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Garmin GDL 39 will not connect to an autopilot?

pboyce

Active Member
I have a Garmin 696 which drives a Trutrak Digitrak autopilot. I would like to add the GDL 39 in order to get ADS-B weather and traffic. However the tech support person at Garmin said there is no way to add the GDL 39 to the 696 without losing the ability to drive an autopilot. Apparently it has something to do with the wires in/out. Now this seems very strange to me and not being an electrical expert I would like to ask if anyone can confirm or refute this? The tech support person at Trutrak looked at the GDL 39 manual and said it should work. So there is conflicting opinion on this.
 
I have a Garmin 696 which drives a Trutrak Digitrak autopilot. I would like to add the GDL 39 in order to get ADS-B weather and traffic. However the tech support person at Garmin said there is no way to add the GDL 39 to the 696 without losing the ability to drive an autopilot. Apparently it has something to do with the wires in/out. Now this seems very strange to me and not being an electrical expert I would like to ask if anyone can confirm or refute this? The tech support person at Trutrak looked at the GDL 39 manual and said it should work. So there is conflicting opinion on this.

That perhaps could be the case if you used the prefabricated "696 cable"(because it doesn't separate out the individual wires for use into an EFIS/AP, etc..), but if you use the "bare wire cable" then you should have no issues at all. It'll take a wee bit of re-wiring and user configuration, but should be fine! As I understand it from my brilliant Garmin engineering friends, the GDL basically adds a 2nd serial port to the 696 and passes the aformentioned info along.

This is going to take a few days to sort out each individual iteration of devices with the GDL, but I know Garmin is working on making most things work with it.

Cheers,
Stein
 
Hello pboyce,

Unfortunately the information you received from our product support was not entirely correct, for which I apologize... having only just received their first GDL 39 unit, they may still be working through the learning curve for this brand new device. The good news for you is that the GDL 39 has a second RS-232 port on it, which is intended for just this sort of application. So although you will lose the use of the single RS-232 port on the GPSmap 696 when you connect it to the GDL 39, you only need to connect the second RS-232 port on the GDL 39 to your NMEA-receiving device to continue using NMEA data. For further information, you can see pages 210-211 of the GPSmap 696 owner's manual (revision F).

thanks,
- Matt
 
Matt,

It was a pleasure to meet you in person this week. You and Steve deserve an award for spending all that time on your feet in that hot tent!

Do you have a link for the new 796 manual?

Thanks,

Brian C.
 
Don't have the answer but...

I bought a GDL 39 at OSH and hooked it up to my iPad. As I left OSH all I can say is WOW! The whole screen was just covered with targets. As we got further away, we could only spot about 1/5 the traffic within 5 miles of us that the ADS-B was showing us, and that is with it telling us where to look.

Can't wait until I get my RV done so I will have it on the panel.
 
Is it configurable to only see a certain range of targets or does it have default settings. For example, does it show ALL traffic at ALL altitudes or is it limited to 2-3 thousand feet? Programmable?
 
On the 796 you can filter altitude and on the traffic/map pages, you can control the scale of the page. If they are outside the scale, they don't show up.

I am sure the other displays have similar functions.

I zoomed out and had traffic targets showing that were 24 miles away.

You can touch a target and get tons of info about it.
 
ADS-B Traffic Altitude Filter

Is it configurable to only see a certain range of targets or does it have default settings. For example, does it show ALL traffic at ALL altitudes or is it limited to 2-3 thousand feet? Programmable?

As Brian correctly pointed out, the pilot can use the altitude filter to prevent traffic which is of little interest from showing up on the map and traffic page.

For example, the Unrestricted setting shows all traffic, but you will soon tire of seeing all those airliners up at 30,000'+ crossing in front of you on the map.

The Normal setting (traffic within +/- 2700 ft) seems to work well most of the time. If you are going to do a high vertical speed descent, you might want to choose BELOW to keep more traffic in sight below you.

While we don't yet have the Aera 79X Pilot Guide on the web, you can read all about the ADS-B traffic function starting on page 154 of the GPSMAP 69X Pilot Guide or on page 240 of the G3X Pilot Guide. The ADS-B traffic function is very similar for all the Garmin portables and for G3X.

