Answers to Commonly Asked Questions on Bar Codes

In this section we have tried to answer some of the most commonly asked questions about bar codes.

What is a Bar Code?

A bar code is a row of contrasting lines, or bars and spaces, that encode certain information to enable a computer to read that information quickly and accurately. The thickness of the lines and spaces determine what information is in the code. The bars can run horizontally or vertically and are usually scanned by passing a light across the bars. The information that can be encoded may be numeric, alpha-numeric or the full 128 character ASCII character set (the same one used on computers). This depends on the symbology, or type of code, chosen. (see What is a symbology?)

What information is in a bar code?

That's up to you. There are certain limitations if you are using standard codes (see Which symbology can I use? below). Most bar codes have a row of numbers or letters underneath, this is called the human readable component. It is purely the information contained in the code so you can read it in case the code gets damaged and will not scan.  Bar codes don't contain databases.  When a code is scanned the computer reads the number and then looks up the information from a database. The information contained in a bar code is usually the numbers you can read underneath.

How accurate is a bar code?

Very accurate! Bar codes have check characters at the end.  When they are scanned the scanner calculates what the check character should be and if it doesn't match, it gives a no read.   With bar codes you get the right information or no information.   If a price is wrong in the supermarket don't blame the bar code, it's the data held in the computer that is wrong.

Why should I bar code?

Bar codes are an extremely accurate way of referencing information and automating processes. There are many other ways to automatically identify an item but bar codes are still the cheapest and most widely used method. If you have any application that uses repetitive gathering of information, the accuracy and speed of the operation can be greatly improved by using bar codes. Also, every body is using them. This may mean you have to in order to comply with either supplier or user standards. If you aren't using bar codes now, chances are you will have to in the future. Existco can help you asses an application where you may be able to use bar coding. We can offer suggestions on how to improve the accuracy and speed of your operation and how to comply with required standards.

What can I use a bar code for?

The options are limitless. Basically any operation that requires the collection of data can be improved in speed or accuracy by the use of bar codes. If you think you can use a bar code but are not sure how, contact us. Typical applications include: Asset tracking, product tracing, stores control, security, time and attendance control, ingredient control, production flow control, stock taking, just to name a few.

What is a Symbology?

There are several different code types or symbologies available. A symbology is just one particular way to create a bar code. An example of a symbology is the EAN-13 symbology, which is the code used to identify retail items at the check out. Other widely used symbologies are code 128, UPC, code 39 and interleaved 2 of 5 to name a few.

Which Symbology can I use?

This will depend on your application.  If you are producing for a retail outlet you will need to use an EAN code.  EAN stands for European Article Number and these numbers need to be assigned so that you don't use the same code as someone else (see below).  If you are using codes to track items within your own organization, you can choose a variety of codes depending on your application.  For example Code 128 can encode the full ASCII character set and can be used to encode all sorts of information or Interleaved 2 of 5 can be used to encode just numeric data.  Please contact us if you need more information on your application.

How do I get an EAN number?

You apply for one through your local EAN authority.  For Australians this is EAN Australia.  They will issue you with a range of numbers which you can then assign to the different products you produce or supply. You can contact us for more information or EAN directly.

Why wont my bar code read?

With bar codes you get the right information or no information.  Bar codes will not read if the information is corrupted or if the bar code has been damaged in some way. There can be many reasons why a bar code will not read. It may have been folded or stretched, it may not have sufficient quiet zones at either end, it may have been smudged or have dirt on it. If you are printing your own bar code a bar or space is missing, the bars or spaces may be too fat or too thin (could be too dense or stretched so that the bar/space ratio is wrong), there may not be enough contrast between the bars and spaces (could be the wrong colored background or a faded label), the check digit is wrong (this is usually calculated by printing software so you don't need to worry unless you use true type fonts).

What is a "quiet zone"?

For a bar code to read correctly there must be some clear space at either end of the bars. This is referred to as a "quiet zone". This blank area allows the scanner to accurately determine the first and last bars in the bar code. Typically the quiet zone should be at least 10 times the width of the narrowest bar in the bar code.

Need more information? We can help you with all your questions in the area of bar coding. Just send us an information request or contact us via phone or fax

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