As with the input device, you should test the system architecture you choose in as many real-world conditions as possible. The bar code reader connects between your keyboard and your computer and simulates keyboard input. The application program does not know the difference, and the user can always type in the numbers if the bar code is unreadable. This is the best choice in many cases. In this case the reader is connected to the computer or terminal over a serial port to the computer.
Serial readers are ideal for terminals, since most terminals are serial devices themselves.
Portable bar code readers are generally connected to a system through a modem or a serial port and processed in batch mode. With the right software, the portable can be made to have real-time access to a database on a networked computer. An application in the portable allows the user to collect the data. After the data has been collected, the user connects the portable to a computer through the computer's serial port and uploads the data. The data then resides on the computer in the form of a text file.