ADS-B Traffic Pilot Selectable Altitude Filter Settings
  • NORMAL: Displays non-threat and proximity traffic from 2700 feet above the aircraft to 2700 feet below the aircraft. Typically used during enroute phase of flight.
  • ABOVE: Displays non-threat and proximity traffic from 9000 feet above the aircraft to 2700 feet below the aircraft. Typically used during climb phase of flight.
  • BELOW: Displays non-threat and proximity traffic from 2700 feet above the aircraft to 9000 feet below the aircraft. Typically used during descent phase of flight.
  • UNREST (unrestricted): All traffic is displayed.

This is my favorite G3X/GDL39 traffic screen shot from my trip out to Oshkosh. I couldn't see this aircraft at 11 nm descending straight at me on my course line, but I got an early heads up that it was there and I was able to keep clear of it.

TrafficOnCourse.jpg


Thanks to everyone who came by to visit us at the G3X tent at Oshkosh. It was great meeting so many of you that frequent this forum.

Thanks,
Steve
 
With the wiring described, 696 to GDL39 to Autopilot, if the GDL39 were to fail or lose power, would the connection between the 696 and Autopilot still work? In other words, is the GDL39 active or passive in passing the serial data from one serial port to the other?
 
With the wiring described, 696 to GDL39 to Autopilot, if the GDL39 were to fail or lose power, would the connection between the 696 and Autopilot still work? In other words, is the GDL39 active or passive in passing the serial data from one serial port to the other?

The GDL 39 must be powered and turned on for the second RS-232 port pass-through feature to function with the GPSmap 695/696 or aera 5xx units. (The aera 795/796 units have two RS-232 ports already, and the GDU37X displays have three RS-232 ports, so these products do not need or use this feature.)

- Matt
 
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GTX330 Upgrade

Matt, I have the GDL 39 connected to a 696. I just tried it out last night and love it. Way cool! Anyway, I also have a GTX330 transponder. I'm still a little foggy about all of this. What benefit would I get by upgrading my transponder to the ES for $1200? I also have a 430W that I can connect to the transponder for valid position reference. I think I read that I needed to do a free upgrade to the 430W to make it all work. And do I still need a connection between the GTX330 and 696 like I used to use for TIS? By the way, the TIS rarely worked in the Portland area which was supposed to have TIS service.
 
Matt, I have the GDL 39 connected to a 696. I just tried it out last night and love it. Way cool! Anyway, I also have a GTX330 transponder. I'm still a little foggy about all of this. What benefit would I get by upgrading my transponder to the ES for $1200? I also have a 430W that I can connect to the transponder for valid position reference. I think I read that I needed to do a free upgrade to the 430W to make it all work. And do I still need a connection between the GTX330 and 696 like I used to use for TIS? By the way, the TIS rarely worked in the Portland area which was supposed to have TIS service.

What you would get if you upgrade your 330 to ES is the ability to comply with the ADS-B out requirements of 2020. Also since you will then be capable of sending the ADS-B out signal, your transponder will wake up the ground stations and they will send back the composite TIS-B signal that your GDL-39 can receive.

The 430W can serve as a position source for the transponder today it just won't be ready for 2020 until they come out with the new firmware. If you have version 3.2, that is the current release available to the masses.

If you connect the GDL-39 to the 696, you won't be able to connect the 330 to the 696. The pass though feature of the GDL-39 currently only supports NMEA data.

If you upgrade your 330 to ES and connect the 430W to the xponder, your GDL-39 will end up giving you full air to air and TIS-B based traffic on your 696 and it should be many times better than the older TIS traffic you are familiar with. With that setup, if you are in the reception area of a ground station, you will see the same traffic that the controllers do on their screens.
 
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No pass through of radio frequencies...

The biggest issue I have with the GDL39 and my 696 is losing the radio frequency tuning feature... I was ready to buy until that detail was revealed...
 
The biggest issue I have with the GDL39 and my 696 is losing the radio frequency tuning feature... I was ready to buy until that detail was revealed...

Have no fear... although the current firmware version supports NMEA data only, a near-future software update will add the ability to pass through other RS-232 formats, including Aviation, SL30/40 radio tuning, etc.

- Matt
 
The biggest issue I have with the GDL39 and my 696 is losing the radio frequency tuning feature... I was ready to buy until that detail was revealed...

Can't speak for Garmin but I bet we will see that functionality expanded for the 696 soon.


Edit:

Matt beat me to it....
 
What you would get if you upgrade your 330 to ES is the ability to comply with the ADS-B out requirements of 2020. Also since you will then be capable of sending the ADS-B out signal, your transponder will wake up the ground stations and they will send back the composite TIS-B signal that your GDL-39 can receive.

