Originally Posted by Avanza
I believe that ARINC 429 contains vertical navigation and RS 232 the lateral
information. So RS 232 has to be connected to the autopilot.
As I am considering upgrading to a 175/375 this is news to me, according to the gemini A/P manual if both 429 and 232 are connected the A/P defaults to the 429 input and rolls back to the 232 if no 429 signal is detected. It also states that you have to have 429 for coupled (3 dimensional) approaches i.e vertical guidance. I currently use the Aera 796 to drive the Gemini via 232 and was planning to couple the 175/375 via 429 and if for some reason it quits I can roll back to the 796 for GPS guidance (just not vertical).
I was also planning to connect the 2nd 429 channel from the 175/375 to the D100 to drive the CDI via the HS34 so that I could cycle through the SL30 VOR/ILS, 175/375, and Aera 796 navigation inputs.
I am no expert and currently studying for the instrument rating but would like to understand the interconnectivity as I plan my upgrade.