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Decision: Garmin or Dynon

Dynon IFR

When doing my initial system configuration designs for both Garmin and Dynon wish list I looked at the installation documentation quality and detail. Garmin was detailed and professional and what would be expected for a TSO?d system. Dynon mostly adequate but lacking in detail about interface definitions -particularly the GP and EGP interfaces for the EMS-220. Calling Dynon and asking for the interface characteristics in two port format or equivalent circuit format got nowhere with the tech support guys and they wouldn?t refer me to their engineering department. The Garmin documentation has the necessary information in the TSO?d version of the documentation. Additionally, and more importantly the Dynon system architecture has a number of single point failures for a two display system. They may be unlikely failures but they are built into the system architecture and impossible to work around unless you build two completely separate display systems isolated from each other. Two examples - GPS- 2020 - HDX requires both displays to be tied to the same GPS - putting a second GPS - 2020 or the older GPS-250 on the second display is not permitted and will result in system malfunction according to Dynon Tech support. The other significant single point failure is in the ADAHRS primary and secondary being tied through the same bus connection. A shorted bus line or babbling bus from one ADAHRS will result in loss of ADAHRS data to both displays. These failures may be unlikely but they would result in loss of important data during IFR flight for a single failure. I haven't looked at the Garmin system in enough detail to convince myself that there are no single point failures that would be as significant in IMC flight. I would be suprised if there were - but I dont know for sure. So- if you are putting together a configuration for serious IFR Dynon is probably not the answer.
KT
 
Please buy both Dynon and GRT. Competition is great and if it wasn't for all the great folks buying Dynon and GRT, I wouldn't be able to buy my Garmin avionics at these prices. If no one bought the other brands then Garmin could charge whatever they wanted. So please keep buying the other brands :D Just don't ask me why I have nothing but Garmin in my panel :rolleyes:;)
 
When doing my initial system configuration designs for both Garmin and Dynon wish list I looked at the installation documentation quality and detail. Garmin was detailed and professional and what would be expected for a TSO?d system. Dynon mostly adequate but lacking in detail about interface definitions -particularly the GP and EGP interfaces for the EMS-220. Calling Dynon and asking for the interface characteristics in two port format or equivalent circuit format got nowhere with the tech support guys and they wouldn?t refer me to their engineering department. The Garmin documentation has the necessary information in the TSO?d version of the documentation. Additionally, and more importantly the Dynon system architecture has a number of single point failures for a two display system. They may be unlikely failures but they are built into the system architecture and impossible to work around unless you build two completely separate display systems isolated from each other. Two examples - GPS- 2020 - HDX requires both displays to be tied to the same GPS - putting a second GPS - 2020 or the older GPS-250 on the second display is not permitted and will result in system malfunction according to Dynon Tech support. The other significant single point failure is in the ADAHRS primary and secondary being tied through the same bus connection. A shorted bus line or babbling bus from one ADAHRS will result in loss of ADAHRS data to both displays. These failures may be unlikely but they would result in loss of important data during IFR flight for a single failure. I haven't looked at the Garmin system in enough detail to convince myself that there are no single point failures that would be as significant in IMC flight. I would be suprised if there were - but I dont know for sure. So- if you are putting together a configuration for serious IFR Dynon is probably not the answer.
KT

I'm going to have to disagree with you. As you mentioned, those failures are very unlikely. Second, you shouldn't, and can't legally, rely on just Dynon for an IFR platform. Those risks you mentioned are in my mind totally mitigated by backups. A G5 or D10 for backup attitude, airspeed, heading, etc. and a GPS navigator (that uses its own antenna) for the rest.
 
Service

I can't speak for Garmin, but for me, the service and responsiveness of the people at Dynon has been absolutely first class.

Cheers,
Ackselle
 
I wonder if this is possible with the RV-12iS given that if you order a single-panel system, you will get a single-panel wiring harness kit. Maybe you can ask to upgrade the wiring without the actual second screen? But I can't imagine it being that much work to add a second screen and wiring later, can it?

There is only one wiring harness at least for the Garmin harness. I had order a single panel PFD (GDU460) and later on added the MFD (GDU460). It?s plug and play. The only thing you will need will be the new MFD panel cut out and a reinforcement bracket.
 
There is only one wiring harness at least for the Garmin harness. I had order a single panel PFD (GDU460) and later on added the MFD (GDU460). It?s plug and play. The only thing you will need will be the new MFD panel cut out and a reinforcement bracket.

Perfect, thanks!
 
Skyview is a fully redundant system

GPS- 2020 - HDX requires both displays to be tied to the same GPS - putting a second GPS - 2020 or the older GPS-250 on the second display is not permitted and will result in system malfunction according to Dynon Tech support.
You should connect the GPS-2020 (POS1) to both display serial 5 and the GPS-250 to both display serial 3 for instance. You can then select which serial is your reference POS if your GPS-2020 is failing.

