I’m just now reading this thread after having an issue with a shop doing a cert on a transponder. But here’s the skinny on the altitude
The install manual for the GTX 335/345 is the only place you will find the G5 providing the altitude. However it is listed as the GAD29B. the GAD takes info in the form of rs232 and arinc429 compiles the data and spits it out on the can bus for the G5s. The altitude goes to the transponder on a 429 line additionally the altitude is corrected and uncorrected. So, regardless of baro setting the transponder is only getting 29.92. The transponder gets all of the info on the data line and only takes what it’s looking for.
hope this helps, Angel
