Review on 🔌 DTECH USB to RS422 RS485 Serial Port Converter Adapter Cable - Support for Windows 10 8 7 XP Mac - High-Quality 1.5 Feet Cable with FTDI Chip by Uriel Arocha

Works! It took me a while to figure it out, but one day it was more or less obvious. It's helpful to look at the FTDI reference design for the 422 converter, and as mentioned earlier (and a line in the user guide), 120 ohm terminators are recommended at the ends of long, high-speed cables. When I needed to connect to a Garmin 19x at the end of a 30m cable in my case, they weren't needed. The "trick" that took me ages was that I first hooked up the Garmin TX to DTech's TX lines - it didn't work. Changed polarity and lo and behold I could see the data. But then I couldn't send messages to Garmin. After some downtime I properly connected the Garmin TX to the DTech RX and the Garmin RX to the DTech TX and it worked. I also had to reverse the polarity, but now everything works great!