The other significant single point failure is in the ADAHRS primary and secondary being tied through the same bus connection. A shorted bus line or babbling bus from one ADAHRS will result in loss of ADAHRS data to both displays.
The Skyview bus has built-in redundancy (4 wires instead of 2).
If you want more than full redundancy, you connect ADAHRS primary to HDX 1 via DB9 top and ADAHRS secondary to HDX 2 via DB9 top. Both DB9 bottom of the HDX are interconnected together via a HUB and to other peripherals like EMS, AP servos.
 
You should connect the GPS-2020 (POS1) to both display serial 5 and the GPS-250 to both display serial 3 for instance. You can then select which serial is your reference POS if your GPS-2020 is failing.


The Skyview bus has built-in redundancy (4 wires instead of 2).
If you want more than full redundancy, you connect ADAHRS primary to HDX 1 via DB9 top and ADAHRS secondary to HDX 2 via DB9 top. Both DB9 bottom of the HDX are interconnected together via a HUB and to other peripherals like EMS, AP servos.

Indeed you can use two separate serial inputs for two GPS Receivers but that then only leaves three for all other serial inputs. Transponder, ADSB in and non Dynon radio (GTR 200) leaves nothing for a second radio (GNC 255) in my template system. Why anyone would design a system architecture that required the serial inputs to each display to be hard wired together when there is a RS232 and ethernet bus between units is beyond a novelty. If it had been done right there would be 10 serial inputs available.
If as you say, the HDX top network bus connectors are a separate network from the bottom HDX network connectors that would mitigate the concern about single point failures in the ADAHRS interfaces. The network hub connectors are hardwired through circuit board traces with no electronic interfaces in the hub that I could detect without taking one apart. I will go through the documentation again to see if you are right about the separation of the two HDX network connectors. Would remove the need for a separate backup unit for basic instruments.

KT
 
HDX network connectors

?Each SkyView display has two SkyView Network connections on the back. In the event of a failure of a SkyView display, the two SkyView Network connectors are ?electrically common?; even if the SkyView display is failed or powered off, all pins of the upper connector are electrically connected to all pins of the lower connector.? From page 21-6 of the Dynon installation manual. So there is just one network bus for the complete system and depending on the exact configuration of the databus may be subject to a single point failure that takes down the whole system. Even if the probability of all the internal system component failures that can result in a databus failure is very small this is still a single point first failure that can result in loss of primary instruments. So even with a dual display system there is the high probability of the need to have a basic backup independent capability to avoid that single point failure.

KT
 
I'm going to have to disagree with you. As you mentioned, those failures are very unlikely. Second, you shouldn't, and can't legally, rely on just Dynon for an IFR platform. Those risks you mentioned are in my mind totally mitigated by backups. A G5 or D10 for backup attitude, airspeed, heading, etc. and a GPS navigator (that uses its own antenna) for the rest.

To be legal for IFR you need a TSO?d GPS navigator or an approved ILS/VOR capability. The GNC 255 is TSO?d and was part of my template system. It doesn?t allow you to file ?direct? but you can go direct if there is radar vector coverage and you get the clearance and there is a VOR or ILS at the destination and alternate. Poor mans IFR. The point is that having a second HDX display and the alternate ADAHRS installed may be good for many of the failure modes of the Dynon system but a separate backup D10 or similar is required if you want to be free from a single point failure with loss of primary instruments. The HDX meets the requirement for a primary system.
KT
 
Even if the probability of all the internal system component failures that can result in a databus failure is very small this is still a single point first failure that can result in loss of primary instruments.
KT

Don't forget that the Skyview bus is fully redundant, as already mentioned. You have in every DB9 on the bus, 2 pairs of bus wires. If one pair of bus wires is down, you still have the other pair of bus wires.
 
Remember that if you doing training IFR (RV-12iST) and your building ELSA then Garmin is the only choice. Building EAB, the world is your oyster.
 
Don't forget that the Skyview bus is fully redundant, as already mentioned. You have in every DB9 on the bus, 2 pairs of bus wires. If one pair of bus wires is down, you still have the other pair of bus wires.

I would like to believe that the skyview databus connector has two databusses that provide a complete level of redundancy if one fails but I cant find a description of the databus configuration anywhere in the documentation. I believe it may be hardwire configured with the HDX display units transmitting on bus 1 and receiving on bus 2 with all the other system units receiving on bus 1 and transmitting on bus 2 when they receive a valid address request. This is a much easier and cheaper protocol to implement and always has the HDX display in control of bus traffic. The HDX display that comes on line first grabs control (which may be why the recommendation to have the pilot side display on battery power and the second display through the master solenoid makes good sense). This bus timing protocol doesn't suck up a lot of bus bandwidth if implement in that way and could provide a larger bandwidth than two separate bidirectional busses where bus control handoff has to occur. But it doesn't provide any redundancy. Will continue to investigate to determine the bus protocol that is implemented.
KT
 
Now I remember why I'm a mechanical engineer instead of electrical.;). I am thankful that you guys exist, however.

