VI not updating DAQ readings correctly

Question

I am using a usb-6009 to acquire a DC voltage from a pressure transducer. My vi runs a loop that averages N data points of the voltage per loop and then displays the average on the front panel. When it cycles through the next loop, it then averages the next N data points and displays the result. Here's my problem: if I change the DC voltage to a new lower value, even after some time, the front panel continues to report voltages on the order of the original voltage. I would like the front panel to update an accurate voltage reading in real time (well, after every N points). I've been stuck on this issue for some time and getting to the end of my rope. I suppose it is probably a simple vi programming issue as I still am pretty new to LabVIEW.  My vi is attached.  Any help would be greatly appreciated.
Attachments:
Velocity Scan (x,y) 3.vi ‏191 KB

Answer 1

Hello fattyskaty!
Thanks for your post back.
I
think the best way would be to use some kind of sequential error line
handling to make each case execute sequentially. This way you will not
have a conflict when writing to local variables.  It looks like you
have alot of local variables that could be written to at different or
the same time. I see that you have about 10 case structures that are in
the same programing loop. With out timing your computer will execute
this as it so choses.Take a look at the attached picture, this is NOT
at all a best case programing practice but it shows how to use error
lines and multiple case structures. The best way is to figure out what
you need to happen and when. You can also run the error line through
the false case of the structures so that way every case is executed one
after another. Let me know if this helps you to get your program at up
and running for the time being.
Cheers!
Corby_B
http://www.ni.com/support 
Attachments:
error lines.jpg ‏54 KB