If you search this forum for threads on "bar code scanners" and Magnetic Strip scanners, you'll find several discussions that apply. Scanners, (bar code, Mag stripe and presumably RF ) input data into the computer using "keyboard emulation mode" which means the computer receives the data as though an extremely fast typist simply typed in the data from the card.
Thus, setting up fileMaker to work with such scanners is basicaly a process of first putting the cursor in the correct field and then running a script after the scan to process this data in whatever means are needed to do what you need. Almost all of these scanners can be configured to put text at the beginning and end of the scanned data. In FileMaker, you can then set up an OnKeystroke script trigger to put the cursor in the desired scan field. You can then append either tab, return or enter characters to the end of the scan to trigger a field exit so an OnObjectExit trigger can start up a script to process the scanned data. (With FileMaker 10, & 11, you can also use Install On Timer to start up this second script 1 second after the card is swiped and this can work better with some scanners.)