HS34 INOP ... Autopilot Confusion

[TheFrisco]

Looking at buying a 2008 CTLS, liking lots about it but have an autopilot questions. So THANKS in advance for your help, been a great forum and resource of information.

Looks like altitude hold is working but the HS34 is missing. What does that mean? What can and can't I do with this setup?

Current owner told me that Dynon took a look at the HS34 unit and its working but something else is INOP on plane so its not installed. Anyone else seen this?

Thanks Robert aka TheFrisco

[Tom Baker]

I can't tell from the picture what comm radio it has, but unless it has a SL30 there is no need for the HS34. It has a Tru Trak autopilot, and everything is controlled from the head on the left. The HS34 is designed for operation of the Dynon autopilot, and controlling the HSI on the D100 if you have VOR capability. 

[TheFrisco]

1 hour ago, Tom Baker said:

I can't tell from the picture what comm radio it has, but unless it has a SL30 there is no need for the HS34. It has a Tru Trak autopilot, and everything is controlled from the head on the left. The HS34 is designed for operation of the Dynon autopilot, and controlling the HSI on the D100 if you have VOR capability. 

Yes I believe it is an SL30. So that means I won't see anything on the D100 but with the HS34 I would get full VOR capability on it?

[Tom Baker]

I personally have not flown with a HS34. It is my understanding that it allows the HSI in the D100 to be controlled more like a traditional VOR from the knobs on the HS34. If you do have a SL30 I think you can still do everything you need from the buttons on the D100, but just not as easily. 

[Anticept]

The HS34 provides additional serial interfaces, aural notifications, and a more direct interface to various d100 settings instead of using the submenus, and HSI functionality.

It's basically an expansion bay.

The AP74 is the autopilot interface.

[TheFrisco]

9 hours ago, Anticept said:

The HS34 provides additional serial interfaces, aural notifications, and a more direct interface to various d100 settings instead of using the submenus, and HSI functionality.

It's basically an expansion bay.

The AP74 is the autopilot interface.

Any idea why it wouldn't work when Dynon says unit itself is good? Any common failures?

[coppercity]

In my experience with serial its usually an incorrect baud rate setting on a device or a broken TX or RX line. 

[Anticept]

There's settings in the EFIS to get the HS34 working. And as coppercity said, baud rate is important. It's pretty technical configuring the system, you need the manual for every single device and need to look at the tech specs. Usually baud rates need to be 9600 or 4800.

Finally, due to the way the HS34 needs to be wired in, you can't just 'remove' the hs34 and have things work. If you remove an HS34 from a dynon install with a d100 and d120, they would be unable to communicate with each other or GPS at all. Similarly, installing an HS34 would require rewiring the serial lines.

That Trutrak autopilot is completely self contained. They have their own static line, orientation sensors, and such. The only thing the autopilot requires externally is the GPS information for the track so that it can hold a course.

[TheFrisco]

UPDATE AFTER SOME RESEARCH

So it turns out the HS34 was removed because it caused problems with the SL30 NavCom, or to be more specific it started to switch frequencies on its own and showed "Com Failure" errors.

This lead to the realization that there must be a problem with the serial connection between the SL30 and the HS34.

I am in the process of switching the serial wire now, just waiting for parts.

And yes, taking out the HS34 was a non workable idea by the previous owner because it means that for example none of the EFIS/EMS alarms come thru the headset ... No stall warnings, no engine warnings, nothing ... Ouch!!!

Thanks to everyone's help here, such a great community,

Robert