ARINC 429 Driving TruTrak Autopilot

[JohnAJohnson]

I have an Avidyne IFD540 talking successfully to the HDX through an ARINC 429 Module. By adding a second ARINC 429 Module, could one use the HDX to drive a TruTrak autopilot directly? In addition to just GPS lateral steering, I would think this could provide ILS and VOR steering to the TruTrak autopilot. Has this been tried?

 

[Rhino]

The HDX doesn't really drive autopilots. It has a built in autopilot that drives servos. Technically, an autopilot is usually driven by navigation devices, like a GPS. Why do you want two autopilots?

 

[jakej]

He has only 1 I believe, it’s a legacy TT unit. Maybe he wants to display the VOR/ILS on the Dynon HSI instead of a separate HSI/CDI?
Also something to do with the rate of Arinc data = slower for TT than most other Arinc equipment ?
We really need more info from the OP.

 

[JohnAJohnson]

Only one autopilot, a TruTrak. I would like the TT to fly off the HDX HSI, instead of the Avidyne IFD540. Reason is, no matter the source or type of signal (GPS or NAV), the TruTrak would follow the Dynon HSI.

 

[Rhino]

No, but you could get rid of the TT and just have the HDX drive the servos directly. You do have two autopilots, because one is built into the HDX. Your servos are very likely compatible with it.

 

[Marc_J._Zeitlin]

You do have two autopilots, because one is built into the HDX. Your servos are very likely compatible with it.

No they're not. Although GRT, MGL, Dynon and Trutrak servos look similar, none of them are interchangeable, and certainly none are interchangeable with Garmin servos.

But I'd definitely recommend selling the TT system to someone that wants a standalone A/P and get two Dynon servos. Then the A/P will follow whatever navigational device you're using - either the Dynon internal GPS, or the IFD540. Much simpler interface and usage, and by the time you sell the TT, the cost won't be prohibitive.

Now, if all you're doing is driving the TT from the IFD540, and you feed the IFD540 to the Dynon as a nav source as well, you can use the Dynon HSI while using the TT A/P. That gives you what you say you want without spending a dime or changing any hardware.

 

[Rhino]

My bad. I though Dynon used TT servos when they made theirs.

 

[JohnAJohnson]

But I'd definitely recommend selling the TT system to someone that wants a standalone A/P and get two Dynon servos. Then the A/P will follow whatever navigational device you're using - either the Dynon internal GPS, or the IFD540. Much simpler interface and usage, and by the time you sell the TT, the cost won't be prohibitive.

Can't. I'm stuck with the TT autopilot.

Now, if all you're doing is driving the TT from the IFD540, and you feed the IFD540 to the Dynon as a nav source as well, you can use the Dynon HSI while using the TT A/P. That gives you what you say you want without spending a dime or changing any hardware.

I am doing that now. But I'd like to have the TT fly off the HDX HSI instead of the IFD540. No matter the source into the HDX, I'd like the Dynon to steer the autopilot. I know - I could put a switch in to select the autopilot's source, but that is redundant and a kludge.

 

[Marc_J._Zeitlin]

Can't. I'm stuck with the TT autopilot.

You posted this in the Experimental and LSA section of the forum - how are you "stuck" with the TT?

I am doing that now. But I'd like to have the TT fly off the HDX HSI instead of the IFD540.

Why? What advantage does that confer? How does that change what the airplane does?

 

[JohnAJohnson]

You posted this in the Experimental and LSA section of the forum - how are you "stuck" with the TT?

Why? What advantage does that confer? How does that change what the airplane does?

These questions are irrelevant to my post.

A simple "No" to my question, "Has this been tried?" would suffice, and only trumped by no response at all.

I do try to answer a post when I have direct knowledge of or have successfully done what a poster has asked about. If anyone has information that would address my question, I'd appreciate hearing about it.

 

[Rhino]

You'll get a lot of trumps with an attitude like that. They were reasonable questions. Knowing the circumstances and limitations builders/pilots face helps to answer their questions. It can also help those in the future who may be faced with similar circumstances. But hey, it's your dime.

 

[JohnAJohnson]

You'll get a lot of trumps with an attitude like that. They were reasonable questions. Knowing the circumstances and limitations builders/pilots face helps to answer their questions. It can also help those in the future who may be faced with similar circumstances. But hey, it's your dime.

I appreciate that but, in this case, I'm not looking to rationalize my thought process, followed by the resultant, "you should do it this way" type comments. I can change course all on my own once I have the data I seek. So yes, in some cases, I would prefer a non-response. Not an attitude, just a request for help from anyone who has been down this road or understands the ARINC protocol coming out of the Dynon or expected at the TruTrak.

It's a big leap from my question of, "By adding a second ARINC 429 Module, could one use the HDX to drive a TruTrak autopilot directly?" to, "get rid of the TT and just have the HDX drive the servos directly". The response doesn't do anything for me; it only self-aggrandizes the poster, and while this is the internet and that's come to be expected, I don't care to play 20 questions toward that endeavor, with the obligatory belittlement along the way. Sorry to be so honest, but you seem to want to drill down on this.

