Answers to Commonly Asked Questions on Bar Code Hardware

In this section we have tried to answer some of the most commonly asked questions about the hardware required for bar code systems

What do I need to read bar codes?

A bar bar code is basically a way for a computer to read numbers and letters. You will need a computer and a bar code scanner. You may need some software depending on the interface type of the bar code scanner although often there will be no additional software required (see How do I plug my scanner in?).

How do I plug my scanner in?

Bar code scanners come with several common interface types. The simplest and most widely used is the keyboard wedge interface. These scanners have a Y cable which allows the scanner to plug into the computer's keyboard line. To plug these scanners in you simply unplug your computer keyboard (make sure you computer is off first), plug the scanner in where to keyboard came out and plug the other side of the Y cable into the keyboard. Once you restart your computer the scanner can be used to scan bar codes straight away. When you scan a bar code the scanner simulates the keys being pressed on the keyboard and the scanned information appears on the screen wherever the cursor is, the same as if you typed the numbers in from the keyboard (only faster and with no mistakes). There is no additional software required with a keyboard wedge scanner and no additional drivers as the computer already knows how to get information from the keyboard. Also you usually don't need an extra power supply as the scanner can get enough power from the keyboard connector.

Another interface type is the serial interface (sometimes called RS232 interface). These scanners plug into the serial or communications (COM) port on the computer. These scanners require an external power supply as there is no power supplied through the computers COM port. Also the software you are using will need to be monitoring the COM port to check for data. These scanners are most commonly used for specific software that is designed to read the COM port to get bar code input.

The USB port has become standard issue on current computers and is replacing the COM port in many cases. Scanners are available to plug into the USB port also. These scanners require the right software to work much like a serial port scanner.

What type of scanner do I need?

Bar code scanners typically come in 3 main varieties: wand or pen style scanners, CCD (Charge Coupled Device) scanners and laser scanners.

The wand or pen style scanner is becoming less common and is hardly used now. These are the type of scanners you may have seen that are shaped like a pen and have a small light in the end. You read the bar code by moving the pen from one end of the bar code to the other. These scanners do not read as fast as the other kinds and hence are rarely used.

CCD scanners are probably the most widely used scanner currently as they offer good performance at a low cost. These scanners typically have a soft or diffuse light coming from the end opening. Traditionally these scanners had to be held almost touching the bar code to read, however CCD units are now available that scan from similar distances as laser scanners. CCD scanners offer very robust performance as they have no moving parts internally.

Laser scanners use a laser light to scan a bar code. These scanners can be recognized by the sharp beam of light emitted from the scanner. This beam is produced by shining the laser onto a rotating mirror. The main advantage with laser scanners is the reading distance. They can read over much greater distances than a CCD typically can. They have the advantage of being able to read from curved surfaces also. The laser can also be reflected into a more complex pattern allowing the scanner to read from multiple surfaces. This is the style of scanner typically used in shopping center check outs. Typically laser scanners are more expensive than CCD style scanners.

What is a bar code terminal?

You may have looked at the bar code terminal section on our products page or you may have seen bar code terminals or portable terminals referred to in other literature. A bar code terminal is simply a portable device with a bar code scanner built in. Typically a terminal also has a small screen, a key pad and on board memory. They may be used in applications such as stock taking or warehousing where data is collected away from a computer. The user can walk around and scan bar codes on items and add other information via the key pad. This information can then be loaded into the computer once all the information has been collected (this is called a batch terminal). Another type of bar code terminal is one with a radio transmitter built in (this is called an RF terminal). This device transmits the information back to a central computer as the bar codes are scanned. The section on sample bar code applications contains examples of systems using bar code terminals.

How do I print a bar code?

Bar codes can be printed on almost any type of printer, however there must be good contrast between the bars and spaces and the width of the bars and spaces must be accurate. As a result, sometimes a bar code printed by an inkjet printer onto a porous surface does not read due to the ink bleeding. The most common way to print bar codes is using a thermal label printer. These printers use a thermal process to either bond ink to the surface of the label (thermal transfer printing), or turn heat sensitive labels black (direct thermal printing).

Bar codes can be printed from special label printing software, that automatically calculates all the parameters of the bar code and shows it on the screen ready for printing, or using a bar code font, that tells the printer to print a bar code instead of normal numbers or letters. With some fonts you need to know a little about how the bar code is constructed in order to put in the correct start and stop characters or check digits. The

The products section has information on the printers and software required to print bar codes. Existco also offers a label printing service if you do not wish to set up for bar code printing yourself.

What labels should I use?

The choice of labels for your application will depend on the requirements of the labels. If you need to bar code an item that will sit on a shelf and be scanned once at the point of sale, a paper label would be sufficient. If you need to label an asset that will be scanned over a period of years, you may need to look at a plastic label that has been printed using a thermal printer. The application really dictates the label requirements. Labels can be paper, plastic or even metal. They can be printed using a sheet of labels in a laser printer, using a thermal label printer or even be industrially etched. Existco offers a complete range of labeling solutions for a full range of situations and environments.

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

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