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We appreciate your patience as we improve our online experience.
05-23-2013 12:40 PM
Hello,
I am brand new to LabVIEW and need to get a small project done quickly. I have only really used Express VI's...
I do, however, have a DAQ and control system up and running (I'm sure it could be done much more efficiently, and I plan to refine as I learn)...
What I really need to know are two things:
1) How to ensure a pair of digital outputs are off on start-up (I have them default to off on power-up in DAQmx) but I mean on start-up of my VI.
2) How to ensure they're off on exit of the VI (no matter what the state of the toggle in the on screen, if they stop it, I need the outputs to go off).
Please can anyone give me some help, or an example?
-Jeff
05-23-2013 12:47 PM
You could just simply write falses to the digital lines at the very beginning of your program and again in your shutdown code.
05-23-2013 12:53 PM
It sounds like you really need some sort of state machine architecture. This way you can have certain tasks that happen on start up, shutdown and anywhere in between.
05-23-2013 12:57 PM
Cross,
Thank you, for the reply.
That's exactly what I'd do in language I was familiar with. I literally just don't understand the graphical syntax yet. The express VI's are all I've touched--even the loop and exit criteria were auto-generated by LabVIEW.
I just need to understand (may be an example), of DO control on start-up / shutdown...
-Jeff
05-23-2013 01:07 PM
Keen,
Thank you too, a state machine might really be the thing I need. Not sure how best to implement one in LV, but the concept is very familiar.
Even if I figure out the init, run and exit states (would add-in other states too, later, e-stop, limit, etc.) still not sure how the code can set a digital output. I'm that new to LabVIEW!
-Jeff
05-23-2013 01:32 PM
Might I recommend taking some tutorials:
And be sure to read up on the state machine:http://www.ni.com/white-paper/3024/en
05-23-2013 01:36 PM
I get that, but thank you.
I was hoping there was a "stick this control in here, set output state, link to stop button" kind of answer, or "here's an example of that with a DAQ Assistant!"
I appreciate the links.
05-23-2013 02:40 PM
Just because you have a great set of initials...
Here would be one way to do DO with set-up and exit
The Sub.vi is simply this
05-23-2013 02:47 PM
Jeff B,
They are strong initials, aren't they!?
Ok, I think I understand some of what's going on in there. I will study it and try to make some sense. Would you happen to have the actual .VI of that I can play with?
Thank you, Jeff, much appreciated!
-Jeff B.
05-23-2013 03:06 PM