Having battling intermittently for the past two weeks to get an Arduino to "emulate" the Yaesu serial protocol I finaly got it, I can set frequency and mode from the rig control software on to the Arduino:
Setting the frequency:
I didn't take the new frequency set picture (set freq) but it did worked. Mode "8" is the hex sent from the rig control software for FM mode.
Tried to find some other similar project and found none so have to make it myself, far as I know this is one of a kind! There are some projects but are to control an Yaesu radio from an Arduino, not the RIG CAT software to control the Arduino. The idea is remotely controlling the VFO of the "Trevo" transceiver (the one I've been building for the last year)
Will release the code if there's any interest and after beeing well polished... it will take time.
add: code: http://speakyssb.blogspot.ie/2014/10/my-arduino-thinks-he-is-yaesu-arduino.html
Have a good weekend!