The pin definitions of the RS-232 interface would be documented in the manual. The pins are fairly standardized with typically a DB9 or DB25 connector and the instrument is either a DTE or DCE. For general concepts of RS232, see this and the NI tutorial. There are a couple of examples that come with LabVIEW that show some of the ways you can communicate to an RS-232 instrument and numerous instrument drivers that use serial communication. There does not appear to be an existing instrument driver for what you have so you will have to write the program yourself using the information in the manual. I would suggest you do your initial debug with a terminal emulation program such as Hyperterminal, Procomm, Putty, etc. until you are sure that you have all of the com settings (baud rate, partity, etc.) correct and are using the correct type of serial cable (there are two major variations).
