G3x and 275: are they supposed to communicate?

[icurnmedic]

Still going through the new set up, CFI was setting parameters on the 275 and noticed that the parameters were not applied to the G3x and vice versa. The reason I ask is, if the 275 is the backup to the G3x, should it not also direct the gfc500 if the G3x fails ?
Many other questions to come I’m sure, thanks.

Thomas

[LANCECASPER]

I'm sure others will chime in, but what I've heard so far is that the G5 and G3x were designed to work together and the GI-275 and the G500TXi talk well together. 

The way I understood it is if the G3X went black then the G5 could do everything including the autopilot. 

 

[PT20J]

6 hours ago, LANCECASPER said:

I'm sure others will chime in, but what I've heard so far is that the G5 and G3x were designed to work together and the GI-275 and the G500TXi talk well together. 

The way I understood it is if the G3X went black then the G5 could do everything including the autopilot. 

 

That’s correct. While the GI 275 can be the required backup for the G3X under the STC, it cannot interface with anything which makes the G5 a better choice.

EDIT: Added second page.

[IFLYIFR]

PT20J, what document did you just send in your prior text? I would like to download it. Thanks. John.


Sent from my iPhone using Tapatalk

[201Mooniac]

The document details are in the footer shown on the page:  Instruction Manual G3X Touch EFIS Part 23 AML, STC, part number 190-02472-01, Revision 7.  Since this is an installation manual, you might have trouble finding it unless you look at the experimental version.

[rbp]

I had a 275 on order, and went with the G5 because of the above, confirmed by my avionics installer

[icurnmedic]

Well darn. Now I know. I had always wondered why the G5 was so much more popular. Thanks. 
Thomas

[LANCECASPER]

9 hours ago, icurnmedic said:

Well darn. Now I know. I had always wondered why the G5 was so much more popular. Thanks. 
Thomas

It would have been nice if your avionics shop knew enough about the equipment to steer you in the right direction.

[MAL]

I found this out AFTER my install was complete!  I was testing my G3X with GI275 backup after the installation noticing that Baro was not synchronizing between the two.  After calling my Avionics guy about it (as he had assured me "The GI275 does everything the G5 does, but better" ) he tells me "Oh, it turns out I was wrong there. . the GI275 can't talk to the G3x, or drive the auto-pilot (GFC500).  

Further researched confirmed it basically has to do with that fact that GI275 is not certified to talk CanBus, which is what is needed for it to talk to the G3x, the GFC500, and the GTN. So is basically just an expensive and 'dumb' ADI. The G5 can talk Canbus, so it can play nice with my other equipment.

Soo. . flash forward a few months and I am talking to my NEW Avionics guy about swapping out the GI275 with a G5.   The good news is that he just got back to me today and said he spoke with Garmin and they are promising the GI275 will be certified for Canbus "Within 12 months". So now I have to decide if I 'wait it out', or perform the G5 swap.

 

[Cruiser]

from the GI275 install manual page C-14
[13] Garmin autopilots can interface to a GI 275 ADAHRS unit (i.e., a GI 275 ADAHRS+AP unit is not required).

[18] For interface approval with the GFC 500, refer to GFC 500 STC SA01866WI

 

[PT20J]

46 minutes ago, MAL said:

I found this out AFTER my install was complete!  I was testing my G3X with GI275 backup after the installation noticing that Baro was not synchronizing between the two.  After calling my Avionics guy about it (as he had assured me "The GI275 does everything the G5 does, but better" ) he tells me "Oh, it turns out I was wrong there. . the GI275 can't talk to the G3x, or drive the auto-pilot (GFC500).  

Further researched confirmed it basically has to do with that fact that GI275 is not certified to talk CanBus, which is what is needed for it to talk to the G3x, the GFC500, and the GTN. So is basically just an expensive and 'dumb' ADI. The G5 can talk Canbus, so it can play nice with my other equipment.

