Third HDX Display Wiring

[PYoder]

Dynon has a document detailing the wiring of a third HDX display (network hub for ethernet etc) - I have misplaced the one they provided to me some time ago - anyone have this document?

 

[Rhino]

I'm not sure what you mean by "network hub for ethernet etc." The SV-NET-HUB is serial. You can't combine it with ethernet. Adding a third display to the serial network would be as simple as plugging it into an SV-NET-HUB. Adding it to ethernet would be a different story, requiring an ethernet hub or switch. Making a physical ethernet connection between displays that way would be easy. But I'm not sure if anything else would be needed to make them talk to each other, because I don't know if the displays are configured to work that way. And, since two displays connect directly over an ethernet cable now, a crossover cable might be needed.If Dynon has a way to do that, I'm not aware of what it is. But if they do, maybe you should contact them and ask.

 

[PYoder]

I'm not sure what you mean by "network hub for ethernet etc." The SV-NET-HUB is serial. You can't combine it with ethernet. Adding a third display to the serial network would be as simple as plugging it into an SV-NET-HUB. Adding it to ethernet would be a different story, requiring an ethernet hub or switch. Making a physical ethernet connection between displays that way would be easy. But I'm not sure if anything else would be needed to make them talk to each other, because I don't know if the displays are configured to work that way. And, since two displays connect directly over an ethernet cable now, a crossover cable might be needed.If Dynon has a way to do that, I'm not aware of what it is. But if they do, maybe you should contact them and ask.

I understand the SV-NET-HUB connection - and that is not an issue. However the two existing displays are connected via Ethernet also - utilizing a crossover cable and that cannot be utilized to connect a third - an Ethernet hub is required - and while AC-powered hubs are common, 12volt hubs are not so common. In addition. A third display requires ‘splicing’ all of the data lines in with the two existing displays.
Dynon, at one time, sent to me a diagram outlining all of these issues - but they aren’t responding this week and I thought someone on this forum might respond more quickly.

 

[Rhino]

Then you'd just use an unmanaged hub or switch with standard cables, and ditch the crossover. I don't have the diagram for the rest. Sorry. I could come up with one, but I imagine Dynon will have replied by the time I finished it, and I have no desire to reinvent the wheel, so.....

If it's not something on their site though, it might be helpful if you post it here when you get it. That way, others could maybe benefit from it in the future.

 

[Marc_J._Zeitlin]

I understand the SV-NET-HUB connection - and that is not an issue. However the two existing displays are connected via Ethernet also - utilizing a crossover cable and that cannot be utilized to connect a third - an Ethernet hub is required - and while AC-powered hubs are common, 12volt hubs are not so common. In addition. A third display requires ‘splicing’ all of the data lines in with the two existing displays.
Dynon, at one time, sent to me a diagram outlining all of these issues - but they aren’t responding this week and I thought someone on this forum might respond more quickly.

So I don't know crap about having a 3rd display - I only have two. But you already know what you need to do for the SV-NET and for all the data lines (splice the third into the other two). For the Ethernet, see page 2-32 of rev. AT of the installation manual - it says:

Dynon Avionics strongly recommends “Low Smoke Zero Halogen” Ethernet cables for use in aircraft,but any Ethernet cable – whether it is a “crossover” or normal “straight” type Ethernet cable - will technically work. Low Smoke Zero Halogen Ethernet cables are available from Dynon Avionics (SV-ETHERNET-3CC). Aircraft containing more than two SkyView displays will need an Ethernet switch with enough ports to connect all SkyView displays together.​

So it seems as though ANY cable - straight or crossover - will work, and all you need is a 12V switch, like this one:

https://www.amazon.com/Industrial-3-Port-Gigabit-Ethernet-Switch/dp/B0DHFWCG2B

I'm sure there are a zillion others. Doesn't look very complicated... The hardest part will just be splicing in all bazillion data wires to the existing harness.

 

[Rhino]

A crossover cable has pins reversed from a standard ethernet cable, so they are not interchangeable. Dynon uses a crossover cable because the displays are normally hooked directly together, and crossovers are commonly used for directly connected equipment. For instance, you use a crossover cable when you connect two computers together directly, without a hub or switch. But when going through an ethernet hub or switch, you cannot use a crossover cable. The hub or switch assumes all connections are standard cables, and internally routes the data accordingly. The Dynon recommendation is because, no matter which configuration cable you use, a Low Smoke Zero Halogen is preferred due to better safety in the case of a fire.

