A serial port server, also called a serial server or port redirector, is a device that transfers data between a computer serial port (COM port) and an Ethernet local area network (LAN). This makes it possible to use Ethernet in place of serial cables, minimizing workstation clutter and also allowing serial devices to be placed far away from the computers with which they are used.
Serial port servers can be used with all types of serial devices and peripherals. Examples include printers, scanners, data collection terminals, display devices, modems, automation equipment, security/alarm systems, and climate-control systems. Most serial port servers provide for multiple serial devices to be connected to a single serial port. Serial port servers are available for hard-wired or wireless Ethernet LANs. Some serial port servers can also function across Internet Protocol (IP) wide-area networks (WANs), making it possible to access distant serial devices as if they were directly connected to the COM port of a personal computer or network server. The latter kind of serial port server is sometimes called an Ethernet modem.