The 430W can serve as a position source for the transponder today it just won't be ready for 2020 until they come out with the new firmware. If you have version 3.2, that is the current release available to the masses.

If you connect the GDL-39 to the 696, you won't be able to connect the 330 to the 696. The pass though feature of the GDL-39 currently only supports NMEA data.

If you upgrade your 330 to ES and connect the 430W to the xponder, your GDL-39 will end up giving you full air to air and TIS-B based traffic on your 696 and it should be many times better than the older TIS traffic you are familiar with. With that setup, if you are in the reception area of a ground station, you will see the same traffic that the controllers do on their screens.

Thanks for the good info Brantel. I think it's starting to become clearer now. I was trying to figure out if it would be worth spending the money to upgrade the 330 transponder right now or a few years down the road. It sounds like it may be a good thing to do now.

When I was testing it last night I'm sure there was some traffic out there I wasn't picking up that I could hear on the radio. It was probably below radar coverage. So perhaps the transponder upgrade would help with that. I wonder if when I fly with friends who don't have ADS-B out and I do, that it may provide more targets for them on their GDL-39? When I turned on unlimited traffic it was cool to see an airplane fly over the top of me at over thirty thousand feet with flight number indcated.

I installed the Garmin app on my iPhone as a trial. I'm very impressed with that program. The really cool thing is that I have the 696 wired to the GDL-39 and the iPhone would receive the signal from the GDL-39 via Bluetooth at the same time. So I could leave the radar screen up full time on the iPhone which makes it easier to see targets on verses on the 696 map page. Very nice and may decide to let my Foreflight subscription lapse and go with Garmin's app. Also, since the GDL-39 has a built in GPS there's no need for a GPS to drive the iPhone/iPad. Extra bonus.

I was also impressed with how the 696 now displays weather at all the nearest airports. Maybe XM did that before and I didn't notice. There are several nice upgrades with the new 696 software.

Another nice feature is the ability to display the location of the ground stations. I found out there is actually a ground station right at my airport. After I taxied to my hanger I actually had two good ground station signals on the ground. When flying I think I had about five of them. Coverage with ground stations seems to be very good in my area.

The weather functions worked great and my XM subscription is going away. I turned it off for my testing and didn't miss any features so far. I'm very impressed so far.
 
TFR's Work

One last bit of info regarding the GDL-39. When I departed my airport last night I immediately saw a yellow TFR circle around Hillsboro, about 10 miles away. That's because they are having an airshow this weekend and there are airport closures. Using the cursor on the 696 I was able to select the TFR and get all the details. So I can confirm that the TFR function of the GDL-39 works well. I'm assuming the TFR circle will be turning red when active.
 
I put a report of my first experience using the GDL 39 with my Aera 510 on my regular hangout:
http://www.supercub.org/forum/showthread.php?43124-New-Garmin-GDL-39-XM-WX-killer

One question I have is how to use the "second serial port" of the GDL 39? I have a fuel flow gauge that takes GPS data but had to disconnect because the new harness only has the connector for the GDL 39. Before I start splicing into my new harness, would like to know how the second serial port is used. I don't see a second connector on the GDL. Also, is there a revised manual for the Aero 5xx series with the new features? Thanks!
 
One question I have is how to use the "second serial port" of the GDL 39? I have a fuel flow gauge that takes GPS data but had to disconnect because the new harness only has the connector for the GDL 39. Before I start splicing into my new harness, would like to know how the second serial port is used. I don't see a second connector on the GDL. Also, is there a revised manual for the Aero 5xx series with the new features? Thanks!

Hello Bugs,

To use the second serial port in a semi-permanently-wired installation of this type, you will need the GDL 39 Bare Wire Power/Data Cable (part number 010-11686-40). Many dealers will include this cable with the GDL 39 (in place of the standard GDL 39 cable that connects directly to a GPS unit) if you tell them in advance how you plan to hook it up.

Take a look at pages 3-5 and 3-6 of the the GDL 39 User's Guide to see how it is connected. In your case, you will connect the TxA (green) and RxA (white/green) wires on the GDL 39 cable to the RS-232 RX (yellow) and TX (blue) wires on your existing aera 5xx cable, and connect the GDL 39's TxB (orange) wire to wherever the TX (blue) wire on your aera 5xx was previously connected. Don't forget to hook up power and ground, of course.

