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Garmin GDL 39 will not connect to an autopilot?

GDL39 Autopilot Testing with TruTrak

This morning we connected a GPSMAP 696 with a bare wire cable to a GDL39 with a bare wire cable. We then connected the orange wire (port B transmit) coming out of the GDL39 bare wire cable to pin 6 (NMEA In) on a Trio GX Pro autopilot. We also grounded the unused white/orange wire (port B receive) coming out of the GDL39 so it wouldn't be floating and coupling noise into the GDL39 receiver.

The autopilot came out of No GPS mode immediately and ran solid with no problems for over an hour.

We also ran a test with the white/orange wire floating and saw the autopilot frequently revert to No GPS mode as we expected. After re-grounding the white/orange wire the autopilot operation was solid again.

Next up we will test a TruTrak autopilot.

Using the same GPSMAP 696, cables and GDL39, we also tested the ability to provide NMEA data to a TruTrak GX Pilot autopilot with it set to receive data at 4800 baud. We were wired to pin 17 on the GX Pilot.

It too worked fine and quickly reported GPS OK when the system was providing data.

Update: We tested this same interface with an Aera 5XX and it also worked correctly to drive the TruTrak autopilot.

Thanks,
Steve

GXPilot.jpg
 
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Steve, thanks for confirming that the 696 can work to drive both the Trio and the Trutrak autopilots. I guess both Mark and I will both have to come up with a reason it's not working in either of our installations. I cannot speak for Mark, but as for me right now I'm out of ideas. I followed the recommended wiring, have the latest firmware on both the 696 (v6.1) and on the GDL 39 (v2.3), yet it doesn't work. Would you be willing to email Trutrak the output capture file? Perhaps it's something to do with my particular model of Trutrak AP? I'm just trying to come up with some ideas....
 
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Steve, thanks for confirming that the 696 can work to drive both the Trio and the Trutrak autopilots. I guess both Mark and I will both have to come up with a reason it's not working in either of our installations. I cannot speak for Mark, but as for me right now I'm out of ideas. I followed the recommended wiring, have the latest firmware on both the 696 (v6.1) and on the GDL 39 (v2.3), yet it doesn't work. Would you be willing to email Trutrak the output capture file? Perhaps it's something to do with my particular model of Trutrak AP? I'm just trying to come up with some ideas....

Pboyce,

We have shared captured data with TruTrak and we discussed data content, timing, port setup, etc today.

We asked customer service to work with you to exchange your unit. When we get our hands on it we can either determine what is wrong or declare it healthy and operational. Either way, we should learn something.

We will get you going one way or the other.

Thanks,
Steve
 
Steve, do you have an update on getting the additional communication data to drive the SL30/40 radio frequency (along with NMEA data for autopilot)?

Hello Stephen,

Sorry for the delay in answering your question.

We will be releasing new Aera 5XX and GPSMAP 69X software soon that will allow all the devices that could previously be connected to a single serial port on these units to be connected to the GDL39 second serial port.

Thanks,
Steve
 
Steve,

Okay, I took my testing to another level. This time I connected an old laptop with serial port to GDL output using a terminal program. When connected to the B port it was deader than dead. When connected to the A port I got data per this screen shot.

GDLMonitor.jpg


It didn't connect long because of a stop bit error that I don't understand but at least it was showing data. The 'B's were with it in Nmea mode and then I switched to Garmin mode for the readable data. So in conclusion, I know port A is working (which we knew already) but B is dead. I did have B set to 9600 but tried 4800 as well with respective laptop serial port settings. And yes, I had the orn/wht wire grounded per your suggestion (and pin 5 grounded on laptop DB-9).

So my suggestion would be to have you send me a GDL that you've tested on the bench and know that it works. Or I can fly down to Garmin in Salem again and they can come out to the ramp for a few minutes this time and swap me out with one that they know works. Let me know what would work. Who knows, maybe you had a bad production run that a few of us have.

