How do you force DAQmx output to 0 at the end of program execution?

Question

I am using a 6713 to generate an arbitrary analog waveform on its output. However, once the labview vi has finished execution, the output voltage from the 6713 does not go back to 0 V. I have tried to force it back to 0 V by appending a 0 V amplitude waveform to the end of the analog waveform to mixed results (if I give it thousands of points, it goes to 0, but if I make it a more reasonable 100 points, it doesn't). How can I force the output back to 0 V. I tried stopping the task, clearing it, and stopping it and then clearing it. None of those worked.
Any help would be greatly appreciated.
Attachments:
6713 Interface.vi ‏144 KB

Answer 1

First, I have to ask, did you write this VI?
It is very hard to follow and has a lot of confusing structures in it.  IN the middle area where a lot of the DAQmx functions are, the error wire loops around so much it is hard to tell what is happening in what order.  To the lower left, an array is converted to a cluster, the cluster is unbundled, the individual elements are fed to a compound addition to get a single value.  Why not just use a sum array function on the original array?
The stop button is fed to the Stop Sign function.  This is Abort execution which is the same as hitting the red stop button at the top of the VI.  It ends the execution of the VI right then and there and doesn't allow anything else to happen.  Read the context help for that function.  As someone else has said on the forum,  "Using the Abort button is like using a tree to stop your car.  It will stop it, but there might be consequences."
How is this VI being run?  Is the Run Continuous button being used?  My guess is yes because I don't see any While loops and the only thing the stop button does is end the program abruptly.
You will need to rethink your whole architecture.  Stuff that needs to happen once should be set up before a while loop that has wires leading to the while loop or uses a flat sequence to make sure that it happens first.  This is you program initialization.
Everything that happens repeatedly would be in the while loop.  The front panel Stop button is what ends this loop.
Anything that has to happen before the program ends like closing out tasks happens after the while loop (either by wires for dataflow or in 3rd frame of a flat sequence structure.  With this, you should be able to reset your tasks so they output a zero voltage from the analog outputs before the tasks are closed and the program ends naturally.
Appending a zero to the end of the waveform won't help because if the waveforms run continuously, it will restart back at the beginning.
I would highly recommend looking at the example VI's for DAQmx functions and taking the tutorials for Labview that are available on the NI website.
Message Edited by Ravens Fan on 02-23-2008 10:45 PM