How Do Barcode Scanners Really Work?

You have probably seen scanners at work “reading” barcodes. We know some form of intelligent understanding takes place as a flashing red light passes over a barcode. But what is really going on?

The purpose of a barcode scanner is to scan (read) a barcode symbol and then provide an electrical output to a computer via a decoder and cable. The decoder recognizes the type of barcode symbology it is seeing, translates the bar and space content and transmits data to a computer in a human-readable format.

Twenty-plus years ago, you might have had a barcode scanner that could only read two or three types of barcodes. If you wanted to read a special barcode you would have had to go out and find another type of scanner. Fortunately, as technology improved and more and more barcodes were created, scanners also developed to read a wider variety of barcodes in both one and two-dimensional formats and then “auto-discriminate” (in other words, automatically determine) the symbology it is reading and then properly interpret the content.

Most often, the decoder is built right into the handle of the scanner. If not, then there are a few other ways to decode and transmit barcodes:

A keyboard wedge is put between the scanner and the computer. The scanner is called a cabled or fixed mount scanner because it relies on being directly connected via a synapse cable to a keyboard and computer. When a barcode is scanned, the information is immediately transmitted to the computer, almost as if the information was being typed onto the keyboard.

Graphic of barcode scanner plugged into a computer and a keyboard

Another type of fixed scanner transmits data via a RS-232 Serial port on the computer. In this case, the serial scanner transmits a barcode in an ASCII file format and much like a wedge, it comes out looking like keyed data. Both types of cabled scanners come with hand-held or hands-free options.

Graphic of barcode scanner plugged into a computer

• For more mobility, portable batch scanners aka “portable data terminals” (PDTs) were developed. They store data to be sent to a computer sometime in the future. This kind of device reads the barcode and you can see the information on a LCD display. Then you can type in additional data such as inventory count via a small keypad. PDTs require a “cradle” to rest the scanner and upload both the scanned and typed in data to the computer.

Graphic of a Wireless Terminal Scanner

• For mobility AND faster data retrieval, wireless portable scanners use a centrally located terminal such as a cradle to instantly transmit data to the computer when barcodes are scanned. 

Graphic of a Wireless Scanner
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