My friend George is ready to pull the trigger on buying a GDL but is waiting until I get mine working because he also needs to connect his to his 696 and autopilot.

I am curious to know if anyone on the forum has actually used port B successfully with a 696.

Thanks,

Mark
 
Hello Mark,

Thanks for putting this effort into troubleshooting.

Our factory automated test on the GDL39 performs a loop-back test on port B to verify that each unit can both transmit and receive on that port, so it is unlikely that a batch were produced with this problem.

Please email me at [email protected] and we will work with you directly. We have some ideas that we want to try out and your willingness to visit our facility in Salem opens up even more possibilities.

Thanks again and sorry for the trouble,
Steve
 
Thanks to everyone's help we have been able to reproduce and fix the pass through port issue that has been reported.

We will be releasing new Aera 5XX, GPSMAP 69X, and GDL39 software soon.

This software will also have expanded pass through port capability to support all the old interfaces as well as another new feature that we will provide details on when the software is released.

Thanks,
Steve
 
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It sure is great to see how fast issues can be fixed when the manufacturer actually works with and listens to their end users.

This is a major paradigm shift for Garmin and it is a change that I welcome with open arms!

Keep it up Steve!
 
New Software for Aera 5XX, GPSMAP 69X and G3X

Thanks to everyone's help we have been able to reproduce and fix the pass through port issue that has been reported.

We will be releasing new Aera 5XX, GPSMAP 69X, and GDL39 software soon.

This software will also have expanded pass through port capability to support all the old interfaces as well as another new feature that we will provide details on when the software is released.

This new software has been released (including GDL39 V2.40). All of the previously supported serial port formats like VHF out and TIS In are back in service and available through the Port B connection on the GDL39.

The new G3X software adds the new TargetTrend ADS-B traffic capability, but since G3X doesn't use/require the pass through port feature on the GDL39, those changes don't apply to G3X.

GPSMAP 69X V6.20
Aera 5XX V4.10
G3X V7.20

See this thread for some discussion of the new TargetTrend ADS-B traffic capability also provided by this release for Aera 5XX, GPSMAP 69X, and G3X (soon for Aera 79X).

Thanks,
Steve
 
Service

How about that! A lightning quick software update (which works perfectly, by the way) and it is posted for all to see at 6:38 in the morning! Very nicely done.
 
Good job Steve! With the new software my 696 now works great with the pass-thru serial port to the Trio ProPiot autopilot. I can also configure the port to work with the TIS on my 330 transponder just as it did before. I'll probably be upgrading it to ES and won't need the TIS but it looks like it works for now.

It's great to have someone from Garmin on the forum to help out with customer questions and issues.

Mark
 
Steve, I installed v6.2 this morning, which also updated the GDL 39 to v2.4. I set it to NMEA output and 'fast' and everything seems to work great! It definitely synced faster to the trutrak AP. I didn't get a chance to fly because of weather, so I did not test how it interacts with a flight plan on the 696, but so far so good. Thanks for all your work on this issue!
 
796 updates & Question

Waiting for UPS to deliver the 796 and GDL39 from Stein, few questions:
1. Noted a couple of times that 7XX updates coming later, what functionality is not available with this combo today (target trend?)
2. If I plug in the existing XM antennae and 3.5mm audio plug to the intercom I assume all the audio and XM functions will work as for the 496 that is being replaced
3. Do I need to wire the bare cable from the 796 to the GDL39 or is all functionality available via bluetooth
4. Serial out from the 796 bare wire works the same as the 496 (drives the A/P etc)
 
Waiting for UPS to deliver the 796 and GDL39 from Stein, few questions:
1. Noted a couple of times that 7XX updates coming later, what functionality is not available with this combo today (target trend?)
2. If I plug in the existing XM antennae and 3.5mm audio plug to the intercom I assume all the audio and XM functions will work as for the 496 that is being replaced
3. Do I need to wire the bare cable from the 796 to the GDL39 or is all functionality available via bluetooth
4. Serial out from the 796 bare wire works the same as the 496 (drives the A/P etc)

