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Posted: Thu Mar 28, 2019 12:00 pm
by JimB
I have a GNS430 connected to my Sport HS using RS232 and ARINC. I'm considering upgrading to a separate GPS (GPS 175) and Nav-Comm (GNC255). With the 430 I use the CDI button to switch between GPS and VORLOC mode. With two independent units how does the EFIS "know" to use the Nav-Comm ARINC data for a ILS rather than the GPS data?


Jim Butcher

Re: Interface

Posted: Thu Mar 28, 2019 11:01 pm
by Bobturner
I have a Horizon but it’s probably the same. Push the right hand button to bring up all the button labels. On the (I think) second from the right button you see labels for VOR-Loc#1, GPS#1, etc. Select the nav source you want. You must have your current setup set to ‘auto switch with Garmin CDI button’ or something like that. You’ll want to turn that off. And you’ll need to identify the new radios as vor#1, gps#1, etc.

Re: Interface

Posted: Fri Mar 29, 2019 2:12 am
by GRT_Jeff
Change "NAV Mode Source" to "Internal" (General Setup) and you will have separate GPS and NAV selections on your NAV MODE button.

Does the 175 have the same ARINC-429 GAMA 429 interface as the GNS and GTN units?

Re: Interface

Posted: Fri Mar 29, 2019 11:13 am
by JimB
Thanks Jeff.

I haven't seen any install docs so I'm only guessing that ARINC would be the same.