I'm told that a updated aera 5xx manual will be forthcoming soon. In the meantime, you can use Appendix D in the current version of the pilot's guide to reference the wiring colors for your existing cable harness.

- Matt
 
Thanks Matt. Since I already have the cable for Aera 500, I think I will splice into mine and put a serial out pigtail. I assume the orange and orange/white wires are in there to tap into?
 
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Thanks Matt. Since I already have the cable for Aera 500, I think I will splice into mine and put a serial out pigtail. I assume the orange and orange/white wires are in there to tap into?

Don't assume they are. I cut open a pre-made Garmin cable once to get at some wires that I assumed would be in there. They were not.....
 
GDL-39 to Autopilot Issue

G3Xpert Steve,

I have more questions for you. I connected the GDL as a permanent installation yesterday but can't get the serial port B to drive my autopilot. I wired it all up with the hardwire cable and all the ADS-B stuff works. I then took the serial port B from the GDL to where the 696 used to connect to autopilot with no luck. I even tried reversing polarity. If I connect serial port A from the GDL in parallel it will work fine if I change the 696 output to Nema. Of course then the Wx and traffic no longer works. Previously I had the serial port on the 696 connected to the Trio autopilot, 330 transponder, ADI and ELT. Lots of connections but it seemed to work fine. Really the only thing I could disconnect would be the 330 since I'm not using the TIS any longer. So is there anything else I need to do with the GDL to configure it for Nema and make it work with my autopilot and other devices?

I also have a 430W in my panel. I currently have it connected via ARNIC to the 330. If I upgrade the 330 to ES am I all set with the GPS signal to the 330 to make it work correctly?

Thanks,

Mark
 
G3Xpert Steve,

I have more questions for you. I connected the GDL as a permanent installation yesterday but can't get the serial port B to drive my autopilot. I wired it all up with the hardwire cable and all the ADS-B stuff works. I then took the serial port B from the GDL to where the 696 used to connect to autopilot with no luck. I even tried reversing polarity. If I connect serial port A from the GDL in parallel it will work fine if I change the 696 output to Nema. Of course then the Wx and traffic no longer works. Previously I had the serial port on the 696 connected to the Trio autopilot, 330 transponder, ADI and ELT. Lots of connections but it seemed to work fine. Really the only thing I could disconnect would be the 330 since I'm not using the TIS any longer. So is there anything else I need to do with the GDL to configure it for Nema and make it work with my autopilot and other devices?

I also have a 430W in my panel. I currently have it connected via ARNIC to the 330. If I upgrade the 330 to ES am I all set with the GPS signal to the 330 to make it work correctly?

Thanks,

Mark

Hello Mark,

First, I tried to respond to your private message yesterday, but your message box was full. We recently disabled our private message support on VAF because of the limitations of private messaging and because it is generally easier for us to provide support via the [email protected] inbox (or respond to postings like this).

Did you try connecting just 1 of the serial devices to the orange wire coming out of the GDL39? It would be good to return to basics and establish that the GDL39 port B output is indeed working. As you probably know, RS-232 is a point-to-point interface and not guaranteed to work with more than one connected device, but we recognize that many are doing this and it generally works.

Also, did you try both of the configurable speed choices on the GDL39 output?

We know you already have a 696 and it is a great unit if you need a portable, but something else to consider given this installation. It is pretty common for many of us to purchase a GPSMAP 696, mount it in a panel, then connect a handful of RS-232 devices to the single serial output. The GDU 375 is designed to be panel mounted, has a front mounted SD card slot, and has 3 serial ports instead of 1.

With a GDU 375 you can connect a GDL39 to one of the serial ports, still have 2 free serial ports for connecting other devices, and not be dependent on the GDL39 to forward data to your other RS-232 devices. Just something for those reading this to keep in mind.

With regard to your last question, the answer is Yes. As mentioned in other posts, the software in the GTX330 and GNS430W will require updating later this year to be fully "V2" ADS-B compliant for 2020, but you will immediately receive the benefits of ADS-B traffic and weather with the current "V1" software if you upgrade to add "ES". You could either wait on your "ES" upgrade until the "V2" software is available, or get the "ES" upgrade now and upgrade the software to be fully V2 compliant later this year. Those of us currently using V1 software with GTX330ES or GTX23ES extended squitter transponders can certainly vouch for the vastly improved traffic support you will receive from that upgrade.

