Once you have decided on the scanner technology, you must design the system. These systems can be set up in several configurations. Some applications will work with only one particular system type, but most applications allow you to select the system to meet the best cost/performance requirements. The basic system types are:
Single User: These systems use a single PC with a single bar code reader to process data. These are generally the best type of system to start with, as they give you experience with bar code technology without some of the complexities of multi-user systems. An example of a site with a single-user system is a small video store that uses a wand to read bar codes on movies and stickers on customer cards. The store might also use a slot scanner for customer cards.
Multi-user: This was once the most common type of system. It consists of a single computer that is hooked to several bar code readers, terminals, or both. A multi-user operating system manages the data collection.
Local Area Network: These systems connect several essentially single-user systems and a common file server using a network. These are the most flexible systems and currently the most popular.
Portable Systems: Prices of portables have fallen over the last few years, making portables one of the best solutions for bar code applications. Portables are used with computers to keep data current either in real time or in batch mode.
A single-user system is simply a PC with a bar code scanner attached. The system generally uses a wedge to simulate keyboard input. A wedge can be used with any PC that has the same keyboard interface as the wedge. Most computers have either a DIN connector (like that on IBM computers through the AT) or a PS/2-style keyboard connector. A few companies make their own, nonstandard keyboard connectors. You must be sure to get the right kind of wedge for the computer you are using.
The normal action of a bar code reader is to simulate typing the keystrokes for the characters in the bar code and then press the Enter key. You can change the Enter key to a tab key or any other key for specific situations.
When the reader must be remote from the PC or terminal, you can later connect it reader to a serial port and use a "software wedge" to send the data into the keyboard buffer. Another possibility is to write the application so that it monitors the serial port for incoming data. Serial decoders are also useful if you must support a computer that uses a nonstandard keyboard interface And when you want to use a single bar code reader with a combination of PC, Macintosh, or UNIX systems. Software wedges are available for a variety of operating systems.
Multi-user systems have traditionally been the most common type of bar code system. This system uses serial ports to connect a single PC or other computer system to multiple bar code readers, terminals, or both. Each terminal runs a single session on the multi-user operating system. Cheaper PC prices and the availability of very basic network PCs will undoubtedly sway some users away from multi-user systems. Clearly the multi-user System is on its way out.
This type of system requires a multi-user operating system. If you want to use terminals with bar code readers attached to them, you can use any multi-user operating system, such as DR Multi-user DOS, VM-386, or UNIX.
Networks work just like several single-user systems connected together to share data. These work much like the multi-user systems shown above, except that each station is able to run any application. Networked PCs can run graphics-based and text-only applications and perform any other MS-DOS or Windows functions. The multi-user systems mentioned above will work with any text-based program.
Networks provide this flexibility at the expense of cost. Even an inexpensive network, such as Lantastic™ or Netware™ Lite, will cost several hundred dollars per station more than a similar multi-user system. A high-performance system, such as Netware, costs around $350 per station (with a network card) for a 10-user version. These systems also require a PC at each station.
You must also be careful of security with PCs. Most PCs have a floppy disk drive, which makes them susceptible to security violations. Multi-user systems are more difficult to exploit.
Portables are most often used in conjunction with a computer system for a bar code application. They can be used with a single-user, multi-user, or network system. Each portable has its own operating system and program. To collect item, location, and quantity data, you would need a custom program. At Data ID we sell programming tools that allow nonprogrammers to develop applications such as this.