Share Serial Ports 

Share Serial Ports creates virtual serial ports in your system that appear as copies of real ports and allows you to share real serial ports between multiple applications. All applications will be able to receive and send data to serial port.
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Virtual Serial Port Kit 

Virtual Serial Port Kit creates pairs of virtual serial ports in your system which are virtually connected to each other. Physical null modem cables are not required. You can connect any number of virtual port pairs. It's very useful for debugging.
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VSPD.net 

Network Virtual Serial Ports Driver is an advanced utility, the purpose of which is to emulate null-modem cable on computers located in a TCP/IP LAN or connected to the Internet by creating any number of pure virtual serial ports in your system.
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