The Components of a Bar-Code Tracking System
An inventory-tracking system based on bar codes has three basic parts:
- The bar-code label
- A suitable data-storage software program
- Bar-code readers
Anyone is capable of designing and purchasing a basic system. Designing more elaborate systems requires more knowledge of computers and bar-code systems. The following component information will help you assemble your own system or provide enough information so you can discuss your needs with a system designer.
You can purchase a supply of preprinted bar-code labels or generate your own using label supplies and a printer.
If you purchase preprinted bar-code labels, you must specify exactly what you need. Include the range of ID numbers to be encoded, the bar-code symbology that your software will understand, the label’s dimensions, the material it is to be printed on, and any information that belongs on the label besides the bar code.
Generating your own labels is easy and provides more flexibility, because labels can be made whenever you need them. You will need a printer, bar-code labeling software, and a supply of blank labels.
The readable lifetime of a label depends on the label material and its environment. Paper labels are the cheapest and most common, but they are not very durable.
Sometimes labels are printed on vinyl, polyolefin, polypropylene, or polyester. Polyester labels are considered the most durable. These synthetics resist heat, cold, smearing, humidity, abrasion, and chemicals better than paper labels. Consider using synthetic labels when they will be subjected to harsh conditions or when the surface of the item being bar coded is curved or flexible. Ensure that the label material is compatible with your printer.
If you do not buy preprinted labels, you will need labeling software and a printer. Because a bar code is a special type of character font based on graphics instead of letters, printing a bar-code label requires software that can translate data from numbers and letters into a bar-code symbology.
Printers designed to print bar-code labels (thermal printers) often contain bar-code fonts allowing you to print bar codes without software upgrades. When you want to print characters as a bar code, you encode the characters by including a special symbol that tells the printer that the text is to be bar coded. A macro (small program) can be created to automate the process. Check the manual or contact the printer vendor for information on your printer’s capabilities.
If you will be using a DOS- or text-based computer, such as the old Data General machines, consider purchasing a barcode printer module. The module plugs into the printer, and the printer cable from the computer plugs into the module. The module contains software that will make your printer work much like a thermal printer when you use the special character that activates the text to bar-code conversion.
Your inventory program may contain bar-code-labeling software modules, or you may be able to purchase labeling modules. Some modules are basic, but others are as powerful as standalone labeling software programs.
You can purchase a stand-alone program that allows you to create and print bar codes. Most labeling programs contain features like:
- Scalable text and bar-code fonts
- Support for most bar-code symbologies
- Ways to import image and data files
- Software interfaces for popular database programs
- Uncomplicated user interface
They allow you to easily create custom labels with lots of information such as the label shown in figure 1. This label includes bar-code identification numbers, text labels, a graphic, and health and flammability warnings. It can be printed in several sizes.
You can purchase a bar-code font or bar-code program to load into your computer. Bar-code fonts allow existing Macintosh or Windows programs, such as Word or WordPerfect, to convert text into a bar code and print labels. Bar-code fonts are an excellent choice if you want to print simple bar-code labels and your inventory system is based on a standard spreadsheet or database program, such as Excel, Lotus, or Access. Wordprocessing software and bar-code fonts allow you to create elaborate labels with little additional cost.
Figure 1—Labeling software allows you to create
custom labels to fit
almost any need.
Programmers can obtain bar-code DLL (direct link library) modules, allowing bar-code labels to be composed and printed from custom applications. This is a good option when creating systems inhouse. Many sample bar-code font and DLL programs are available for downloading from the Internet.
A bar-code-based inventory system requires a printer capable of printing bar codes or a supply of preprinted labels. Purchase a thermal printer or use a common dot matrix, inkjet, or laser printer.
Newer standard office printers (dot matrix, inkjet, and laser) can print bar codes if the correct software is installed. For an older printer, you may need to update the printer driver or purchase a bar-code printer module.
Dot matrix printers can produce low- and medium-density paper bar-code labels. They can print one label at a time, but can’t print on synthetic materials. Some scanners will have trouble reading a bar-code label printed with a dot matrix printer. Dot matrix printers are a good choice for low-cost operations with no need to use tough label materials. Change the ribbon often.
Laser printers work well as bar-code printers. They work with almost any type of labeling paper, have excellent resolution, and produce clear and long-lasting high-density bar codes. Laser printers can print on durable synthetic materials if the blank labels are made specifically for a laser printer.
Adhesive-backed labels for laser and inkjet printers are available on standard letter-size sheets. A sheet may contain any number of labels depending on their dimensions. A label sheet is fed through an inkjet or laser printer just like normal printer paper, but it must be fed with the correct side up.