Let us know if you have additional questions.

Thanks,
Steve
 
Hello Mark,

First, I tried to respond to your private message yesterday, but your message box was full. We recently disabled our private message support on VAF because of the limitations of private messaging and because it is generally easier for us to provide support via the [email protected] inbox (or respond to postings like this).

Did you try connecting just 1 of the serial devices to the orange wire coming out of the GDL39? It would be good to return to basics and establish that the GDL39 port B output is indeed working. As you probably know, RS-232 is a point-to-point interface and not guaranteed to work with more than one connected device, but we recognize that many are doing this and it generally works.

Also, did you try both of the configurable speed choices on the GDL39 output?

We know you already have a 696 and it is a great unit if you need a portable, but something else to consider given this installation. It is pretty common for many of us to purchase a GPSMAP 696, mount it in a panel, then connect a handful of RS-232 devices to the single serial output. The GDU 375 is designed to be panel mounted, has a front mounted SD card slot, and has 3 serial ports instead of 1.

With a GDU 375 you can connect a GDL39 to one of the serial ports, still have 2 free serial ports for connecting other devices, and not be dependent on the GDL39 to forward data to your other RS-232 devices. Just something for those reading this to keep in mind.

With regard to your last question, the answer is Yes. As mentioned in other posts, the software in the GTX330 and GNS430W will require updating later this year to be fully "V2" ADS-B compliant for 2020, but you will immediately receive the benefits of ADS-B traffic and weather with the current "V1" software if you upgrade to add "ES". You could either wait on your "ES" upgrade until the "V2" software is available, or get the "ES" upgrade now and upgrade the software to be fully V2 compliant later this year. Those of us currently using V1 software with GTX330ES or GTX23ES extended squitter transponders can certainly vouch for the vastly improved traffic support you will receive from that upgrade.

Let us know if you have additional questions.

Thanks,
Steve


Steve,

Thanks for the reply. I noticed after I cleaned my mailbox that yours went to private and posted here. Probably a good group discussion anyway.

I have not tried Port B on a single device. I was hoping it would work since Port A would drive all the devices fine when 696 set to Nema. Of course at this point I have to lay on my back and figure out how to gain access to a rats nest of wiring. Perhaps I can just pull plugs on other units for test. So I'll give that a try tonight and let you know the results. I was hoping for a simple answer like a setting I may have missed but it doesn't look like it.

I would love to have a GDU-375 but unfortunately it didn't come out until after I installed my 696.

We are going to the open house at the Garmin factory in Salem on Thursday afternoon for their open house so I can talk to the guys there about the 330 upgrade. Thanks for the info.

Mark
 
For years I have flown with the GPSMAP 696 driving a Trutrak autopilot. Worked great. Now with the GDL 39 connected to the 696 (and getting great free weather!) I cannot get the autopilot to work properly.

I connected the orange wire from the GDL 39 bare wire harness to my Trutrak autopilot, updated the firmware of the 696 to v6.1 and still no luck with getting the autopilot to work. Frank from Garmin technical support said he will look into it further and let me know tomorrow what the problem is. I'm not an electrical engineer but it appears to me that the GDL 39 is not passing thru NMEA data to the autopilot. Hopefully a new firmware update will fix this situation.
 
status of additional comm data?

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)?
 
For years I have flown with the GPSMAP 696 driving a Trutrak autopilot. Worked great. Now with the GDL 39 connected to the 696 (and getting great free weather!) I cannot get the autopilot to work properly.

I connected the orange wire from the GDL 39 bare wire harness to my Trutrak autopilot, updated the firmware of the 696 to v6.1 and still no luck with getting the autopilot to work. Frank from Garmin technical support said he will look into it further and let me know tomorrow what the problem is. I'm not an electrical engineer but it appears to me that the GDL 39 is not passing thru NMEA data to the autopilot. Hopefully a new firmware update will fix this situation.

Hello Pboyce,

Sorry that you and Mark are having trouble. Thanks for letting us know.

We suspected the GDL39 output might not have tolerated the triple loads in Mark's installation, but now that you are also reporting problems using port B on the GDL39 with just a single external device, we are going to re-test this in the morning and make sure everything looks ok.

Since NMEA Out is ASCII, it is easy to connect the GDL39 output to a PC serial port and see the data in a terminal program. We have to make sure there is a common data ground reference between the GDL39 and any receiving device (we can't just connect the orange wire), but I am sure you are already doing this with your autopilot and GDL39.

