Using the G5 as an altitude encoder for Stratus ESG

I finally bit the bullet and installed ADSB-out in our RV-6A this weekend. I also put two Garmin G5's in and pulled the vacuum pump, directional gyro and attitude gyro. Pretty easy all around except hooking up the G5 altitude encoder function to the Stratus ESG. I got the wires right (single line from RS232 TX - pin 5 - on the G5 to RS232 RX Altitude - pin 5 - on the Stratus). When I fired up the boxes, I got ----- for altitude on the Stratus, and field elevation on the G5, so I knew they weren't talking.

I called Garmin and experimental support guy told me it wouldn't work. I argued that RS232 is a standard, and it "should" work. Called Greg at the Stratus installation support line and he didn't know how to hook the two boxes together . . .

So, I started looking for a way to change communications settings.

Turns out you have to scroll to the bottom of the G5 configuration menu to "RS232 Configuration" and change Output Format to "Altitude" and the Baud Rate to "9600". Works fine and saved me the cost of an altitude encoder.

I wish more experimental guys worked at these companies. It's not the first time I've had to figure out things about their products that they should know, but haven't played around enough to discover.

To be fair, RS232 has well established electrical standards. However, the software (?format?) is another story. Some formats are open-sourced and well standardized. But other formats are held as proprietary secrets by the company that wrote them (Garmin?s ADSB+, for example). Not all boxes can send or read all formats. So company A?s rep may or may not know if company B?s box can read a certain format, and vice versa. It would be nice if it were so, but after all they don?t work for company B.
BTW, ?adding another encoder? is not an option. ADSB rules require one altitude source to supply the pressure altitude data to both the transponder and the adsb-out.

I used my G5 back in May as the encoder for my Stratus ESG. I figured it out for myself just by reading the G5 manual. I did all the wiring and installation. I even had 91.411 and 91.413 completed. They found that both G5s need calibrated and included that in the test. Flew the setup after the Pitot / Static / Transponder test and received the $500 rebate. Has worked great but only 15 or so hours on the new equipment.