Image Analysis Threshold won't work in program program freezes

Question

I am a new user to labview and I probably have an error in my code but the only problem is that there are no error messages I get from my code and it runs up to a point at which the program freezes and I can't click any buttons on the Front Panel. Basically everything works up to when I want to choose the Threshold of my image at this stage it creates an image of the values in the threshold buttons but I can't adjust the values anymore to find out the best values.
I should say that I have tried my Threshold code on its own and it seems to work fine so I am really confused as to what is getting muddled up!
Any help on what might be wrong would be helpful. I have added the VI and an image that I am analyzing.
The process currently goes as follows, you load the image, then choose a colour plane (usually green) that gets extracted. Then you draw a line on the border of the object and it rotates the image to make it straight and then you choose a ROI and it cuts the main object out. Finally at the point when you should be choosing a Threshold it hangs.
Thanks for any help!
Solved!
Go to Solution.
Attachments:
Image adjustment version 4a.vi ‏143 KB
Sample 2.jpg ‏2359 KB

Answer 1

Hi,
The root of your problem is in how you have used multiple event structures. Typically, a program should just have one event structure, which handles all events during the program. The vision functions were all working correctly!
From looking at what you are trying to do, I think it would be worth using a well known architecture called the state machine with events. I'll attach some code framework to show you what it might look like for you, you can adapt it to suit your program. I hope its enough for you to get an idea of what I'm trying to show you, it doesn't have any code in it yet, but I think it gets the idea across, and if you combine it with the link below on state machines, it may help you to set out your code in a better architecture.
A few links you may find helpful:
Event programming: http://www.ni.com/white-paper/3331/en
Caveats for using events: http://zone.ni.com/reference/en-XX/help/371361J-01/lvhowto/caveatsrecmndtnsevnts/
State machine: http://www.ni.com/white-paper/2926/en
let me know if you have any more questions.
Ian S
Applications Engineer CLD
National Instruments UK&Ireland
Attachments:
Event state machine example.vi ‏14 KB