If I understand correctly this is the scenario that you're looking at. The user presses the vi1 button and vi1 begins running. This vi continues operating until the Stop button is pressed in vi1. You want the user to be able to press the vi2 button and have vi2 begin running also.
One possible solution is to use notifiers in your event structure instead of putting the vis there. You can then put the vis in parallel loops triggered by the notifier. I have attached a quick example to show how this would work. This approach allows each of the vis to be started and stopped as many times as you like in any order.
I would also recommend that you use a reference to the Stop button on the main vi to allow you to stop the subvis.
Message Edited by John Rich on 06-10-2005 11:59 AM