What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Sanity Check on G3X/GTN Data Connections

I

iamtheari

Well Known Member
I am almost ready to start wiring my panel. I am installing a G3X PFD and MFD, a GTN 650, a GTX 45R, a GTR 20, and the miscellaneous support LRUs. Before I commit my pin-by-pin spreadsheet to wires, I want to make sure I am not doing something extraneous or missing something with the numerous data connections. In addition to the CAN bus and the dedicated RS-232 connections between the GSU 25's and the GDU 460's, here is what I have written down:

PFD RS-232 #1 <-> GEA 24 for redundancy
PFD RS-232 #2 <-> GTN 650 RS-232 #1, config MapMX format
PFD RS-232 #3 <-> GTN 650 RS-232 #2, config Connext format
PFD RS-232 #4 <- GD-40 CO detector for alerts
PFD RS-232 #5 <-> GTX 45R RS-232 #2 for traffic and weather

MFD RS-232 #1 <-> VP-X Pro
MFD RS-232 #2 -> ELT for position source
MFD RS-232 #5 <-> GTX 45R RS-232 #3 for traffic and weather

GSU 25 <-> GTX 45R RS-232 #1 for air data

GTN 650 ARINC #1 <-> GAD 29 ARINC #1 for GPS navigation data
GTN 650 ARINC #2 <-> GTX 45R for position source
GTN 650 Nav ARINC -> GAD 29 ARINC #2 for VHF nav data
GTN 650 Ethernet #1 <-> GTX 45R Ethernet #1


Questions I know enough to ask:
1. Can the GTN -> GTX position source ARINC data be one-directional?
2. Is the ethernet connection between the GTN and GTX necessary or is the ARINC connection adequate?
3. Are there any connections I am not making that I should, to enable convenient features in any of these devices?
4. Are there any questions I don't know enough to ask when it comes to the data connections among these devices?

Thanks, everyone! I'm looking forward to the spaghetti factory phase of my built.
 
iamtheari said:
I am almost ready to start wiring my panel. I am installing a G3X PFD and MFD, a GTN 650, a GTX 45R, a GTR 20, and the miscellaneous support LRUs. Before I commit my pin-by-pin spreadsheet to wires, I want to make sure I am not doing something extraneous or missing something with the numerous data connections. In addition to the CAN bus and the dedicated RS-232 connections between the GSU 25's and the GDU 460's, here is what I have written down:

PFD RS-232 #1 <-> GEA 24 for redundancy
PFD RS-232 #2 <-> GTN 650 RS-232 #1, config MapMX format
PFD RS-232 #3 <-> GTN 650 RS-232 #2, config Connext format
PFD RS-232 #4 <- GD-40 CO detector for alerts
PFD RS-232 #5 <-> GTX 45R RS-232 #2 for traffic and weather

MFD RS-232 #1 <-> VP-X Pro
MFD RS-232 #2 -> ELT for position source
MFD RS-232 #5 <-> GTX 45R RS-232 #3 for traffic and weather

GSU 25 <-> GTX 45R RS-232 #1 for air data

GTN 650 ARINC #1 <-> GAD 29 ARINC #1 for GPS navigation data
GTN 650 ARINC #2 <-> GTX 45R for position source
GTN 650 Nav ARINC -> GAD 29 ARINC #2 for VHF nav data
GTN 650 Ethernet #1 <-> GTX 45R Ethernet #1


Questions I know enough to ask:
1. Can the GTN -> GTX position source ARINC data be one-directional?
2. Is the ethernet connection between the GTN and GTX necessary or is the ARINC connection adequate?
3. Are there any connections I am not making that I should, to enable convenient features in any of these devices?
4. Are there any questions I don't know enough to ask when it comes to the data connections among these devices?

Thanks, everyone! I'm looking forward to the spaghetti factory phase of my built.
Click to expand...
Hello Ari,

Fortunately, there are only a few pages in section 27 of the G3X Touch Installation manual which show how to wire all of this equipment.

The first error is the A429 connection between the GTX 45R and the GTN. As shown on page 27-30 of the current Rev. AK manual, the only connection between the GTX 45R and the GTN is the Ethernet connection.

As explained on that page, the bi-directional Ethernet connection allows the GTN to provide GPS position data to the GTX 45R, while the GTX 45R provides traffic/weather to the GTN.

The second error is that one of the 3 A429 connections between the GAD 29 and the GTN 650 appear to be missing (EFIS/Airdata). See page 27-36.

Thanks,
Steve
 
g3xpert said:
Hello Ari,

Fortunately, there are only a few pages in section 27 of the G3X Touch Installation manual which show how to wire all of this equipment.

The first error is the A429 connection between the GTX 45R and the GTN. As shown on page 27-30 of the current Rev. AK manual, the only connection between the GTX 45R and the GTN is the Ethernet connection.

As explained on that page, the bi-directional Ethernet connection allows the GTN to provide GPS position data to the GTX 45R, while the GTX 45R provides traffic/weather to the GTN.

The second error is that one of the 3 A429 connections between the GAD 29 and the GTN 650 appear to be missing (EFIS/Airdata). See page 27-36.

Thanks,
Steve
Click to expand...
Thanks for responding so quickly and precisely. I was using revision AH of the manual. Not sure if there was a change to the drawings or if I was misinterpreting a drawing in the GTN and/or GTX manuals. But I will get rid of the extraneous ARINC 429 connection from the GTN to the GTX.

I did have the connections from the GAD to the GTN correct, although I didn?t label them well in my post. The <-> is a bidirectional link although I suppose ARINC 429 doesn?t work that way and the actual data is not bidirectional.


