What is the principle of supermarket access control?

Working principle of supermarket access control The main function of the usual access control system in the supermarket is to prevent things from being taken out. The working principle is that every commodity in the supermarket has a bar code on its packaging bag. If there is no bar code, the supermarket staff will also put a dot label on it, and some bulk commodities (candy, vegetables, snacks) will also be labeled with bar codes after weighing, with information such as price on them. When checking out, the cashier will scan the barcode and register the barcode information at this time. There is an inductive entrance guard at the entrance of the supermarket. When passing through the entrance guard, the entrance guard will detect the bar code information of the passing items to determine whether the bill has been settled. If the cashier is not scanned, it will call the police when it passes.