Serial Port Mapper allows you to map any serial ports to any other serial ports. For example you install additional serial port expansion card to computer as COM7 serial port but your favorite software can work with COM1...COM4 ports only. To resolve this problem you can use Serial Port Mapper to map new COM7 port either to COM1 or to COM2...COM4. Now your software can open COM1 port (or COM2...COM4) but actually work with new COM7 port.