If you have the Instrument Control Toolbox, just use tcp() directly instead of receiving by netcat. If you do not have that toolbox, look in the File Exchange for tcpudpip()
If you want to stick to netcat then you need to send its output to a file, and you need to open the file and read from it, instead of trying to use a serial port. Depending on your operating system and exact needs, you might want to write to a fifo (created with mkfifo) instead of a file.
