Hi to all!!!
I have an FT-991, an FT-897 and FT-817. The FT-991 have the built-in serial defunct (only the audio section is working) and I use an RS232 adapter connected to the DB-9 (GPS/CAT) connector on the rear. The other ones uses the original SCU-17 interface, that provide 2 Serials and the 2 audio devices.
Is there a solution to use the CAT with Direwolf (for APRS or packet) instead the RTS?