Search this forum using the keyword: Barcode
There are several that discuss possible implementations in detail.
In short form, nearly any bar code scanner runs in "keyboard emulation mode" and this is the only real detail you need to verify. You simply launch filemaker, plase the cursor in a text field and scan a barcode. The text of barcode will appear in the field just as though you had typed it.
You can use scripting and OnKeystroke script triggers to automate the process. Most scanners allow you to program them to put a "preamble" of one or more characters at the beginning of the scanned text and a "postamble" of one or more characters (such as the enter key or tab) at the end of the scanned text and you can setup filemaker script triggers to respond to these.