I'm a little confused on why the RF modem should make any difference at all in the system. My understanding is that any type of modem should be transparent to the overall data transfer. The modem should take care of all of it's transmission protocol and all you should have to worry about is the serial protocol. If you are not familiar with RS-232, the Serial Communication Overview tutorial should be able to help you out. I hope this answers your question, have a great day!
