Q: Why do "virtual channels" mysteriously disappear?

[Jon Juhlin]

I am a newbie to Labview 6i and have been encountering a recurring problem.
I have been using the sample VI "Getting Started Analog Input.VI" as a
sample to practice basic techniques by making incremental changes and
observing the results. The first subVI in this block diagram is AI Config.VI
which requires an input "I/O" which tells it which channel to use.

Supposedly, I can simply enter a list such as 0,1,2,3 etc and have this
interpreted as aich0, aich1... of the specified device, but the only way I
have found to get the program to work is to create a "virtual channel" in
Measurement And Automation Explorer. If I do this, I can get then choose the
virtual channel and VI will run.

The problem that I cannot figure
out is that every now and then, all the
virtual channel information is deleted and must be recreated. I can't see
what it is I am doing that causes this to happen, maybe I'm clicking when I
should double click or something, but it sure is frustrating. I was just
running it a minute ago and they were there at the beginning of the session
and at some point just disappeared without ever acutally running a VI.

Any ideas would be greatly appreciated.

Jon Juhlin
j_juhlin@efn.org

[aderogba]

Do you have any device (hardware) connected to your system?

[Filipe A.]

Jon;

If you right click at the channel control and select the option named "allow undefined names", you will be able to type in the channel number as well as select the virtual channel.
Hope this helps.
To avoid the virtual channel to be deleted you can choose the option to save the configuration file in MAX. That will save all your channels to one file and everytime you open MAX, or try to access the virtual channels in Labview, the ones you created will be there.
Hope this helps.
Filipe