Types of Scanner Interfaces
Home > Barcode Basics > Scanner Interfaces

Links to information on this page: Keyboard Wedge, Serial Port, Short-range RF, Portable Batch, RF wireless system

Keyboard Wedge

The scanner plugs in between the keyboard and the computer using a Y cable or similar connection. Data from the barcode appears at the computer's keyboard port just as though it had been typed manually. This is an excellent type of interface for use with existing programs, since no software modifications are needed.

Scanners are also available with USB keyboard wedge interfaces. The scanner physically connects to a USB port, but is automatically recognized by the system as a keyboard wedge device. Barcode data appears on the screen as though it had been typed at the keyboard. Advantages of the USB interface include simpler cabling and the ability to work with a wide variety of systems.

 

Serial Port/USB

The data from the scanner is transmitted to a serial port on the computer. Software must explicitly receive the scanner data via the serial port, so programs must be designed or modified to work with scanners. Since the scanner data follows a separate path from keyboard data, the software can directly control when and what sort of data will be accepted from each source; this can be good for on-line production systems where error checking is critical.

 

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

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 application

 

RF wireless system

This type of scanner employs a private digital cellular 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.