calculating time delay between two signals aquired from DAQ

[Dennis_Knutson]

You didn't do any of the things I suggested. Here's an image.

Message Edited by Dennis Knutson on 02-19-2009 08:14 AM

[hussain]

thanks for the suggestion but when i subtract the both trigger locations than it shows me some value which i dont think so is in time(sec) format.

should i need to add FOR loop to count the number delays occured when ever trigger happens form both signals, because as u know i am aquiring  continues signals from DAQ?  

[Dennis_Knutson]

Why don't you think it's in seconds. Did you ever stop to consider that you will get a negative time if the trigger point of signal 1 is earlier than the trigger point of signal 2?. You made the VI with the subtraction in it. By looking at that, I would assume that the trigger point of signal 2 is earlier. Is that true or not? This is pretty basic arithmetic.

Message Edited by Dennis Knutson on 02-21-2009 12:31 PM

[Pladio]

Hi,

I know this thread is old, but I didn't think I should start a new one.

I'm quite new to labView and I basically need to measure the same thing. The drawing below seems quite like a good implementation. 

I was hoping someone could tell me where I find those trigger boxes ? I searched inside the Pallet, but I can't find them.

Thank you.

[Dennis_Knutson]

Did you click on the Search button that is on the functions palette? The name has been given (Basic Level Trigger Detection). In any case, its on the Signal Processing>Waveform Measurements>Waveform Monitoring palette.

You also need at least the Full version of LabVIEW.

[Pladio]

Hello again,

Thank you for such a swift reply. Your code seems to be working. Unfortunately, there seems to be something wrong with mine as I'm getting a delay of -3.40491E+9 which seems very high ... (unless this is in nanoseconds)

Oh well, I'll have a play around and try to figure out an answer for a while before coming back and ask here again.

Just to point out, I was using the Search, but looking for Trigger, not Basic Level Trigger Detection. The triggers weren't what I was looking for.

Thanks again 🙂

Also how important is the Kudos thing for people here ?

[RavensFan]

That size of number sounds like the number of seconds since midnight January 1, 1904 GMT.  For me, that is 11:20:00 AM 11/23/2011 EST.

You are probably getting an actual trigger time from one, and no trigger from the other, and subtracting the current time from 0 to get that number.

Kudoes are important.  It is a way of saying thank you and giving recognition to the people who have helped you.  The kudoes count is one of the items that factors into the colored bars that ranks you as a member of the forums.

[Pladio]

I just checked. I get 0.1 as a trigger from one and 3.4E9 from the other.

Am I supposed to get a trigger as a time from the start (1904 ...) or just a point ?

[Dennis_Knutson]

You should get a relative time - not one from 1904. No trigger detected should return 0 and the Boolean output would of course be false.

Create a graph indicator for the DAQ signal and run the VI, making sure the signal is visible in the graph. Then, go to the Edit menu and select 'Make Current Values Default'. Save the VI and attach it.

[Pladio]

Here.

Thanks for your time.