Placement of cursor on a Waveform Graph?

[ccurtis]

Hello All,

   I know this may seem trivial to most, but I am struggling a bit with this one. I need to place the yellow cursor (cursor 0) on the left edge of the left rising edge of the white input trace. I have tried doing this using the Threshold 1D array function but cannot get it to work. If someone could provide a vi to demonstrate how I would go about accomplishing this I would really appreciate it! Or any explanation would be welcome. The input signal is coming from two retroreflective sensors attached to a National Instruments 2110 BNC box and a 6120 Multi Function Board. I am also attaching a Waveform Graph.jpg file so you can see where the cursor is and where I need it to be. Also for clarification I need it on the edge not just close. What I mean is when I use the Graph palette tool to zoom in on the trace no matter how  zoomed in it is the cursor needs to be on that left edge. Anyway I would be very thankful if someone could help me out with this!

Many Thanks,

Charlie

[mikeporter]

How about something like this?

Mike...

[ccurtis]

Hey Mike,

   How about something like that? That is exactly what I need and again you have made it look so easy. I knew I was missing something and I didn't think about the Min Max function. So again I say thank you for helping me out!

Thank You Very much,

Charlie

[mikeporter]

There are two aspects to that code, one of which is obvious because it's on the block diagram (finding the 50% point of the edge). The other not so obvious point is that the cursor is set to "lock to the plot". This setting locks the "cross hairs" to the data point closest to the X-axis value you specify. In other words, if our dataset doesn't have any datapoints on the edge, your results will not be quite so pretty.

That solution for that condition is a bit more complex.

Mike...

[Dennis_Knutson]

Another way to do this is with the Basic Trigger Level Detection function. The default setting for mode returns the index of the trigger location. You ca wire this to the Cursor.Index property.

[ccurtis]

Oh how right you are! Thanks to your piece of code though me and a couple of my compadres figured it out. So thanks for the update and the vi! It really did help!

Thanks,

Charlie

[ccurtis]

Hey Dennis,

   Thanks for the info. All information leads to the final answer. Anyway I appreate your efforts!

Thanks, Charlie