursor in graph. y value of cursor is equal half of amplitude and it is determinated automatically.  I want to read x value which the cursor is breakpoint the signal. also, I want that x value of cursor  is determinated automatically. for this what can I do?

[altenbach]

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@1085 wrote:

I want to read x value which the cursor is breakpoint the signal.

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What does that mean?

To do measurements on data, you don't need to use cursors and graphs, just use plain math in the diagram.

Can you attach a simple VI that contains a typical waveform. Also tell us that result you expect from the given data. What is the datatpye?

[star-123]

I attached the VI. while y value of cursor is half of amplitude, I want that x value is read automatically. for this, What can I do?

[RavensFan]

Cursor.PosX property

[altenbach]

As I said, you should not rely on the cursor, esecially since you allow it to be dragged by the user. If you want to find the point where the data is at half-max for the first time, use threshold array and move the cursor there. See attached.

If the data is more complicated, you might need to tweak a little bit.

[star-123]

Ok.  I want to find the point where the data is at half-max for the second time. for this, What can I do?

[srikrishnaNF]

Hi 1085,

 If you can able to get the whole waveform as an array(you can use GetWaveForm components.vi ),then you can search for the max value in the array for all indices.

Regards,

Srikrishna.J

[altenbach]

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@1085 wrote:

Ok.  I want to find the point where the data is at half-max for the second time. for this, What can I do?

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If you want to catch the transition on the downslope you need to search again. Easiest is to start searching at the index of the max, but negate the data and threshold so you get an increasing curve for that segment.

You could also just subtract the half-max amplitude from the data and search for zero transitions. (i.e. places where the sign changes, then interpolate to get the fractional position).