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Decoding of barcode scanners and interfaces

Upload the data connection with the host or interfaces, each have two distinct layers: a physical layer (hardware), the other is the logical layer, refers to the communication protocol. Common interface methods are: keyboard port, serial port or direct connection. When using the keyboard interface mode, the reader of the bar code symbol outgoing data is considered to be terminal or PC data issued by the keyboard itself, while they are also able to play all the keyboard functions. When using the keyboard port connection is too slow, or other interface mode is not available, we will adopt the way serial connection. Here direct connection has two meanings, a pointing reader does not require external decoding device directly to the master output, another means to directly connect to the host decoded data does not pass through the keyboard. Some commonly used terms dual interface (Dual Interface): refers to the reader can be directly connected to two different devices, and automatically configure each communication terminal, for example: a CCD daytime IBM POS terminal for connection, and at night it will connect a portable data terminal for merchandise inventory, use the built-in dual-interface functions, conversion between the two devices will become very easy. Flash memory (Flash Memory): Flash memory is a chip need the power supply will be able to save the data, it can be done in an instant rewrite data. Welch Allyn company's products use flash memory instead of the original PROMs, the product has a stronger ability to upgrade. HHLC (Hand Held Laser Compatible): Some terminal without decoding device can use an external decoder This is a way of communication, such communication protocols, commonly known as laser emulation for connecting CCD or laser reader and outside set decoder. RS-232 (Recommended Standard 232): computer and barcode reader, Modem, mouse and other peripherals serial transmission a TIA / EIA standards, RS-232 typically uses a 25-pin male DB-25 or 9-pin connector DB- 9, RS-232 communication distance is generally less than 15.24m, if a good cable, communication distance can be lengthened.