David,
you can set all serial port parameters with VISA Configure Serial Port (Instr).vi which is used in all serial port examples that ship with LabVIEW. Here is a screenshot of the blockdiagram of this vi:

As you can see, the parameters are set with a property node. You can also use a property node to read these parameters.
Please note: Please ask this type of question in the
Instrument Control forum and not in the Profibus forum. Chances are much better to get a quick answer for this type of questions there.
Best regards,
Jochen Klier
National Instruments
Message Edited by Jochen on 09-21-2007 10:16 AM