Serial Port Mapper allows to map any serial port to any new port name. In other words, it allows to create aliases for serial ports.
For example, you install additional serial port expansion card to computer as COM5 serial port. But your favorite software can work with COM1...COM4 ports only and cannot be reconfigured to work with COM5.
To resolve this problem you need to map COM5 port to COM1 port. As result, your software can open COM1 port but actually work with COM5 port.