Graph Zooming Issue

[gammalight]

Hi everyone!

I just wanted to introduce myself to the forum and say that I think it is awesome there is a forum for people to talk about labview. I have used labview on and off for about 2 years and everything I know I have learned on my own. I like using labview more than traditional programming languages but find it hard to do some tasks.

I have one particular problem that does not make sense to me, but I was hoping one of you may have the answer. First off alittle backround about the program, I used the peak detector vi to find the max's and min's on a graph. I then used the property node to display the cursor at those peaks as I selected through the list. But I have noticed on the cursor display that the cursor is not on the right x corrdinate, but when I zoom in on the point, the cursor jumps to the the point that the peak detector found. I thought it may have something to do with the interpolation of the line b/t the points but i tried every option in the property menu. If you need to know anymore about the set up of the program, please ask me because it is bugging me so bad.

Thank you so much in advance!

[JDave]

I have one particular problem that does not make sense to me, but I was hoping one of you may have the answer. First off alittle backround about the program, I used the peak detector vi to find the max's and min's on a graph. I then used the property node to display the cursor at those peaks as I selected through the list. But I have noticed on the cursor display that the cursor is not on the right x corrdinate, but when I zoom in on the point, the cursor jumps to the the point that the peak detector found. I thought it may have something to do with the interpolation of the line b/t the points but i tried every option in the property menu. If you need to know anymore about the set up of the program, please ask me because it is bugging me so bad.

This seems improved from 7.1 behavior. The cursor would stay at the incorrect point even after zooming in. :thumbdown: It seems that the cursor positioning is limited by the pixel values available at the current zoom level.

Workaround - First zoom in, then set cursor, then zoom out. If the flashing is unacceptable, you should be able to Defer Panel Updates and avoid the flicker.

David

[crelf]

Hi everyone!

Welcome gammalight - it's always great to welcome new members. I hope that you get a lot out of the posts here, and we look forward to your chiming in with your 2cents as well

One suggestion: a lot of the people on this forum appreciate it when you post a code snippet or at least a screen shot of the block diagram to help us more quickly (and accurately ) understnad what you're going through and make suggestions.

I'm looking forward to you becomming and active member on the forum!

[gammalight]

This seems improved from 7.1 behavior. The cursor would stay at the incorrect point even after zooming in. :thumbdown: It seems that the cursor positioning is limited by the pixel values available at the current zoom level.

Workaround - First zoom in, then set cursor, then zoom out. If the flashing is unacceptable, you should be able to Defer Panel Updates and avoid the flicker.

David

Hey, I'll try zooming in first and setting the cursor, although it would be very convenient to not have to do that. Sometimes the cursor is quite far out of positon, I then use two cursors to scroll to two peaks and use the points to calculate a distance, so the two incorrect cursor positions compounds in error. I might try using the values right from the array of peaks. I would get a correct result, but it is just so much easier getting those values using the property node! I would post some code but I don't have it with me right now, I might try this later.

Could you guys refer me to a good book to learn labview better? I would like to learn to make nice GUI's, how to generate reports, make executables out of my vi's and do some data acquisition. I mean I want to become a pro labview developer, are there short mini session classes I can take?

Thanks everyone!

[Yair]

There are all kinds of LV books around (try Amazon). For some specific ones, you can try "A software engineering approach to LV" (old and hard to find), "essential GUI techniques", and "LabVIEW for everyone, third edition".

You can find A LOT of stuff in the NI site and in the Info LabVIEW mailing list. NI's site has a lot of articles and videos and the trick is to know how to find them.

[gammalight]

Over the weekend I read someone else's post that was having a very similar problem to mine, where the cursor did not display the correct x value on a plot. It was suggested that he try changing the "lock to plot" property on the cursor to the "free plot" property, I tried this as soon as I started working on my program and it worked very nicely. I can now calculate the proper depth's! Labview is neat if you can figure out its quirks.

[JDave]

Over the weekend I read someone else's post that was having a very similar problem to mine, where the cursor did not display the correct x value on a plot. It was suggested that he try changing the "lock to plot" property on the cursor to the "free plot" property, I tried this as soon as I started working on my program and it worked very nicely. I can now calculate the proper depth's! Labview is neat if you can figure out its quirks.

Very nice!! :thumbup:

Thanks for posting the solution. Much cleaner than my workaround.