I would like to believe that the skyview databus connector has two databusses that provide a complete level of redundancy if one fails but I cant find a description of the databus configuration anywhere in the documentation. I believe it may be hardwire configured with the HDX display units transmitting on bus 1 and receiving on bus 2 with all the other system units receiving on bus 1 and transmitting on bus 2 when they receive a valid address request. This is a much easier and cheaper protocol to implement and always has the HDX display in control of bus traffic. The HDX display that comes on line first grabs control (which may be why the recommendation to have the pilot side display on battery power and the second display through the master solenoid makes good sense). This bus timing protocol doesn't suck up a lot of bus bandwidth if implement in that way and could provide a larger bandwidth than two separate bidirectional busses where bus control handoff has to occur. But it doesn't provide any redundancy. Will continue to investigate to determine the bus protocol that is implemented.
KT
 
HDX redundant network bus

After a lot of searching I did find a couple of references to the hardware structure of the network bus. It is likely a RS485 based bus and is fully redundant according to page 12-12 of the HDX user guide that discusses warnings and messages. So my concerns were unfounded.

KT
 
Which truck is better Ford or Chevy? I say Ford
Which soda Coke or Pepsi? I say Coke
Which Primer or not to prime? I say prime
Which Avionic package Garmin or Dynon? I say Garmin


:rolleyes:

I was with you all the way...until the primer thing. I don't need no extra stinkin' primer...:rolleyes:

My preference is for Garmin. It's a common interface that I am familiar with and the integration with all of my components, notably the GTN navigator, is excellent and something I'm used to - a key point.

But that's my humble opinion.
 
Then I guess I gotta go home.:(. I went Dynon. Just ordered the servos.

Humans are terribly adaptive species. Maybe take a Dynon course to familiarize yourself with all the features it's capable of.... it's a very power packed device, with all the bugs on screen, designed to help you... it's quite a powerful unit for my simple mind. The last thing that I like in any device like this are really deep menu's. I hate 'em. Fortunately, once these are set up, the deepness of the menu becomes a non issue, and the Dynon feels pretty intuitive, at least, to me.

Can't speak for the Garmin, but I have used a LOT of their other GPS devices.
 
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Back when I had to make a decision (involving nutplates on the instrument panel. Obviously a decision that can be changed), I did some napkin math with the numbers of the Van's site and actually found it to be pretty much of a push between the two.

I don't think you can go wrong with either one, though the tribal nature of the world today will tell you you can.
 
out of the box

For anyone out or the LSA-area: ever thought of MGL? Much cheaper, simulator included, good service, take the opportunity to add some home-made wiring as well ;-))
 
Back when I had to make a decision (involving nutplates on the instrument panel. Obviously a decision that can be changed), I did some napkin math with the numbers of the Van's site and actually found it to be pretty much of a push between the two.

I don't think you can go wrong with either one, though the tribal nature of the world today will tell you you can.

I came to the same conclusion at that time too. At least for spec'ing "fully loaded" Dynon and Garmin solutions. The decision then became how much are the map/database updates going to cost me. The ol' printer vs ink problem.
 
Don't forget that the Skyview bus is fully redundant, as already mentioned. You have in every DB9 on the bus, 2 pairs of bus wires. If one pair of bus wires is down, you still have the other pair of bus wires.

And G3X has backup RS232 interconnects between the GDU, ADHARS LRU and engine monitor LRU as a failsafe backup in case of CAN Bus failure. Remember one of the attractions of CAN Bus in industry in the robustness of the interconnects when implemented and installed correctly. But the serial backup is nice.
 
I came to the same conclusion at that time too. At least for spec'ing "fully loaded" Dynon and Garmin solutions. The decision then became how much are the map/database updates going to cost me. The ol' printer vs ink problem.

I think we can thank Dynon (and MGL and GRT?) for the fact that a VFR North America data subscription for a Garmin G3X panel is only $200/yr. Add $300 more for IFR (GTN 650) for the U.S.
 
I can only share my experience, a few years back at Oshkosh I looked at the Dyon SkyView and the Garmin and I honestly don't remember the model, but the one for the RV12.
I had no experience with either but have flown many LSA's that have various similar systems. When trying out both system I found that for me the Dynon SkyView was much more intuitive. I could create flight plans by looking at the buttons or functions and figure it out. With the Garmin I could not, it was not clear to me, this could be that the user interface was just different or worked differently. It might be I am not "smart" enough for the Garmin ;)

Nothing scientific just my experience.
 
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