We will test both of the selectable speeds for this port and report back.

Thanks,
Steve
 
I put a report of my first experience using the GDL 39 with my Aera 510 on my regular hangout:
http://www.supercub.org/forum/showthread.php?43124-New-Garmin-GDL-39-XM-WX-killer

One question I have is how to use the "second serial port" of the GDL 39? I have a fuel flow gauge that takes GPS data but had to disconnect because the new harness only has the connector for the GDL 39. Before I start splicing into my new harness, would like to know how the second serial port is used. I don't see a second connector on the GDL. Also, is there a revised manual for the Aero 5xx series with the new features? Thanks!

we just used our aera 500/GDL39 today and is blows me away. I owned a Slyradar and the GDL is far superior. It recieves stations 200 nm away and has all weather.
 
Steve, here is a suggestion for those of us that cannot physically test the NMEA output on the orange wire--serial ports on computers are very rare these days, plus I own a macbook! On the WX>Info page for the GDL 39, you could put a line there to indicate whether data is being transmitted on the orange wire. That would make diagnosis for this difficult issue that much easier. Just a thought.
 
Still not working

Steve,

I spent a couple more hours on this tonight with no luck. I rechecked wiring and removed connectors from all devices except Trio autopilot. Still no signal on wires that used to connect to 696. I have toggle switch to select whether 696 or 430W drives autopilot. The 430W still operates it fine. Although, as you probably know, you have to have a waypoint entered in 430W to provide valid signal for autopilot to work. That was never the case with the 696 before. Perhaps GDL is missing the same data the 430W doesn't have when no waypoint selected. Just a thought. I tried 696 with and without waypoint but it didn't matter. I also tried normal and fast baud.

I'll be at Garmin Salem factory tomorrow afternoon. Any chance they'd have one that works on bench to swap as test.

Thanks,

Mark
 
Steve,

By the way, there's a typo in the manual if you didn't already know. The A & B port labels are reversed on the pass through wiring diagram compared to the previous page. The wire colors are still okay though.
 
Probably unrelated but I thought I would mention something with the 696 that can be a issue.
When you select TIS in and NMEA out you also get VHF out on the 696. VHF out requires 9600 baud so regardless of what you have set prior in the NMEA out mode the garmin unit shifts to 9600 baud for NMEA out also. You can not change this output as long as you have TIS in selected. The baud is not user selectable however appears to be. Resetting the TruTrac autopilot for 9600 baud in my case fixed the issue I was having with the autopilot losing the signal after I added traffic to the 696 display.

George
 
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We tested a GPSMAP 696 bare wire setup this morning using V6.10 software with several GDL39 units using both V2.20 and V2.30 software. The goal of this testing was to identify any conditions which might impact supplying data to external devices.

While we have not been able to consistently reproduce a problem with the GDL39 serial output, we have seen cases where the output is incorrect. We have also noted that the problem occurs more frequently when using the Normal setting than with the Fast setting. We have never observed a case where there was no data being output.

We have not completed this investigation, but we wanted to assure our customers that we are making some progress and will do everything possible to resolve any identified issues quickly.

It is important to understand that only the GPSMAP 69X and Aera 5XX products use this port forwarding feature of the GDL39. G3X, GDU 37X and Aera 7XX installations are NOT impacted. Only those GPSMAP 69X and Aera 5XX installations which rely on the port forwarding feature of the GDL39 to supply data to external devices are potentially impacted.

In all cases, the traffic and weather features provided by the GDL39 are working as designed.

We appreciate your patience and help in resolving this issue.

Thanks,
Steve
 
Steve,

Thanks for your continued help with this. In my case the Trio autopilot manual indicates that it accepts either NMEA 0183, V2.XX stream format or Aviation Link format. Perhaps that is standard but I thought I'd throw that out there in case it is unique to Trio. And to correct what I said previously, I don't actually know if I have data out or not, as I don't have any way to view that. The autopilot simply doesn't recognize it. I did upgrade the GDL firmware to the latest version last night as well with no change. That is really cool how you can update the firmware using the iPhone though.

Otherwise I'm very happy with the performance of the GDL. With an external antenna at 3000 feet near PDX I'm getting (7) ground stations and up to 190 miles away. I'm sure it would be even better if I went higher. The external antenna really works great as I am getting twice the stations of a friend with the unit mounted antenna inside the airplane.
 
