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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:

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:


Once you have selected an input device, you must select a decoder and the type of interface to the computer. Most batch systems use a periodic download over serial ports, and you don't have much choice in the interface method. Interactive systems have a choice of several interfaces.

When choosing the interface, you must keep the following factors in mind:

As with the input device, you should test the system architecture you choose in as many real-world conditions as possible. Interfaces come in these basic types:

Interactive Systems

When using serial scanners with PCs, keep in mind that your application needs to "monitor" the serial port for incoming data. Most applications do not do this, and so an additional piece of software, called a "software wedge," may be required.

RF Network: Portable bar code readers are generally connected to a system through a modem or a serial port and processed in batch mode. However, they can also be connected through a radio frequency system ($4,000+). With the right software, the portable can be made to have real-time access to a database on a networked computer.

Batch Systems

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Last modified: March 21, 2006