Virtual Null Modem Device: The purpose of a null-modem cable is to permit two RS-232 "DTE" devices to communicate with each other without modems or other communication devices (i.e., "DCE"s) between them.Virtual Null Modem is an utility, which purpose is to emulate one or more RS232 serial ports connected via virtual null-modem cable. Otherwise, you can create any number of pure virtual serial ports in your system (COM10, COM11, COM127 etc), that will be connected to each other via virtual null-modem cable.