Currently there is not an instrument driver for the SR830 in LabWindows/CVI. However there is an instrument driver for LabVIEW. If you are interested in a driver for LabWindows/CVI you can submit a request at
http://ni.com/idnetIn LabWindows/CVI you can go to Help, Find Examples and search for serial to find examples on how to communicate over serial, and possibly write your own driver.
Shawn B.
National Instruments