null-modem emulator

com port to com port https://sourceforge.net/projects/com0com/files/com0com/3.0.0.0/

https://sourceforge.net/projects/com0com/?source=typ_redirect

http://com0com.sourceforge.net/

virtual serial port driver (shareware)

https://www.youtube.com/watch?v=zcDtjKdQyMo

how to use libusb

http://stackoverflow.com/questions/17239565/how-to-most-properly-use-libusb-to-talk-to-connected-usb-devices