I figured that I would post what I had to do to get my Garmin Aera 510 GPS to talk to the D180 and the GTR225 Comm. I recently installed a Garmin GTR 225 Comm radio in my RV-9A. I wanted to connect the Comm to my Aera 510 to take advantage of the nearest feature of the radio. I purchased the radio from Aircraft Spruce and it came with the harness. First off the harness that came with the GTR 225 is NOT complete for this installation. I connected pin 16 from the GTR 225 (this wire was included in the harness) to the RS232 data out wire from the GPS (blue wire). You need to connect pin 34 of the GTR 225 to the same data ground used of the GPS and D180. This pin was NOT included in the harness. The data cable supplied was marked data "white" and ground "blue stripe" but this is not connected to pin 34 "RS232 ground. Their are several wires that I did not use so I moved it to the pin 34 location. Once connected I configured the GTR 225 for NEMA because this the data stream that I have been flying with the Aera and D180 for the past two years and the combination has worked well.
NO JOY the 225 did not see the GPS data.
I did get everything to work by:
1. Reconfiguring the GPS data stream to "Aviation in / NEMA & VHF out", speed "normal".
2. The D180 settings are HSI ... Local Data Port EFIS/EMS SERIAL, input auto, Baud 9600, EMS auto, and 9600 Baud.
3. GTR 225 Serial data IO to NEMA.
NO JOY the 225 did not see the GPS data.
I did get everything to work by:
1. Reconfiguring the GPS data stream to "Aviation in / NEMA & VHF out", speed "normal".
2. The D180 settings are HSI ... Local Data Port EFIS/EMS SERIAL, input auto, Baud 9600, EMS auto, and 9600 Baud.
3. GTR 225 Serial data IO to NEMA.