Originally Posted by DeeCee 57
+1 on Steve’s answer.
No need for an encoder, neither external nor the one for the 375... the G5 will provide that info.
Not to thread drift too much, but Dan is right.
If you have a G5 system with a Garmin GNX 375 or other Garmin Mode S ADS-B transponder like the GTX 335/345, these transponders automatically receive altitude data from the G5 over ARINC 429 (via the GAD 29), so there no need to connect the G5 RS-232 to the GTX.
If you have dual G5 units, you even have backup altitude data for the transponder via the CAN bus connection to the GAD 29.