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Van's Harness and the CAN Bus

Michael Burbidge

Well Known Member
I'm planning on a G3X Touch based avionics system. Many of the avionics and other devices, such as the magnetometer, AHRS, AP Servos sit on the CAN Bus.

The standard Van's Harness that ships with the RV-14 support both Garmin and Dynon. But I'm puzzled as to how it supports these Garmin devices that sit on the CAN bus.

As an example, the Van's wiring diagram has pins labeled "MAGNETOMETER/AHRS DATA A, B AND C". But the connectors, and connections don't appear to be CAN Bus compatible.

So I'm wondering if and how the standard Van's Harness supports the CAN Bus?

Thanks,
Michael-
 
One regret I have with my build is I should have called Aerotronics way earlier on to discuss my build. I did not buy the semi-outdated vans harness and in retrospect I wish I would have returned ALL the wiring that came with the kits. They charge a pretty penny for those wires and I ended up cutting out and replacing almost all of them. So do yourself a favor, call the avionics supplier who you plan on using and discuss in advance.
 
One regret I have with my build is I should have called Aerotronics way earlier on to discuss my build. I did not buy the semi-outdated vans harness and in retrospect I wish I would have returned ALL the wiring that came with the kits. They charge a pretty penny for those wires and I ended up cutting out and replacing almost all of them. So do yourself a favor, call the avionics supplier who you plan on using and discuss in advance.

Working with SteinAir, I had quite the opposite experience: I planned my avionics ahead of time and Stein slightly modified the fuselage harness (I ordered it from them as opposed to ordering from Vans) based on my planned panel, including the forward termination which would match up with panel when it was delivered. The wing and fuse harnesses worked just fine: I ended up adding a few wires for some minor mods / options added later, which I wove into the harnesses easily. I used the standard lighting (AeroLeds), pretty much all Garmin G3X touch avionics, and added optional servos/aileron trim/magnetometer mount etc - they all worked just fine with standard harnesses. I would have preferred twisted/shielded wiring for the lighting and would make that single change to the wing harnesses (based on magnetometer location) if I were building again, but no regrets.

In my case, the cost of harnesses was offset by time and effort saved, working with SteinAir and planning everything in advance. The panel arrived fully wired from SteinAir and the CAN bus was terminated so I can't precisely answer your question about that - it all just worked. The only wiring "issues" I had were minor things like identifying the correct wires in the supplied harness for mods that I made such as baggage area lighting, LED strip lighting, etc. A few clarification calls and emails (mostly because I'm not the best at reading wiring diagrams) with the guys at SteinAir took care of this.
 
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I guess since I replaced my lighting wires with shielded and I didnt use the gmu-22 (which is what the harness provides for) it was just easier and cleaner to run my own wires. Plus I removed all those **** molex connections and ran the wires straight to the panel.
 
G3X Touch Wiring Guidance

I'm planning on a G3X Touch based avionics system. Many of the avionics and other devices, such as the magnetometer, AHRS, AP Servos sit on the CAN Bus.

The standard Van's Harness that ships with the RV-14 support both Garmin and Dynon. But I'm puzzled as to how it supports these Garmin devices that sit on the CAN bus.

As an example, the Van's wiring diagram has pins labeled "MAGNETOMETER/AHRS DATA A, B AND C". But the connectors, and connections don't appear to be CAN Bus compatible.

So I'm wondering if and how the standard Van's Harness supports the CAN Bus?

Thanks,
Michael-

Michael,

Alongside the manufacturer of your original harness, we are always available to help decipher any wiring diagrams or confirm any pin assignments you are unsure of. Please feel free give us a call at 1-866-854-8433, 8-5 CT M-F, with any questions. In this case, it may be helpful to go ahead and email a copy of your wiring diagram over to us at [email protected] before calling, so we can take a look at your wiring guidance together.

Thanks,

Justin
 
The common fuselage harness saved me hours of work and was near perfect for my g3x system. The CAN bus must be terminated at both ends and is setup to do so at the roll and pitch servos with the common fuselage harness. From where the common fuselage d subs stick out behind the panel you create just a few feet of it with the nodes for whatever you decide to install. Very easy and was able to create the rest of the CAN bus in just a few hours.

The fuselage harness for me probably saved near 40 hours of work. Like everything else you can pay to speed up your build and get a professional harness or you can do it yourself.

If I were to build another -14 I would get the same common fuselage harness again and could probably wire the whole airplane and avionics in just a 2-3 days. The -14 is a really great kit that was designed to make the build go quick if you take advantage of the planning and prefabbed parts by Vans and others.
 
The common fuselage harness saved me hours of work and was near perfect for my g3x system. The CAN bus must be terminated at both ends and is setup to do so at the roll and pitch servos with the common fuselage harness. From where the common fuselage d subs stick out behind the panel you create just a few feet of it with the nodes for whatever you decide to install. Very easy and was able to create the rest of the CAN bus in just a few hours.

The fuselage harness for me probably saved near 40 hours of work. Like everything else you can pay to speed up your build and get a professional harness or you can do it yourself.

If I were to build another -14 I would get the same common fuselage harness again and could probably wire the whole airplane and avionics in just a 2-3 days. The -14 is a really great kit that was designed to make the build go quick if you take advantage of the planning and prefabbed parts by Vans and others.

The same ...
 
I had one of the first fuselage harnesses built to the Van's drawing and it worked fine with the CAN bus as did the wing harness to the roll servo. The GMU 11 was not out when I bought so the wiring would not have been able to accommodate it.

I found that the supplied harnesses were professionally done and worked well. Some have complained about having the forward and rear fuselage wiring split and I have complained about using the mini molex connectors which I feel are inappropriate for some uses in the aircraft.

All in all I would use them again as they were well worth the time saved.
 
Love it or hate it

Wow, seems like either you love it or hate it.

I don't want to change much from the standard Van's setup. Just wanted to understand how the CAN Bus works with it. Sounds like it does.

Michael-
 
I've worked on a couple of 14's with avionics and lighting problems, all of the issues were due to the Molex connector assy.
 
The fuselage harness that you buy with van's I found when researching is a generic catch all for most of the usual wiring setups that will be used by builders. Thus instead of saying, 'This is a canbus.... it goes from X to Y' is replaced with generics like 'Autopilot Data A' etc.

Technically you could house all of your garmin system in the panel and not have a canbus required unit anywhere in your fuselage. Of course that means no autopilot servos but still its completely possible.

For me my can bus will start in my right wing tip with my magnetometer, catch the roll servo on its the way back to the panel where most of its can bus friends will be. Once it winds its way through the radios, autopilot controller, various boxes and displays it heads down the fuselage to the tailcone where the other two auto pilot servos are and terminates there.
 
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