A virtual serial port is a trade term used by certain vendors of COM port redirector software that emulates a serial port (RS-232, RS-422, and RS-485). This port is created by special software products which enable extra serial ports in operation system without additional hardware installation (such as expansion cards, etc.). Unlike the standard physical serial port the virtual one can be assigned any name (COM255, VSP33, etc.) to. It is possible to create unlimited number of virtual serial ports in your PC. The only limitation is the performance capacity of your system, as it may require a substantial amount of resources to emulate say 255 serial ports on slow computers.
Virtual serial port emulates all serial port functionality, including Baud rate, Data bits, Parity bits, Stop bits, etc. Additionally it allows controlling the data flow, emulating all signal lines (DTR/DSR/CTS/RTS/DCD/RI) and customizing pinout (only advanced solutions).
Serial ports emulation can be useful in case there is a lack of available physical serial ports or they do not meet the current requirements. For instance, virtual serial ports can help you share data between several applications from one GPS device connected to serial port. Another option is to communicate with any other serial devices via internet or LAN as if they are locally connected to computer (Serial-over-Ethernet technology). You can establish connection between two computers or applications via emulated null-modem link. Most of the available virtual serial port emulators are compatible with Windows 9x, Windows NT, Windows 2000, Windows ME, Windows 2003, Windows XP and some of them run under Windows CE, Windows Mobile and Pocket PC.
Virtual serial ports are available as both commercial products and free software.
Virtual Serial Port Driver (VSPD) turns serial ports of Tibbo Device Servers into remote COM ports of your PC. VSP Manager is used to create and manage Virtual Serial Ports (VSPs).