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We tested a GPSMAP 696 bare wire setup this morning using V6.10 software with several GDL39 units using both V2.20 and V2.30 software. The goal of this testing was to identify any conditions which might impact supplying data to external devices.

While we have not been able to consistently reproduce a problem with the GDL39 serial output, we have seen cases where the output is incorrect. We have also noted that the problem occurs more frequently when using the Normal setting than with the Fast setting. We have never observed a case where there was no data being output.

We have not completed this investigation, but we wanted to assure our customers that we are making some progress and will do everything possible to resolve any identified issues quickly.

It is important to understand that only the GPSMAP 69X and Aera 5XX products use this port forwarding feature of the GDL39. G3X, GDU 37X and Aera 7XX installations are NOT impacted. Only those GPSMAP 69X and Aera 5XX installations which rely on the port forwarding feature of the GDL39 to supply data to external devices are potentially impacted.

In all cases, the traffic and weather features provided by the GDL39 are working as designed.

We appreciate your patience and help in resolving this issue.

We have some additional information to share regarding our investigation of this issue.

We have identified that data coupling can occur, in some cases, between the Port A and Port B wire pairs in the 60 inch long GDL39 bare wire cable. Since the Port B orange/white wire is currently unused and floating in most installations, it is susceptible to coupling noise into the Port B receiver which appears to be the source of the problem.

We may eventually make software changes to make the system more tolerant of this type of installation, but for now we recommend that anyone using the bare wire cable ground the orange/white wire to the black ground wire (which should already be grounded).

We also recommend that the NMEA Out setting on the GPSMAP 69X and Aera 5XX (these are the only devices which use port forwarding) be set to FAST, not NORMAL.

Please send us an email if you have any questions.

Thanks,
Steve
 
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Steve, I connected the white/orange wire to ground and still no luck in getting the Trutrak autopilot to work. Weather, however, still remains great. Let's hope to hear if Mark and his Trio AP had any luck.
 
Just an FYI, on the Dynon systems, the NMEA needs to be set to normal. Fast leaves something out that Dynon needs.

Not sure if this applies to TT or Trio.
 
Steve, I connected the white/orange wire to ground and still no luck in getting the Trutrak autopilot to work. Weather, however, still remains great. Let's hope to hear if Mark and his Trio AP had any luck.

Hello Pboyce,

You probably already checked this, but is the autopilot listening at 4800 baud?

If we need to I can capture an output file and provide it to TT to evaluate, but the data should be the same data that your 696 was transmitting before the GDL39 was connected.

Thanks,
Steve
 
Yes, the Trutrak AP was set to 4800 and the output on the 696 was set to 'Fast'. I think your idea to provide a file to Trutrak is a good one. They are a great company with great products. There is only a handful of companies that provide for 95% of the standalone autopilots, so it is smart to check in with them to make sure the data format is what they need.
 
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Yes, the Trutrak AP was set to 4800 and the output on the 696 was set to 'Fast'. I think your idea to provide a file to Trutrak is a good one. They are a great company with great products. There is only a handful of companies that provide for 95% of the standalone autopilots, so it is smart to check in with them to make sure the data format is what they need.

Hello Pboyce,

Thanks. We have been discussing this with TruTrak this afternoon.

Our autopilots have come back from Oshkosh and we are working to get them unpacked and on our benches so we can do some testing. We have both Trio GX Pro and TruTrak GX Pilot autopilots to test with.

While we normally drive them directly from a G3X display serial port, we will connect them to portables through the GDL39 and see what we can learn.

Thanks,
Steve
 
Working on it now...

I have a GDL 39 in my hands and now have the bare wire cable so that I can wire it all into the autopilot (just got the bare wire cable in today)...hopefully I don't actually need the GDL-39 to be receiving anything to test it, or it looks like I will have to fly half way to KC to test it tomorrow! Any good lunch places between here and KC? :)

I will let you know as soon as we get something going here, which should be tomorrow.

Sorry for the delay on this one guys...
 
Yes, the Trutrak AP was set to 4800 and the output on the 696 was set to 'Fast'. I think your idea to provide a file to Trutrak is a good one. They are a great company with great products. There is only a handful of companies that provide for 95% of the standalone autopilots, so it is smart to check in with them to make sure the data format is what they need.


