Maybe you could clarify a few things for me, and we'll see how we can help ya. TCP/IP protocol occurs through an ethernet connection; RS-232 communication occurs through an RS-232 serial connection, typically through a cable that has a DB9 connector on both ends. Do you mean that the RF modems in question have the option to communicate via RS-232 and/or via TCP/IP ethernet? Specific information like the manufacturer of your RF modems, the model number of your RF modems, and how you connect the modems to the PC would enable us to give you more efficient support.
You can check our Instrument Driver Network (IDNet) to see if a plug-and-play/IVI driver already exists for your RF modem. (You'll need to know its manufacturer and model number.) In the case that you do find an IDNet driver for your modem, you can use this KnowledgeBase article for instructions on how to use the driver.
Another excellent resource to consider is the NI Example Finder. You can access this within LabVIEW by navigating to Help»Find Examples and then searching for serial or TCP/IP examples.