Walt: I have those but didn?t mention them because they?re on their own connectors on the GDU?s. Good to double-check me on that!

Pilot2512: I am using a GMC 507, in part because of the simpler connection requirements. :)
 
While I?m here, the P4601 connector on the GDU 460 has two power outputs. I have been planning my wiring on the assumption that they will provide power to the GSU from the same two sources as the GDU gets its power. That is, P4601 pin 8 is internally connected to P4602 pin 32 and P4601 pin 7 is internally connected to P4602 pin 31. But I don?t see any drawings supporting that assumption, just a note to ?contact Garmin for details before using this method.?

What details might those be? :)
 
iamtheari said:
While I?m here, the P4601 connector on the GDU 460 has two power outputs. I have been planning my wiring on the assumption that they will provide power to the GSU from the same two sources as the GDU gets its power. That is, P4601 pin 8 is internally connected to P4602 pin 32 and P4601 pin 7 is internally connected to P4602 pin 31. But I don?t see any drawings supporting that assumption, just a note to ?contact Garmin for details before using this method.?

What details might those be? :)
Click to expand...
Hello Ari,

The GSU 25 ADAHRS is an independent unit on the CAN bus, used by many devices, and as such should generally have its own CAN and power connections. For example, should you ever want to power down a display, you might want to keep the GSU 25 powered so it could be used by the autopilot or another display.

The "Contact Garmin" note on that page pertains to installing the GSU 25 on the back of a display. We don't recommend that for a couple of reasons that have been previously discussed on this forum.

We have seen ADAHRS data for display mounted GSU 25 units which is fine, but we have also seen many installations where the vibration level was not acceptable, and the GSU 25 had to be relocated before acceptable performance could be achieved.

Thanks,
Steve
 
iamtheari said:
I am almost ready to start wiring my panel. I am installing a G3X PFD and MFD, a GTN 650, a GTX 45R, a GTR 20, and the miscellaneous support LRUs. Before I commit my pin-by-pin spreadsheet to wires, I want to make sure I am not doing something extraneous or missing something with the numerous data connections. In addition to the CAN bus and the dedicated RS-232 connections between the GSU 25's and the GDU 460's, here is what I have written down:

PFD RS-232 #1 <-> GEA 24 for redundancy
PFD RS-232 #2 <-> GTN 650 RS-232 #1, config MapMX format
PFD RS-232 #3 <-> GTN 650 RS-232 #2, config Connext format
PFD RS-232 #4 <- GD-40 CO detector for alerts
PFD RS-232 #5 <-> GTX 45R RS-232 #2 for traffic and weather

MFD RS-232 #1 <-> VP-X Pro
MFD RS-232 #2 -> ELT for position source
MFD RS-232 #5 <-> GTX 45R RS-232 #3 for traffic and weather

GSU 25 <-> GTX 45R RS-232 #1 for air data

GTN 650 ARINC #1 <-> GAD 29 ARINC #1 for GPS navigation data
GTN 650 ARINC #2 <-> GTX 45R for position source
GTN 650 Nav ARINC -> GAD 29 ARINC #2 for VHF nav data
GTN 650 Ethernet #1 <-> GTX 45R Ethernet #1


Questions I know enough to ask:
1. Can the GTN -> GTX position source ARINC data be one-directional?
2. Is the ethernet connection between the GTN and GTX necessary or is the ARINC connection adequate?
3. Are there any connections I am not making that I should, to enable convenient features in any of these devices?
4. Are there any questions I don't know enough to ask when it comes to the data connections among these devices?

Thanks, everyone! I'm looking forward to the spaghetti factory phase of my built.
Click to expand...


Is the proper interface for ADS-B position data the ARINC port or via RS232 serial port using ADSB+ protocol?

Nevermind - I see from the replies that position source info comes over the ethernet interface.
 
Last edited:
g3xpert said:
Hello Ari,

The GSU 25 ADAHRS is an independent unit on the CAN bus, used by many devices, and as such should generally have its own CAN and power connections. For example, should you ever want to power down a display, you might want to keep the GSU 25 powered so it could be used by the autopilot or another display.

The "Contact Garmin" note on that page pertains to installing the GSU 25 on the back of a display. We don't recommend that for a couple of reasons that have been previously discussed on this forum.

We have seen ADAHRS data for display mounted GSU 25 units which is fine, but we have also seen many installations where the vibration level was not acceptable, and the GSU 25 had to be relocated before acceptable performance could be achieved.

Thanks,
Steve
Click to expand...
Thanks. I've researched the mounting issues and it seems that people with RV-14's like I am building have had good luck mounting the GSU on the GDU, but I am still planning to mount my GSU's to the sub panel both to reduce the risk of vibration issues and so I can remove the GDU's without disconnecting the pitot/static/AOA system.

Meanwhile, as I continue working at my electrical plan, I do wonder if it's possible to wire it like this:

VP-X output A -> GDU power 1 (P4602/32)
VP-X output B -> GSU power 1 (J251/7)
IBBS output -> GDU power 2 (P4602/31)
GDU pwr 2 (P4601/8) -> GSU power 2 (J251/8)

In other words, can I use P4601 to daisy-chain the backup power to the GSU? I already have to turn off the backup battery completely to remove all power from the PFD and/or primary GSU, so having their backup power supplies wired together or separately makes no difference in that particular situation.
 
I would recommend making the wired connection between the 45r and MFD while you’re in there, but don’t use it. Use Bluetooth for the MFD so you can get the newer information that isn’t available through a wired connection (lightning, icing, etc.)
 
You must log in or register to reply here.
Back
Top