Bar-coding

Contents

Codes, Decoders, Future, Interfacing, Printing, Readers / scanners, RFID technology - update May 1999

Introduction

Libraries were one of the first industries to adopt barcoding. Primarily used in the public and academic sectors where the problems of fast turnover of items to impatient users loomed largest, bar-coding technologies were an ideal automatic identification technology for early system builders.  Nowadays bar-codes are cheap to print and the reading technologies are varied and reliable.  This basic technology review is designed to summarise the key points about bar-coding for those new to the technology. See the Directory pages for suppliers.

Codes

More correctly, the code that carries the information in the barcode is termed a Symbology. Examples are Code39, Plessey, Telepen, Codabar. The grocery codes UPC and EAN are examples from another industry - although the ISBN coding on new book jackets is a form of EAN - extended to cope with the occurrence of the “X” character in the check position.   Each symbology has disadvantages and advantages of readability, ease of printing and the range of information that can be encoded.  Bar-code symbologies are less critical than they were since the improvements in the readers mean that a modern scanner can read all codes simultaneously and discriminate between them so that misreads are a rarity - but not an impossibility.
If you are choosing a symbology to use in a new library then choose from the standard few that are used in the industry - see the sidebar on features of different codes.

Printing

Printing bar-codes can be achieved by a wide variety of PC packages on all the standard types of printer e.g. laser, ink jet and dot matrix. Special on demand labelers are also available.  Larger libraries generally find that the trouble of printing their own codes is just not worth it since there are many commercial printing service providers available who will print codes of guaranteed readability.  Smaller libraries can certainly print bar-codes successfully and many of the library management systems (LMS) provide an integrated barcode printing function as part of the acquisitions or cataloguing module.  When printing codes yourself, consider:

• size of labels and amount of data to be encoded - get some sample codes from the LMS or software package supplier and ensure that the book accession number fits the label. Make sure that there is sufficient white space at each end of the label beyond the code - this enables the reader/scanner to “synchronise” on the code.
• the label adhesive - you want the labels and the item to become firm friends - not brief acquaintances! Labels come in varying grades of permanence - ask for “permanent adhesive”.
• how to record sequences of numbers printed - when printing numbers in batches it is easy to reprint a sequence and find duplicate numbers affixed to items in circulation.  Although your software will generally help sort things out by refusing duplicate accession numbers to be added, once duplicates in the system they can cause havoc.

Suppliers of barcode printing requisites can be found in the Directory section.

Interfacing

Interfacing barcode readers is usually via the keyboard of the terminal/PC (known as a "wedge" connection) or via the serial port for older type systems where terminals are directly connected to the central computer or communications device. Make sure that you get the correct type of connector. You can also connect a barcode reader to the serial port of a PC and run software on the PC that interfaces with your application when the codes are read.  All of these schemes work and each have their advantages.  I prefer to use a keyboard "wedge" connected device since there is no additional software required and usually the power for the barcode device is drawn from the keyboard supply - makes things nice and easy. When ordering barcode readers, make sure you know exactly how you want to connect it, and the type of connectors you require e.g. PS/2 or DIN keyboard connectors.
 

Readers

The term reader covers all of the technologies designed to interpret bar-codes. There are 4 basic kinds of reader:

• Pen or wand - the original device seen in libraries nearly 30 years ago. Used by tracking across the code from end to end manually.  The cheapest device but can be prone to usability problems.  Target price - about £250
• CCD scanner - now virtually the same price as the pens.  Used by holding a visible scanning patch of light over the code. Easier to learn than a pen put be careful if you have long codes since the width of the scanner has to match the code length - use pens or lasers if a problem. Target price - about £400 - £450
• Laser scanners - normally more expensive than the ccd scanners but coming down in price - can be found below £300 from some suppliers but typically £450-upwards Laser scanners can be mounted on a stand for hands free operation and even in the desk like a supermarket checkout.
• Swipe readers - like the credit card readers in shops - they are simple to use for patron cards and can be connected to entry control systems and unstaffed issue terminals. With a decoder, the swipe or (slot scanner) will cost about £280-300.

Check out THE book on barcodes!

Glossary

Glossary of barcoding terms - from Inotec Ltd

I wonder why

The concept of Barcode keyboards never really took off?  Using barcodes as a means of controlling a computer has many advantages - you can get a customised layout of the main functions for your system e.g. Issue, Return, Renew etc. for virtually zero cost - just create the barcodes, laminate on paper and distribute to service points. 

There are real ergonomic advantages as well - if an assistant is wielding a pen or scanner with one hand and a book or card in the other, then there is a disruption to work flow when a key or two has to be pressed - or a mouse manipulated. With a paper keyboard, the scanner is quickly aimed at the code and the function accomplished with no need to juggle.  Simple and effective.

Decoders

The reading devices described above may or may not include a decoder. A decoder is the processor that actually turns the bars into characters. Mostly with CCDs and laser scanners, the decoder is built into the unit. With pens and swipe readers, the decoder is often a separate device that requires its own power source.