Hello Dave,

1. The next release of Aera 79X is expected to have Bluetooth connectivity to the GDL39 and the TargetTrend traffic feature. Meanwhile, it works great over a cable to the GDL39.
2. As long as you have a GXM40, your existing XM receiver should work with your new 796, or you can transfer your account over to your new GXM40. The audio connection should work as well.
3. See 1. above regarding Bluetooth, but yes, when BT is available you have the option to just use BT to connect the GDL39. If you are using a bare wire cable on the Aera 796 and want to also use a cable to connect the GDL39, you will need to use a bare wire cable on the GDL39 as well.
4. Since the Aera 796 has 2 serial ports, you can connect the GDL39 to one port and your other devices (like autopilot) to the other port.

Thanks for your support,
Steve
 
Nothing to do with AP's and data lines but most of you should have had the rebate as well:

Got my free GDL39 case in the mail today from the Garmin rebate. Cool...

Did not get the GDL battery yet, must be coming from a different location.
 
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Sorry to resurrect this thread again. I am in the process of installing a Garmin GTR 200 radio and have to revisit the need of pass through in my GDL 39. I have an Aera 510, GDL 39, and now the GTR 200 radio.

Question, does the orange/wht wire still need to be grounded coming out of the GDL 39 or did the software fixes remedy that? I have two devices needing GPS data, the GTR 200 and my FDS fuel flow gauge.
 
Sorry to resurrect this thread again. I am in the process of installing a Garmin GTR 200 radio and have to revisit the need of pass through in my GDL 39. I have an Aera 510, GDL 39, and now the GTR 200 radio.

Question, does the orange/wht wire still need to be grounded coming out of the GDL 39 or did the software fixes remedy that? I have two devices needing GPS data, the GTR 200 and my FDS fuel flow gauge.

Hello Bugs,

While the GTR 200 doesn't need or use GPS data, it uses VHF Out data to provide you with frequency lists for hundreds of nearby and flight plan airports, so you will probably be selecting "Aviation In/NMEA & VHF Out" on the GDL 39 Pass Through Serial Format to enable this functionality.

If you are not using the White/Orange RX input on the GDL39, you should ground that wire.

Thanks,
Steve
 
Hello Bugs,

While the GTR 200 doesn't need or use GPS data, it uses VHF Out data to provide you with frequency lists for hundreds of nearby and flight plan airports, so you will probably be selecting "Aviation In/NMEA & VHF Out" on the GDL 39 Pass Through Serial Format to enable this functionality.

If you are not using the White/Orange RX input on the GDL39, you should ground that wire.

Thanks,
Steve

Thanks for the info. I finished my installation over weekend. The GDL 39 and GTR-200 are working correctly with GPS, however my FDS FC-10 fuel flow does not like the combo NMEA&VHF Out. It works fine with NMEA only but not with the combo mode. Not sure why. Not a big priority for me to get working but might contact FCS to see if they have a suggestion.

Overall very impressed with GTR-200! I do have one issue where my radio will display "Volume key is stuck". I have not figured out any rhyme or reason to what triggers this. It happens randomly, but all radio and intercom functions are working normally including the volume. Power cycle resolves usually, but may appear again randomly. The last flight it did not happen. I will try for a few more flights and see if happens again. Thanks for your help.
 
Check the baud rate on your Fuel computer. Typically NMEA/VHF is 9600 baud and just NMEA is 4800.
 
