To monitor (bi-directional) Serial communication RS-232 between two devices without physical cable, use Bill Serial Monitor. This program allows you to view, log, test and analyse the activity of the serial RS-232 port. To monitor the serial protocol of two different serial devices. DSR, CTS, DTR and RTS can also be controlled. No programming or additional hardware required !

The license of this software is Free Trial Software, the price is $95, you can free download and get a free trial.