Bar Codes - An Overview

CAPITAL Visual Builder supports more than 20 of the most popular bar code types or "symbologies" plus variations. This section provides a general overview of their application. Bar codes can be printed on invoices, stock labels, purchase orders, picking lists, delivery dockets and other documents. Any information you wish can be printed as a bar code, although the most commonly coded items include such things as product codes and customer codes. Several issues should be considered before selecting a bar code symbology.

Does your industry have an accepted standard?

If the industry you are in has an agreed bar code format that it uses, this will probably decide which one you will select for use. Your customer may specify, for example, that "JAN-8" or "UPC-A" is the required bar code. In this case, the choice is made for you. If you do not have to conform to a particular format then you should select a bar code that prints as small as possible for a given number of characters. It must also support encoding of the characters you need bar coded. Certain bar code types take up more space (have a greater number of bars) for a given number of characters. The smallest bar codes tend to be able to encode less. For example, the bar code type "UPC-A" produces fairly small bar codes, but this topology is only able to encode numbers.

The bar code type "Code 39" can encode numbers, characters, and some punctuation. Compared to other types of bar codes it requires a lot of bars. This can present problems if the bar code labels or the spaces for bar codes reserved on your documents is limited. The bar code type "Code 93" produces a smaller bar code for the same number of characters to encode. Since both bar codes can encode letters and numbers, it is usually possible for you to code your stock based on your existing product codes, rather than have the computer assign a special, separate, numeric code for that purpose.

Do the products you handle already come bar coded?

If the products you stock already have bar codes on them you usually don't have to worry about printing your own bar codes. If not all the products you handle come with bar codes or you have no control over the product codes assigned to the goods you deal with, then a flexible symbology that can encode letters, numbers and punctuation is usually preferred. For example, if you select a bar code symbology that can only encode numbers and then discover that your product codes include letters of the alphabet, you will have to change your bar code. For example, if your product items have product codes like "123455" and "931121" try to determine if other products might have codes such as "123455B" or "12345-2". The letter "B" requires support for letters of the alphabet. The dash (-) symbol would require a bar code that enabled the encoding of at least some punctuation characters such as a dash.

Which bar code symbology is "best" ?

The basic rule of thumb is that the smallest bar code that does the job is the best. The more characters that a bar code symbology must encode, the larger the bar code will be. For example, bar code symbologies that can only encode the numbers 0-9 will produce smaller sized bar codes than a symbology that also handles letters of the alphabet. Even larger bar codes would be required for topologies that handled punctuation symbols and could differentiate between upper and lower case letters of the alphabet.

A further issue is whether the bar code scanning equipment you use can handle the bar codes you will be printing. There is little point in using a complex bar code symbology that also happens to produce relatively small bar codes, if your scanning equipment is incapable of handling that format.

Are special bar code printers required?

Any printer that has a Windows print driver and can print graphics (virtually all, these days) can support bar code printing using CAPITAL Visual Builder. If you intend to print labels then a printer that has support for tractor feed labels is recommended. Laser printers have excellent graphics capabilities and can quickly and easily print bar codes. However, because these types of printers are sheet based, they can be very wasteful of paper or label resources, especially if you only require the printing of a few labels at a time. Laser printers are best used when you are printing large volumes of bar codes all the time, or when you simply want to include bar code data on standard forms such as invoices and delivery dockets. Besides laser printers, many inkjet/bubblejet type printers suffer from the same limitations.

Dot-matrix printers usually make excellent bar code printers. Their main advantages include low running costs and their ability to use low cost tractor fed paper. Printing a single bar code label, for example, is not wasteful if you use tractor fed label sheets. However, 24-pin dot-matrix printers are definitely recommended. If you intend to use an older 9-pin dot-matrix then you should carefully test the labels or documents printed to ensure that your scanner or reading device is capable of interpreting the bar code without difficulty. You may not be able to print a very small bar code with a complex symbology on an old 9-pin dot-matrix printer. You may be forced to use a less complex bar code symbology, increase the dimensions of the bar code, or upgrade your printing equipment.

Are there special rules for printing bar codes?

If you will be printing bar codes on products that will then be scanned by other companies it is important to be conservative. Firstly, determine what guidelines are available for the size, placement and text information that must be included with the bar codes that you produce. Some scanners have difficulty reading bar codes that are not printed on a white surface. Where possible it is always a good idea to avoid coloured backgrounds. The bars themselves should be printed in black for maximum contrast.