I have two raspberry pis I want to communicate between. For convenience, let's say one is always the talker and the other is always the listener. The listener's ethernet port is occupied by another connection. Is there a way I can send messages from the talker to the listener over an RJ45-RS232USB cable? The RJ45 connects to the talker and shows up at the listener side as /dev/ttyUSB0. Is there a way I can write a message (maybe UDP) to the port on the talker end and have it appear on the serial port at the listener end?