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How do I use Barcode Information once it's Decoded?

Once a barcode has been decoded the decoder will transmit the barcode information to some external device that will use the information. Most decoders use some type of serial data interface and transmit the barcode data as ASCII characters. The most common interfaces used are RS-232, RS-422 and RS-485. Another type of interface is the keyboard wedge. The following is a brief explanation of each.

RS-232 - This is a short distance serial interface. In general, two devices communicating with RS-232 should be within 50 feet of each other. RS-232 is a common interface most all computers and is present on all personal computers.
Here's a tutorial on the Fundamentals of RS-232 You must be able to handle .pdf files to get this one!

RS-422 - This is the long distance version of RS-232. Two devices communicating via RS-422 can be separated by as much as 4000 feet. Another difference that the user will notice is that each signal consists of two connections, usually labeled plus and minus rather than a single one. RS-422 can also be used in a polling configuration. This is where several units are connected to the same RS-422 port. Each unit is programmed to have an address. The single RS-422 port can then communicate with a number of barcode readers by polling each unit to see if it has any barcode data to send and then instructing it when to send the data.

RS-485 - RS-485 uses the same two wire communication scheme as RS-422 to achieve long distance communications. It is also used exclusively in polling mode. A number of RS-422 devices can communicate over a single twisted pair of wires. Again, each device has an address and is polled at certain intervals to find out if it has read a barcode and is ready to transmit its data. The advantage of polling mode is that a single computer port can be used to control and receive data from a number of different barcode readers.
A Tutorial on RS-422 and RS-485

Keyboard Wedge - This interface does not transmit data in ASCII format, but rather in the same data format as your PC keyboard. A scanner or decoder with a wedge interface physically connects between the keyboard and the PC. When barcodes are not being read, the keyboard operates normally. When a barcode is read, the data characters are sent to the keyboard port on the PC and look, to the PC, like they were typed on the keyboard. This is a good way to enter barcode data into an application without having special software to service the barcode scanner. Here's the Whole Story on the wedge interface.

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