As far as not getting responses - I will always answer a post if I can contribute. I hope others will do the same for me.

 

[Rhino]

There are no autopilot type commands sent over ARINC, so it doesn't appear it can do what you want. ARINC is intended primarily for position data to be input to the HDX, not output. There are output connections, but they appear to be limited to simple device communication and synchronization. So, I seriously doubt there's anything there you could use to drive an autopilot. But maybe someone more familiar with the data stream will chime in with something more helpful. Good luck, and let us know if you find a solution. It could be very helpful to future visitors here.

 

[JohnAJohnson]

There are no autopilot type commands sent over ARINC, so it doesn't appear it can do what you want. ARINC is intended primarily for position data to be input to the HDX, not output. There are output connections, but they appear to be limited to simple device communication and synchronization. So, I seriously doubt there's anything there you could use to drive an autopilot. But maybe someone more familiar with the data stream will chime in with something more helpful. Good luck, and let us know if you find a solution. It could be very helpful to future visitors here.

Thanks Rhino

 

[custom555]

I have an Avidyne IFD540 talking successfully to the HDX through an ARINC 429 Module. By adding a second ARINC 429 Module, could one use the HDX to drive a TruTrak autopilot directly? In addition to just GPS lateral steering, I would think this could provide ILS and VOR steering to the TruTrak autopilot. Has this been tried?

Did you ever figure this out? I have an HDX, TT AP looking at installing an IFD 540 and similarly I would like to run the AP from my HDX.

 

[John Tierney]

JohnAJohnson, what model TruTrak do your have? Some older models only took the RS-232 signal. I have been experimenting with a autopilot source switchs between my GNS480 and Bendix King xCruze110 (TT Gemini) and have gotten a bit of bad advice at times (from Dynon and TT) with people thinking the xCruze/Gemini is the same as the Vision. I previously had a TT ADI Pilot II in my RV-7A.

Regarding VOR/ILS, early on I only had an RS232 serial connection and one ARINC line FROM the GNS480 to the Skyview, plus and ARINC line TO the GNS480 from Skyiew. I learned that I needed to install a second ARINC line FROM the GNS480 to Skyview to get dedicated VOR/ILS signals.

My new setup (not finished/untested) uses a 3PDT on-on switch to allow ARINC and RS232 signals to come from either the Skyview or the GNS480 directly. It appears that Skyview may not be able to drive a TT on LPV approaches (no vertical signal from Skyview). I'm getting the RS232 out from one of the spare Skyview serial wired, configured for NMEA basic.

If my new setup works, I'll try to remember to post the arrangement back here.

 

[custom555]

JohnAJohnson, what model TruTrak do your have? Some older models only took the RS-232 signal. I have been experimenting with a autopilot source switchs between my GNS480 and Bendix King xCruze110 (TT Gemini) and have gotten a bit of bad advice at times (from Dynon and TT) with people thinking the xCruze/Gemini is the same as the Vision. I previously had a TT ADI Pilot II in my RV-7A.

Regarding VOR/ILS, early on I only had an RS232 serial connection and one ARINC line FROM the GNS480 to the Skyview, plus and ARINC line TO the GNS480 from Skyiew. I learned that I needed to install a second ARINC line FROM the GNS480 to Skyview to get dedicated VOR/ILS signals.

My new setup (not finished/untested) uses a 3PDT on-on switch to allow ARINC and RS232 signals to come from either the Skyview or the GNS480 directly. It appears that Skyview may not be able to drive a TT on LPV approaches (no vertical signal from Skyview). I'm getting the RS232 out from one of the spare Skyview serial wired, configured for NMEA basic.

If my new setup works, I'll try to remember to post the arrangement back here.

I'm at a crossroads, I have a TT Digiflight II a/p that would need the control head upgraded to an xCruze 100 to fly a coupled approach...or...I could switch to the Dynon servos and just use the HDX a/p. The second option sounds cleaner, but I've read a number of complaints about the Dynon a/p...not sure if they are all resolved yet. If I decide to upgrade to the xCruze 100, I'll be in a situation similar to yours. In that case could I use one 429 module coming off the IFD540 and have a switch that changes the navigation source to the xCruze between the HDX and IFD?

 

[John Tierney]

If you have one Skyview HDX and one Nav/Com/GPS you should only need one of the Skyview ARINC modules, as it has two ARINC-in channels and two ARINC-out pairs (same signal on 4 pins). Your Nav/Com/GPS probably has two ARINC-out channels available (GPSS and VOR/ILS on my GNS480), plus the RS232 signal.

I personally went with a separate TT/BK autopilot in case the Dynon system/screen/network crapped out, then I could use the wonky artificial horizon of the ADI Pilot II or xCruze 110 as a backup attitude indicator. That being said, the documentation and support on the xCruze has been pretty poor since TT sold out to BK. (BK doesn't even bring their experimental autopilots with them to the show at Airventure.)

If I had to do it all over again, I might use the Skyview A/P and find some other redundancy method, but that A/P didn't exist when I started my RV build in the early 2000's.