Thank you for your post!
If you plan to use FileMaker Go, see Scanning a bar code.
Third-party scanners that work through a computer and FileMaker Pro will probably use some kind've trigger after scanning to either Find an Item or add said item to an invoice, etc. You might see Understanding and using Script Triggers.
I'm also going to move this thread from the FileMaker Community Feedback Space to the Discussions Space where others might find your post easier and offer further advice. I'm sure there are developers that have great suggestions on this process.
Almost all bar code scanners function in "keyboard emulation mode". You hook them up or pair them via blue tooth and your computer responds to the scanner as though it is a keyboard and scanning a barcode will enter data into the field just as though you typed it. Thus, you can click in a field, scan the barcode and run a script that finds or links to the data associated with that barcode. (The script can perform a find or you can have a relationship that matches on the bar code value.)
Once you can do that, you study the technical info that comes with the scanner. Most allow you to specify a "post amble" of text entered into the field in addition to the scanned bar code. Some also permit a "pre amble" of data inserted into the field before the scanned data. You can use both to trip script triggers:
If you can set up a pre-amble, you can set up the OnLayoutKeystroke trigger to run a script that checks for the text you specify as the "pre-amble". If detected, it uses go to object or go to field to put the cursor into the desired field to receive the scanned data and exits. If it does not detect the pre-amble it exits without doing anything so that you can enter normal keystrokes into any of the fields on your layout. What this does, is allow you to simply scan a tag with the bar code reader and FileMaker automatically detects that a scan has started and puts the focus where it is needed in order for a field to receive the scanned data.
You can then set the post amble to enter either tab, return, or enter--one of the three keystrokes that can be set up to exit a given field in FileMaker. You can then set up the OnObjectExit trigger on the scan field to perform any script that you need to use to process the scanned data. Note that with this set up,you can manually enter the data off the barcode tab and press that same key you specify as the post amble and your solution will behave just as though you scanned the data.