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Serial Ports

Serial Ports

An asynchronous port on the computer used to connect a serial device to the computer and capable of transmitting one bit at a time. Serial ports are typically identified on IBM compatible computers as COM (communications) ports.
Serial ports are generally built into the mother board, which is why the connectors behind the casing that are connected to the mother board by a wire cable can be used to connect an exterior element.

What is the serial port used for?

Below is a listing of various hardware components that can be purchased and used with your serial port.
  » Mouse - One of the most commonly used devices for serial ports, usually used with computers with no PS/2 or USB ports and specialty mice.
  » Modem - Another commonly used device for serial ports. Used commonly with older computers, however, is also commonly used for its ease of use.
  » Network - One of the original uses of the serial port, which allowed two computers to connect together and allow large files to be transferred between the two.
  »Printer - Today, this not a commonly used device for serial ports. However, was frequently used with older printers and plotters.

Serial port pin information

Below is a listing of each of the pins located on the DB9 connector, their purpose, and signal name.

1 Data Carrier Detect DCD
2 Received Data RxData
3 Transmitted Data TxData
4 Data Terminal Ready DTR
5 Signal Ground Gnd
6 Data Set Ready DSR
7 Request To Send RTS
8 Clear To Send CTS
9 Ring Indicator RI