Soo. . flash forward a few months and I am talking to my NEW Avionics guy about swapping out the GI275 with a G5.   The good news is that he just got back to me today and said he spoke with Garmin and they are promising the GI275 will be certified for Canbus "Within 12 months". So now I have to decide if I 'wait it out', or perform the G5 swap.

 

This has caught a lot of installers because the limitation is not on the GI 275 installation manual — it’s in the G3X installation manual. It is the G3X STC that would need to be changed. 

While the G3X STC allows the GI 275 to be used as the required standby instrument, there are severe limitations relegating the GI 275 to just being an expensive attitude indicator. From the G3X installation manual, Appendix F:

F.2 GI 275 Interfaces The GI 275 has no interface to the G3X system. The following paragraphs provide more detail about interface limitations and requirements for the GI 275 installed as a G3X standby instrument.

F.2.1 Magnetometer and OAT Probe The G3X system and GI 275 standby instrument cannot share the same GMU 11 magnetometer and GTP 59 OAT probe.  If magnetic heading, OAT, TAS, and standard rate turn bank angle pointers are desired to be displayed on the GI 275, an additional magnetometer and OAT probe must be installed for the GI 275.  Reference the GI 275 Part 23 AML STC Installation Manual for details.

F.2.2 External Navigators When used as a standby instrument for G3X, external navigators may not be interfaced to the GI 275. 

F.2.3 Autopilot The GI 275 STC supports a variety of interfaces to compatible autopilots for the GI 275 ADAHRS+AP model.  When used as a standby instrument for G3X, the approved autopilot interfaces for the GI 275 are limited to Gyro (attitude), Baro Correction, and Yaw Rate.  Interfaces for Flight Director, GPSS, and HSI (heading error and course error) may not be connected to the GI 275. 

[201Mooniac]

As Skip says, it is a G3X limitation, my GI-275 drives my GFC-500 AP (over CAN Bus) perfectly well and connects to my G500 TXi (over HSDB) for syncing all data as doing AHRS monitoring.

[PT20J]

1 hour ago, MAL said:

I found this out AFTER my install was complete!  I was testing my G3X with GI275 backup after the installation noticing that Baro was not synchronizing between the two.  After calling my Avionics guy about it (as he had assured me "The GI275 does everything the G5 does, but better" ) he tells me "Oh, it turns out I was wrong there. . the GI275 can't talk to the G3x, or drive the auto-pilot (GFC500).  

Further researched confirmed it basically has to do with that fact that GI275 is not certified to talk CanBus, which is what is needed for it to talk to the G3x, the GFC500, and the GTN. So is basically just an expensive and 'dumb' ADI. The G5 can talk Canbus, so it can play nice with my other equipment.

Soo. . flash forward a few months and I am talking to my NEW Avionics guy about swapping out the GI275 with a G5.   The good news is that he just got back to me today and said he spoke with Garmin and they are promising the GI275 will be certified for Canbus "Within 12 months". So now I have to decide if I 'wait it out', or perform the G5 swap.

 

I would be very careful about any claims made via Garmin support as I have not always found them to be a reliable source of information. Ditto with many installers. The GI 275 most certainly is certified for CAN Bus since that's how it interfaces with the GFC 500 in a non-G3X installation.

If I were in your position, I would contact Joey  Ferrerya, Garmin sales and customer experience manager, and explain your situation and see what he says. He's always been straight with me. joey.ferrerya@garmin.com

Skip 

[MAL]

Thanks for the contact! I'll reach out to Joey.

[PT20J]

On 5/5/2023 at 1:42 PM, MAL said:

Thanks for the contact! I'll reach out to Joey.

It appears that G3X v9.15 fixes this. It will require wiring changes. I would get with my dealer and review the G3X AML STC Installation Manual Rev 13 (MDL Rev 15).

https://support.garmin.com/en-US/?faq=k6HsnoUBSm5HLK5X7Twj19

Skip