[ExtraKatana]

Trying to get me Sport 10.1 to talk with my Apollo SL40 ans SL70.

The pinouts drawings for each radio/xponder say there is a return serial to the EFIS, but in parenthesis (ground). Is the return Serial actually going to Ground of the EFIS or the return serial pin?

I have the EFIS sending squak info to the xponder bit I’m getting an error message that the EFIS is not receiving from the radio.

 

[Canadian_JOY]

Sounds a whole lot more like mis-pinning of a connector or mis-configuration of the serial port on the EFIS. As long as the EFIS and radio share a common ground (e.x. both are tied to the same metal instrument panel or similar) the RS232 returns generally don't require a lot of attention. In fact many people leave them out entirely and just rely on airframe grounding between the radios to carry the return.

 

[ExtraKatana]

GRT dis respond with the response I was looking for. Thanks for the others also.