Certainly it's possible. If you have debugged the instrument calls in your I/O Assistant, then you could convert that to a VI and modify it to accept variables that you pass from a higher level VI. In the converted I/O Assistant, you will find some VISA Writes and VISA Reads (assuming you created both types of steps in the I/O assistant). If you have a write step that does something like SET:AMP:2 and want the amplitude to be a variable, create a front panel numberic control, use that as an input to Format Into String with the string format of SET:AMP:%f and take the output of the function to your VISA Write, you've now got a VI that you can programtically set the amplitude.
Personally, I find it easier to just debug instrument I/O in MAX and write t
he driver from scratch instead of using the assistant. For information on this, I would suggest going here to check out the guidelines, instructions, and development tools. The Instrument Driver Network has thousands of examples that you can look at to give you an idea on how others have been written.