Just to possibly save you time as I posted earlier in this thread if you have TIS in enabled on the 696 your NMEA baud output is 9600 regardless of what you have set in the 696. I went through this exact problem in getting my autopilot to work after adding traffic to the 696. Might help or might not but try setting your autopilot to 9600 baud. Here is the paragraph from the 696 manual. When you set it up in the unit its not clear at all that the unit switches the NMEA output to 9600 baud even though you have 4800 selected.

TIS In/NMEA & VHF Out—receives TIS data and transmits out both NMEA data, at
9600 baud, and VHF frequency tuning information to a Garmin Nav/Comm

George
 
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We have some additional information to share regarding our investigation of this issue.

We have identified that data coupling can occur, in some cases, between the Port A and Port B wire pairs in the 60 inch long GDL39 bare wire cable. Since the Port B orange/white wire is currently unused and floating in most installations, it is susceptible to coupling noise into the Port B receiver which appears to be the source of the problem.

We may eventually make software changes to make the system more tolerant of this type of installation, but for now we recommend that anyone using the bare wire cable ground the orange/white wire to the black ground wire (which should already be grounded).

We also recommend that the NMEA Out setting on the GPSMAP 69X and Aera 5XX (these are the only devices which use port forwarding) be set to FAST, not NORMAL.

Please send us an email if you have any questions.

Thanks,
Steve

Steve,

I have not had a chance to ground the unused wire yet to check for the data coupling issue. Although I did speak with the guys at Garmin Salem this afternoon and they said that there was no need to try that. That's because I still have the 330 connected to that serial port for the TIS function. Since the 330 is transmitting data on that line it would not be floating in my case.

I confirmed with Trio today that either 4800 or 9600 will work with the Pro Pilot. I've tried both. You may be hearing from Jerry from Trio as he also wants to make sure the GDL will work with their autopilots.

We look forward to hearing what you find during further testing. Let me know if you need anything tested in the field. I should have an old laptop with a serial port if it would do any good to check for data out using a terminal program and verify that my GDL is actually working on port B.

One last thing I'm confused about after talking to one of the guys in Salem. Does my 330 need to go back to your place in Kansas for a hardware upgrade to ES or is it a simple software upgrade I can get from a local Garmin dealer?

By the way, great traffic coverage flying into Salem today since the system was being triggered by a local ADS-B out signal. Hmm, maybe from the Garmin building. Also it was amazing how the airplane I was flying right next to magically disappered from the screen after leaving Salem and flying beyond 15 miles. Good reason to upgrade 330 to ES.

Thanks,

Mark
 
GDL39 Autopilot Testing

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.

Thanks,
Steve

Trio autopilot operating with GDL39 output.
IMAG0168.jpg


GPSMAP 696 configuration during test.
20120817_071951.jpg
 
Steve, your 696 interface screen shows GDL39 'Pass-through serial format' as a selectable item. My screen does not show that. Do I have the same software as you? I'm using v6.1 on the 696 and v2.2 on the GDL39.
 
Steve, your 696 interface screen shows GDL39 'Pass-through serial format' as a selectable item. My screen does not show that. Do I have the same software as you? I'm using v6.1 on the 696 and v2.2 on the GDL39.

Pboyce,

Yes, you caught a glimpse of our newer software (still in development) which expands the port forwarding to include all of our previously supported In/Out formats (Stephen asked about this in an earlier post). We also tested V6.10 software this morning (see screen below) and it works just as well.

I also wanted to mention that the Trio autopilot also indicates "No GPS" anytime you are not navigating. Make sure and activate a flight plan or a direct to or you will not know if your GDL39 interface is working or not.

Thanks,
Steve

20120817_083823.jpg
 
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Steve (or anyone),
Can the GDL-39 output NMEA data from its internal GPS without being connected to a 696? What I've read suggests that the serial out only functions when a 696 connection is present. Since I don't own a 696, I'm hoping that I can purchase a GDL-39 still output the NMEA data via the bare data cable. Thanks, Steve
 
Steve (or anyone),
Can the GDL-39 output NMEA data from its internal GPS without being connected to a 696? What I've read suggests that the serial out only functions when a 696 connection is present. Since I don't own a 696, I'm hoping that I can purchase a GDL-39 still output the NMEA data via the bare data cable. Thanks, Steve

Steve.

Sorry, the GDL39 will not output NMEA data on its own without a portable GPS providing that data.

It will, of course, provide GPS data to an iPad or Android device when using Garmin Pilot on those devices.

Thanks,
Steve
 
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