 

[Marc_J._Zeitlin]

My point was, with a $40 switch and a couple of ethernet cables, the OP can have what he wants. Seems simple enough.

 

[Rhino]

I agree. It's patching in all the other stuff he wants that will be his biggest challenge. I knew what you were getting at. But you appeared to say any cable, including a crossover, would work with a switch, and it won't. I just didn't want anyone to mistakenly assume it would.

 

[PYoder]

My original question was in search of the Dynon ‘document’ that spells out the ‘process’. I appreciate the responses that basically outlined what I remembered. Dynon has not responded so I thought I’d try to shortcut my inquiry!

 

[palmqug]

@PYoder I'm about to add a 3rd skyview classic myself and came across this thread when searching for the same answers you requested. Did you get resolution from Dynon that you could share?

 

[PYoder]

Dynon has not responded and I have not yet added the third display. I’m rather torn between keeping my ipad mini in that spot with ForeFlight and switching to the 3rd HDX. Let me know if they respond to you.

 

[chriscalandro]

I don’t know that there is a “process”. It’s all in the install guide.

As to there not being many 12v network switches, that’s not true. Nearly all small gigabit switches are 12v

 

[PYoder]

I don’t know that there is a “process”. It’s all in the install guide.

As to there not being many 12v network switches, that’s not true. Nearly all small gigabit switches are 12v

Perhaps it’s been added to the current install guide, but ‘third display’ details were not in the install guide a couple years ago when I did my install - Dynon provided supplemental guidance upon request.

 

[Rhino]

I've never seen it either. But I think he's referring to the physical install for displays in general. It's all network connections, except for a few extra wires, and most of those, if not all, would connect in the same way as the other two. There might be a slight difference in audio connection, but I doubt it. Aside from that, the only real difficulties might be in the setup on the display itself. I've never really thought about how that might work. For instance, how would a third display acknowledge and comply with a master screen selection on the primary? Would software updates come from the master? That kind of stuff. I imagine it would be the same, but I don't know for sure.

 

[chriscalandro]

The only thing the Ethernet port gives you is sync between databases as far as I’m aware. I do t think it’s worth the extra effort to add a switch for that, rather just update the displays independently.

Everything else is through the Dsub.

 

[Rhino]

Or Wifi.

 

[palmqug]

I find it sad that Dynon advertises 3 screen capability, but then doesn't publish installation requirements or instructions. In my naive mind, I thought adding a third display to just repeat data already wired into the other two displays (replacing an EMD-120 with EMS-220 and 7" Skyview) would not require anything other then the two network cables (Cat5 and DB9). That is clearly not the case.

So my question now is what, other than power and ground, does 3rd display need from 37pin connector? Debating if I need to buy another full harness (or just DB37 connector for a few wires) and if I wanna hand this off to my avionics guy or do it myself.

Thanks for all the help. Dynon support has not been very responsive lately.

 

[Rhino]

This isn't support. This is a customer forum. You can't complain about support if you haven't actually contacted support. You also can't expect any EFIS to operate without the required data inputs, hence the 37 pin DSUB. You're laboring under unrealistic expectations. You can buy the harness, or build it yourself.

 

[palmqug]

Rhino, first I really appreciate all the info you provide on this forum and your quick response. However, I feel your making some assumptions that aren't valid in your reply. I understand this is a forumn and I have contacted support via email. They have not been very responsive lately on two separate topics. PYoder says he has also asked for info on this topic a couple months ago and has not received the info. I plan to reach out to them again, but both of us found ourselves here due to lack of published documentation or timely reposnse from Dynon support.

As for required inputs, its a networked system and all the inputs are connected to the system. If designed to do so, a 3rd screen could get all the data over the network instead of directly. I know now it at least needs power from the DB37 but exactly what else is the question.

Finally, I don't think expecting a company to publish documentation on how to install their product in a manner they advertise as supported is an unrealistic expectation. You even noted some of the outstanding questions in one of your posts above. I know I can buy a harness or build my own, but deciding which makes the most sense totally depends how how many of those 37 pins are really needed for a 3rd display when everything is already wired into the other two screen's.

Thanks again for all the help.

 

[Rhino]

Glad to hear you contacted support. Your comment wasn't clear on that, so it appeared you were referencing the forum instead.

I agree on the documentation. Several things are wired into each display, GPS, transponder and ADS-B for instance. They don't share those things, so all have to be wired.