POS Software

So i been dabbling with my company’s equipment. Long ago they bought a pos system. They had the ticket printer, regster, scanner, and software. But before i joined them they lost it. A long time ago.

So okay my question is..what is the best POS software? I tried telenet which i didnt like (trial). And quickbooks pos 4.0. and now retailman. My problem is i can’t figure out how to make the computer recognize the cash register which is already connected to the printer