How Do Scanning Cash Registers Work?

A scanning cash register is one that combines a traditional cash register with a bar code scanner. This not only removes the need for a checkout operator to manually type in a price (for example, from a price label), but can make it easier to track stock levels. A scanning cash register may also be described as a complete point of sale system.

Scanning cash registers allow the operator to automatically retrieve the price and details of an item, adding it to the running total of a customer's shopping and in many cases feeding into a stock control system. The register can have either a handheld scanner (which the operator runs over the bar code) or a fixed scanner (over which the operator swipes the item). The scanner works by beaming light onto the item and measuring the reflection from different points of the bar code. Most bar codes use black and white to increase the contrast between the different points and reduce the possibility of a misreading.

Most scanning cash registers work with a system known as the Universal Product Code. This is a linear system, meaning the image is made up of vertical lines of different thicknesses, corresponding to digits. The bar code has the digits printed as numbers along the bottom in case there is a scanning problem and the operator needs to input the number manually.

UPC numbers are made up of 12 variable digits, along with three fixed vertical lines that indicate the start, middle and end of the bar code. Among the digits in each item's bar code are numbers indicating the manufacturer and specific item, which correspond to national and international product registers to avoid duplication or confusion. Some of the digits refer to other relevant factors, such as the weight of the item, a price reduction or a check digit that makes sure the bar code hasn't been misprinted.

Some stores, particularly grocery chains, now use self-service checkouts. These are scanning cash registers with a fixed rather than handheld scanner, which the shopper operates, thus theoretically reducing the number of staff required. Usually such devices require the shopper to pack scanned items in bags placed on a scale, with the device checking that the bags correspond to the weight of the scanned items, making it harder to sneak items out without scanning and paying for them. The self-service machines can cause frustration if items do not scan correctly or if a shopper must wait for a staff member to authorize the purchase of age-restricted goods like alcohol.