[negrini]

Your approach seems confusing too ! First, make sure your AIS output is working at some baudrate. Connect a RS-232 laptop input (should work although RS-422 is not 100% compliant to RS 232), open a terminal and find the correct bps combination. You should not go over next steps until you find the correct baudrate, stop bit lenght and parity; this way you grant your AIS is puting sentences out. Next, connect it directly to your C70 NMEA as your AP might not be bridging AIS correctly, no matter if worked before. The voltage you measure has almost no meaning as this is a pulse, and the RS-422 is indeed a current loop rather a voltage sensitive. Should be a simple matter of carefully approachung your system by following the data path in steps. Good luck .....