Almost all vending machines with a payment function accept banknotes. These include not only snack and beverage machines, but also parking garage machines and, of course, slot machines. To ensure that only real money enters the respective machine, they have integrated bill validators.
As soon as the respective banknote is inserted into the slot, it is automatically checked by the software and then managed. The software recognizes what kind of bill it is and whether it is genuine. To this end, up to 20 features of the banknote that should indicate authenticity are checked in a matter of seconds. Among other things, the system checks what the paper is made of and how specific colors of light are absorbed. In addition, the bill validator at the vending machine identifies the security thread and the magnetic features of a banknote. Of course, the bill validator also recognizes the length, width and thickness of a banknote.
As soon as the check is complete, the credit is posted to the slot machine's account balance so that the deposited money can be played with directly. In the machine, the deposited banknote then ends up in the so-called money store or stacker. This is a housing with a press so that as many banknotes as possible fit inside.