Does anyone know how to operate this Scan and Go device (AFMIS)?

Not sure if you have an answer yet. The answer to your 21 versus 22 problem is that you will have to manually change what it uploads into AFMIS. Also, you should go up your chain of command, probably up to your RSC, and talk to your Food Service Program Manager. He or she can likely give you all the details you are looking for, especially about how to use it.

For those who are new to Food Service, like me, I'd like to share more info. Tonight (28 Mar 17), I spoke to our Food Service Program Manager about this unit. Here's what he told me. The Scan-and-Go scans ID cards and essentially replaces tracking of food consumption AT THE UNIT LEVEL. The scanner does NOT keep personal information, just a count, which is how you can double-scan. It does NOT replace head-count sheets at a DFAC, if you use one. In fact, it is sort of a double-counting device. You track your use at the unit level, and that feeds (pardon the pun) USARC and the various Regional Support Commands. All this is to help them estimate funding requirements for the next FY. On the other hand, the headcount sheets at your local DFAC track actual usage for their actual bill-paying. Anyway, the point is that at the unit, you either keep DA3230s or you scan ID cards. Either way, you input results into AFMIS. Using 3230s means you do manual input. Using the scanner, it's automated. If you issue MREs, go out to eat (mission requirements take you away from the DFAC you normally use), or if you routinely use a restaurant, you'll use this instead of headcount sheets. Your RSC *may* have policies requiring use of a scanner. Mine does. Can't get around it. Not sure if I like it or not, but as I'm new to Food Service, I may decide after I use it that I actually like it better than, "What's your last 4?"

there used to be an outfit called Versatile Mobile Systems in Seattle WA that handled & refurbished all kinds of hand-held scanners. The might be defunct (still) but i heard they were back in action.