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Barcode Education » Reading Bar Codes

Once you have a bar code in hand, you must read it and process the information. Reading bar codes requires three basic decisions. You must decide on the input device, the decoder, and the interface. The input device reads the bar code and transmits the data to the decoder, which converts the data to ASCII characters. The interface is the connection between the decoder and the computer.

Input Devices

Input devices (wands, CCDs, badge scanners, and lasers) are the direct contact between the user and the bar code. No other choice you make will have a greater impact on the usability of the system. Naturally, there are several choices, in a range of prices. In general, you will get better service from more expensive devices, but this is not automatically so. The choice of input device is controlled by these factors:

Volume: Some input devices are inherently more usable and reliable than others. If you have a low-volume application, any input device will probably work well for you. A high-volume operation will generally be better off with a high-grade input device. High-grade input devices are fast and reliable.

Bar Code Quality: One of the advantages of high-grade input devices is their ability to read low- quality bar codes. In applications where bar codes are of poor quality to start with or are likely to be damaged, use of high-quality input devices can save time and reduce errors.

To select an input device, you must take all of these factors into consideration. Once you have made a tentative decision, you should test the system in as many real-world conditions as you can simulate.

Get the input device a little dirty, damage the bar codes, print them with a slightly worn ribbon or cartridge, test it with an untrained employee, and try to anticipate other problems that may happen during normal operation. This way you can make sure you have made the right choice. The most common input devices are:

Wands
: These are the most inexpensive input devices available ($140 to $180). They work well for low-volume scanning but have some disadvantages. They require a relatively flat surface, a fairly high quality bar code, and some skill on the part of the person operating it. However, in applications where someone must scan one bar code on a sheet full of bar codes, these are a good choice.

CCD (Charge-Coupled Device) Readers
: These are the next step up from wands ($400 to $600). A CCD has a read head the same width as the bar code (2 to 4 inches). The user sets the head of the reader on the bar code, and a series of LEDs scan the bar code and read it. This requires less skill than the wand, and it will work with most low-quality bar codes. They still require a relatively flat surface, and the CCD must be within 1/4" (.5 cm) of the bar code to read it. The surface can be slightly curved in the direction of the bars, but no more than about the curve of a 1-liter bottle.

Laser Scanners
: These are the best type of input device and are therefore the most expensive ($400 to $l,300). They will work with curved or uneven surfaces and will read most very low quality bar codes. They will also read over a much greater distance than wands or CCDs, usually 5" to 27" (I2 to 65 cm). Laser scanners come in general-purpose and heavy-duty versions.

Fixed-Mount Laser Scanners
: These systems use laser readers that are fixed in place, and the bar codes are brought to the scanners. The most common example is the scanners in used in grocery stores. Another example is a conveyor controller that reads the labels on boxes or packages as they move down a line. These are used in the airline industry to process baggage, in warehousing to control conveyors or other devices, and in many types of manufacturing.

Slot Scanners
: Slot scanners are used for time-and-attendance, security, and other systems. Each scanner has a slot that you slide bar-coded cards through. These scanners look much like the credit card readers you see in retail settings, but they read bar codes instead of magnetic coding.

Combination Scanners
: You can frequently mix two different types of input devices. For example, you can attach a slot scanner and a laser scanner to a decoder to allow users to enter information either way. Percon's PowerWedge 20 dual model is such a device. Many models allow you to attach magnetic card scanners to bar code readers. This way, you could process credit or ATM cards with the same system that reads bar codes on packages.
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