G5 Dual Nav with GTN: Mapmx really required?

[sumitku]

@Longez @g3xpert

My configuration is dual g3x touch with a backup G5, GTN 650xi and SL-30.

I’ve spent a bunch of time searching various threads and pouring through both the experimental and stc install manuals.

The target is to install the SL-30 on the G5 rs-232 as vloc 1 and the GTN (through GAD 29) arinc for gps/vloc 2.

Assuming I add an external GPS antenna for the G5, my question is if the Mapmx rs-232 tx from gtn to the g5 rx is really required.

In various threads Ive seen it stated that this Mapmx is connection is required for one of the following inconsistent reasons:

- Mapmx required for high quality gps aiding for G5 attitude solution (but not required if g5 has strong bezel antenna reception or an external antenna)

- Mapmx from gtn to g5 required for g5 to be able to fly coupled approaches with the gtn. Is this true, as I believe many installations ive come across such as the avidyne entegra efis with stec 55x can perform fully coupled nav/approaches with only arinc connections from the GTN?

- referring to Figure 7-13 of the current revision 10 of the G5 experimental installation manual, this dual nav confirmation has the Aera 660 using up the rs232 connection with NMEA and the GTN connected only over arinc, suggesting there is no limitation relative to autopilot coupled lateral and vertical navigation from the gtn over only arinc with no Mapmx rs232

Hoping I’m able to confirm that the Mapmx is unecessary therefore allowing me to connect the SL30 using the rs232 and gtn only with arinc

Thanks!

Sumit

 

[mburch]

The target is to install the SL-30 on the G5 rs-232 as vloc 1 and the GTN (through GAD 29) arinc for gps/vloc 2.

Yes, this is the only supported configuration for this combination of navigators. For this type of installation I would use a dedicated GPS antenna for at least one G5.

 

[sumitku]

Yes, this is the only supported configuration for this combination of navigators. For this type of installation I would use a dedicated GPS antenna for at least one G5.

Thanks Matt. I’ll only have the one g5, in backup set up, for the dual gdu460s. Definitely planning the dedicated antenna for the g5. I’ve just seen many instances where it’s been suggested that the Mapmx 232 connection from the gtn is mandatory. I’m hoping not to find out that this ends up somehow being the case after wiring it all up.

 

[mburch]

I’ve just seen many instances where it’s been suggested that the Mapmx 232 connection from the gtn is mandatory.

This connection is always mandatory for a GDU, but is only mandatory for a G5 if the GTN will be the sole source of GPS data for the G5.

 

[sumitku]

This connection is always mandatory for a GDU, but is only mandatory for a G5 if the GTN will be the sole source of GPS data for the G5.

Perfect thanks.

 

[sumitku]

Just discovered another probably gotcha. In the g3x touch installation manual, any connected GPS navigator is automatically assigned to nav 1 slot for the gdus, and I’d have to correspondingly set the gtn sdis to #1.

On the G5, any nav unit connected to the rs-232 port is assigned to nav 1, making the sl30 nav 1, and the GTN on the GAD 29 arinc nav 2, meaning I’d have to set the gtn sdis to #2.
Post in thread 'Garmin G5 and NAV'
https://vansairforce.net/threads/garmin-g5-and-nav.157235/post-1427475

In short, I don’t believe the desired config to have both the sl30 and gtn on both the gdus and the g5 is going to work.