Inkjet and laser printers work similarly for bar-code label printing. However, because most inkjet printer ink is water soluble, it is not suitable for use in wet or high-humidity areas. Do not use an inkjet printer if the label will be subjected to any kind of abuse. The interaction between inkjet printer ink and most synthetic labels creates a slippery mess that is highly sensitive to abrasion (figure 2). If you use an inkjet printer, be sure to use label stock made for inkjet printers. If labels need to be readable for several years, they should not be printed with an inkjet printer.
Figure 2—This label was created using an inkjet
printer
on
paper meant
for laser printers.
Light
rubbing
produced
the
smear, which
will
prevent
the bar
code from being read.
Thermal printers are used specifically for printing bar-code labels. They require specialized ribbons and label supplies. When you need only one label at a time, thermal printers are a good choice. There are two types of thermal printers: direct thermal and thermal transfer.
Thermal printers often contain text and bar-code fonts controlled by special codes directing the printer to print a bar code from alphanumeric characters. An experienced programmer can often add bar-code printing capabilities to other programs. You can purchase labeling software compatible with your thermal printer.
Direct thermal printers, sometimes called thermal autochrome printers, use heat-sensitive paper to create the image. The hot print head causes the paper to turn black, creating the desired image. Exposure to sunlight and heat will turn the label entirely black, making the label unreadable (figure 3). A direct thermal printer is not recommended except for indoor short-term applications.
Figure 3—These labels turned black after an hour
of exposure to direct
sunlight. A fresh label
(right) is shown for comparison.
Thermal transfer printers use heat to transfer ink from a ribbon to the label. They use a special ribbon with a wax, wax-resin mix, or a resin-based ink. Thermal transfer inks containing more resin are more expensive, but last longer. Polyester-based or other synthetic labels are required if you use high-resin ink. Thermal transfer printers provide more label stock options than other printers. Suppliers carry types and sizes for any imaginable application.
Data storage software is the heart of any inventory tracking program. You can purchase a software package or design your own system using a spreadsheet or database program.
Users with few reporting requirements or small inventories may be able to use a spreadsheet-based program. An “add-in” software package for your existing spreadsheet program may approach the power of a database.
Users with significant reporting requirements or large inventories of many different items may need a database. While databases generally take longer to set up, they provide immense data-handling capabilities and can generate reports easily. Microsoft Access and other database programs allow you to create your own inventory program (figure 4). To test the feasibility of constructing your own database, you may wish to experiment with your current software or with databases that are available for a free trial period. You may be able to use the template “wizards” in database programs. Wizards ask the designer questions about operation and data storage requirements, then automatically create a customized program, which can be modified.
Figure 4—A screen shot taken from a sample
database created
using Microsoft Access.
Finally, you can purchase a stand-alone inventory and tracking software program. These programs are recommended for those who do not want to create their own inventory systems or who have complex operations. Prices range from $200 to $5,000, depending on the features and the number of users and workstations. The simpler and more economical software programs don’t require extensive computer skills to set up. Some of the more powerful and expensive systems offer features for specialized operations such as managing chemical storage and checkout areas, tracking hazardous materials, and inventorying real property. Most of the programs are available for free trial periods so you can determine whether they meet your needs.
Reports provide a fast and easy way of accessing and sorting through a large amount of data. If you are fluent in structured query language (SQL), you can generate reports that will tell you almost anything you want to know about the stored data. Many standard bar-code-based programs offer built-in reports. Select the desired report from a menu and print it. Some programs offer reports tailored for specific regulation reporting requirements, such as the Emergency Planning and Community Right to Know Act (EPCRA).
Some of the more common built-in reports include:
- List by location—Lists materials at chosen locations
- List by ID number—Lists the quantity and location of items
by their identification number
- List by low limit—Lists items in stock quantities below their
designated minimum stocking quantity
- List by high limit—Lists items in stock quantities above their
designated maximum storage quantity
- Shelf life—Produces a list of items that have expired or will
soon expire
- List by material type—Lists items of each type and their
quantities
- List by person, work group—Lists name and quantity of
items each person or work group has used within a specified
time period
- List by chemical—Lists the amount used or quantity on
hand of each chemical
- Delinquent container—Lists containers that have not been
returned to storage
- Returned containers—Lists all returned containers grouped
by person, time, and/or chemical
- Incompatible material guide—Contains guidelines based on codes and laws showing which items cannot be stored together and any required spacing and barrier separations
If you design and program your own inventory and reporting system, include features that allow users to access the reports by selecting them from a menu. Deciding the types of reports to build is a basic step in the initial design phase and often guides decisions about the type of data that will be stored in the database.
