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Weird Problem in LabVIEW with Vision


Hi All,


I have a problem with my LabVIEW program which runs with Vision. I'm sorry if I appear vague, I work for a government company and am limited by what I can disclose. I'm not really looking for specifics at this time, just any fundamentals that could be causing my problem.


Basically, in essence, my program has a constant video feed from a camera, and a device which is being switched via parallel port. When the parallel device is switched, the camera settings change (there are two sets of settings, if you see what I mean - one for when the parallel is On, another for when the parallel is Off).


The problem I'm having is, that when the parallel device is off, the image is fine. When the parallel device is turned on, the image feed becomes very grainy. I can see no logical reason for this - nothing is changing from the light source, and I've set both sets of settings to be identical.


Can anyone suggest what could be causing this?


Thanks very much,


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Without knowing more about the hardware, I would suggest putting breakpoints in the code where any camera settings could be changed.  Just to see if any of that code is unknowingly being executed when the switch happens.


Beyond that, I suppose noise feedback on your parallel port could effect something.  Might try viewing the video directly and activating your parallel port.  This would at least tell you if the problem was outside of LabVIEW.  


Good luck. 

Message Edited by pallen on 02-12-2010 01:38 PM
Patrick Allen:
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Argh the solution was so simple! All I had to do was remove the sub VI (something wrong with that), rebuild it and rewire. Removing the sub VI was fine, as was the rebuilding - I forgot to rewire one terminal to the tunnel - Incredibly annoying - I spent about 4 hours trawling through my ugly and massive code to try and find a problem, and it was a missing wire all along!!!

Thanks for the help anyway!
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