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Types of Scanner Interfaces

Keyboard Wedge

The old way of doing this was to physically plug the scanner in between the keyboard and the computer using a Y cable or similar connection (pictured). Data from the barcode appears at the computer's keyboard port just as though it had been typed manually. No software modifications are needed; the only downside is that the software can't distinguish between scans and manual entry.

Now USB is commonly used to connect a scanner, and the type of logical connection can be set in the scanner's configuration. Virtually all scanners support keyboard wedge interface mode. A single USB cable is much simpler than the old Y cable.

Short-Range RF

short range RF Also known as cordless scanners, these devices include a radio-frequency base station that generally connects to the computer as a keyboard wedge. The scanner normally rests on the base station, which also acts as a battery charger. To scan, the operator picks up the scanner and reads the barcode; the data is transmitted back to the base station and from there to the computer. The data arriving at the computer appears to have been typed at the keyboard. Practical working distances from the scanner to the base station depend on the particular model, and generally fall in the range of 10 to 50 feet. These scanners are excellent for working in a limited area around a computer workstation, but where a connecting cable would be inconvenient. Working at too long a range can be impractical because all of the visual feedback to the operator appears on the computer screen; there is no means for the computer to send data or alert signals back to the scanner.

Portable Batch

batch scanners This type of scanner often has a keyboard and display and can be programmed to guide the operator through various menus and prompt for entry of information. Some small units may sacrifice the keyboard, display, or programmability in favor of compactness (one such unit is actually a ball point pen with a wand scanner built into the cap). Data is stored in battery-backed memory; the scanner can be connected to a host computer through a docking station or communications cable and the data transferred to the host. The data is normally transferred in a comma-delimited text file format, which can be easily imported into most databases, spreadsheets, and applications.

RF Wireless System

rf wireless This type of scanner employs a private digital cellular network or WiFi network. A central server computer attached to one or more radio-frequency nodes (transcievers); the number of nodes required depends on the size of the facility and the RF absorption characteristics of the building and its contents. One or more portable RF scanners communicate with the server continuously.

These scanners generally include a keyboard and display so that the operator can send a variety of data to the computer and receive responses. Interaction with the operator can be done through special application software running on the portable terminal, or the terminal can run terminal emulation software so that the operator is in effect carrying an on-line computer workstation that can interact with the host system just like any other workstation.