A while loop will run continuously as long as the continuation terminal's value is true (at least in 6.0) so all you have to do is enclose all of the code in your subVI with a while loop. Starting and running it is easy. You hve to decide on how you want to stop it. You can have a front panel Boolean to stop the while loop by operator intervention, wire the terminal to a global variable that is set by the main, or use VI Server in the main to set the value of a front panel Boolean in the subVI.
