Who knows the gtx45R? From what I am gathering, RS-232 (1) is used for GSU-25(adahars) RS-232 (2) is for the GDU 4xx (G3X touch screen). Do I just use RS-232 (3) for the GPS 20 input?

I guess what I am asking is I am running the GPS-20, which is providing wass gps signal to the transponder. Isn't the transponder going to use waas gps position and altitude from the transponder? So do I still provide info from the GSU-25, which is providing altitude via static pressure?