Serial device server, also known as serial line end server or port redirector internationally, is a device that transfers data between computer serial port (COM port) and Ethernet local area network (LAN). This allows Ethernet to be used to replace serial port devices, reducing workstation clutter to the largest extent, and allows serial devices to be placed far from the computers that use them.
Serial device server is available for all types of serial port devices and peripherals, such as printers, scanners, data acquisition terminals, display equipment, modems, automation equipment, safety/alarm systems and climate control systems. Most serial device servers provide multiple serial devices to connect to a single serial port. Serial server can be used for hardwired or wireless Ethernet LAN. Some serial servers can also run across Internet Protocol (IP) wide area network (WAN) to access remote serial devices, as if they are directly connected to the COM port of a personal computer or web server. The latter serial device server is sometimes referred to as an Ethernet modem.