GDL 39 pass thru

I have a 696 (SWV6.9) GDL39 (SWV2.8) pass thru connected to a TT AP and a TT ADI works very intermittantly, most of the time neither the ADI or the AP will receive good pass thru info?? 696 is set to NMEA out and fast. Garmin tech said "that should work" it doesn't?? Should the yellow wire be grounded?? will the pass thru drive 2 devices simultaneously??
Dick
 
I have a 696 (SWV6.9) GDL39 (SWV2.8) pass thru connected to a TT AP and a TT ADI works very intermittantly, most of the time neither the ADI or the AP will receive good pass thru info?? 696 is set to NMEA out and fast. Garmin tech said "that should work" it doesn't?? Should the yellow wire be grounded?? will the pass thru drive 2 devices simultaneously??
Dick

Hello Dick,

The yellow wire is the 696 receive and should be connected to the green wire (TxA) on the GDL 39 bare wire cable. The yellow wire should not be grounded.

You should also ground the White/Orange wire on the GDL 39 bare wire cable if you are not using it.

An RS-232 output will generally be able to drive two devices, but it depends on those two devices. You might try connecting one at a time and determine if you really only have a problem when both are connected. You might also verify that those other devices are sharing the same power ground as the GDL 39.

Thanks,
Steve
 
orange/while still grounded

Hello Dick,

The yellow wire is the 696 receive and should be connected to the green wire (TxA) on the GDL 39 bare wire cable. The yellow wire should not be grounded.

You should also ground the White/Orange wire on the GDL 39 bare wire cable if you are not using it.

An RS-232 output will generally be able to drive two devices, but it depends on those two devices. You might try connecting one at a time and determine if you really only have a problem when both are connected. You might also verify that those other devices are sharing the same power ground as the GDL 39.

Thanks,
Steve

Steve, with the new software is it still best to ground the orange/white wire if no using it. My application will be to pass flight plan info from the 696 thru the gdl39 to my GRT system, the GRT then feeds the TT autopilot. Currently only one wire is used between the 696 and the GRT.
 
Steve, with the new software is it still best to ground the orange/white wire if no using it. My application will be to pass flight plan info from the 696 thru the gdl39 to my GRT system, the GRT then feeds the TT autopilot. Currently only one wire is used between the 696 and the GRT.

Hello Bill,

Yes, the guidance in the manual still recommends you ground the unused RxB White/Orange wire when not used.

You will be using the Orange TxB wire from the GDL 39 to provide data of the selected type to these external devices.

Thanks,
Steve
 
Thanks Steve

Got it, will let you know how the install goes.

As others have said, great to have access to you on VAF!
 
Bill, mine is wired as you said yours would be, daisy chaining the GDL39, 696 and autopilot eventually. I really like it. I remote mounted the GDL as well and just connected a spare transponder stub to it on the belly. Cleaner up on the glare shield. I also think Garmin should have stuck with the 696. Does it all and no fingerprints. Just me
 
Hmmm

I have been thinking about the remote mounting question. I did not want to do that because I hear you can use the GPS in the GDL39 to connect with your ipad even if using Foreflight (which I do). I think I still have the remote GPS puck from the 696 that was never used, wonder if that will work with the 39 so I could put in under the dash.

With that said, what can you tell me about the transponder antenna you used? Where did you mount the unit?




Bill, mine is wired as you said yours would be, daisy chaining the GDL39, 696 and autopilot eventually. I really like it. I remote mounted the GDL as well and just connected a spare transponder stub to it on the belly. Cleaner up on the glare shield. I also think Garmin should have stuck with the 696. Does it all and no fingerprints. Just me
 
I have been thinking about the remote mounting question. I did not want to do that because I hear you can use the GPS in the GDL39 to connect with your ipad even if using Foreflight (which I do). I think I still have the remote GPS puck from the 696 that was never used, wonder if that will work with the 39 so I could put in under the dash.

Bill,

Just to be clear, your 696 will provide GPS data to the GDL 39.

No GDL 39/39R connected to a Garmin Aera 5XX/7XX, GPSMAP 69X, or G3X/G3X Touch system needs a GPS antenna to be mounted remotely.

The GDL 39 will share GPS data with connected tablets/phones regardless of whether it is using its internal GPS receiver, or GPS data from a connected Garmin system.

Thanks,
Steve
 
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