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D100/HS 34 and GNC 355XL compatibility question

trib

Well Known Member
I'm looking to upgrade the GPS comm on my 6A. I currently have a 300XL connected to an HS 34 feeding my D100 HSI. Works great but would like to upgrade to a new Garmin 355XL GPS/Comm and get the improved display and WAAS with LPV capability. I contacted Dynon to ensure the 355 was compatible but was told it was not fully, that I would get horizontal guidance and display only, not vertical (including AP working horizontally only). The answer was a short "no, will work only horizontally" with no explanation. I did some manual lookup that does not appear to agree and sent it to the tech rep, but still got only the short answer with no explanation, although it seems that the manual information directly conflicts with the response. Has anyone connected a Garmin WAAS GPS to their D100/HS 34 and had it work correctly with vertical guidance? This is a bit frustrating to me as it certainly seems that it is stated to work. The literature implies this is a main benefit of the HS 34. Below is the information from Dynon which is applicable that to me conflicts with the tech response. I appreciate any feedback.

TR

Expanded HSI Navigation Interface: While all of Dynon's EFIS instruments currently include HSI functionality, full compatibility with some GPS and NAV radios has been limited by the serial connection method.

The HS34 overcomes these restraints by adding ARINC-429 and serial interfaces to cover many popular radios. With the addition of an HS34 to an EFIS, full compatibility is now possible with radios such as the Garmin 430/530. This includes advanced features IFR pilots demand, such as CDI auto-scaling and full vertical guidance information from WAAS-enabled units. The HS34 effectively eliminates the need to install a conventional CDI/GS head.

Some additional details from the D100 installation manual, Appendix for the HS 34, pages 7-13. Page 7-15 also shows a wiring diagram specifically for connecting to the GNC 300 series GPS.

" The three diagrams on this page depict generic device connections for devices outputting ARINC, serial, or analog data. If your device outputs multiple types of data, connect only one type to the HS34 in the following preference: ARINC preferred over serial; serial preferred over analog. ARINC data streams contain more information (vertical GPS guidance, GPS steering, etc) than serial streams and allow more control of your external device. Likewise, serial streams contain more information than that carried over analog lines. If your device is one of those listed in the next section, Common Device Connections, you may ignore this section. See page 3-4 for a chart of supported GPSs. "
 
This wouldn't be the first time that a phone representative at a company didn't fully understand their own products.

Suggest you keep calling until a knowledgeable person answers or maybe try email. Pretty sure that all EFIS makers support vertical CDI display and AP control from any ARINC based source. Dynon requires the HS34 for ARINC. Confusion probably came from the fact that vertical data is NOT transmitted over the serial port on most navigators.

Larry
 
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D100 and HS34

Tim,

First, The Garmin unit is a GNC355, not a GNC355XL.

I did an install of a GNX375, same unit with a transponder and not a comm, in a RV6 years ago which had a D100, and AP74. He did not have a HS34 and was he not going to buy one, as he was going to upgrade to SkyView, which he still has not done.

Now, it worked fine in lateral guidance as we just used the serial output, but with a HS34 you will have an ARINC429 input, so if you connect the GNC355 ARINC429 output to the HS34 ARINC429 input, you will have vertical guidance displayed on your D100 HSI.

By the response Dynon sent you, I think he did not understand the question or didn’t know that you have the HS34 module.

Brian
 
I did this homework when I was upgrading the LSA I had a couple years back. Please go to the Dynon forum and search Garmin 355 and you will come up with a few threads. Although I never completed the instal before I sold the plane all signs pointed to this being doable via the ARINC inputs on the HS34.

Good luck, wish I could be of more help
 
Dynon response

Thanks for the feedback. I talked with Dynon again and the response is that they acknowledge that their manual and literature say the D100 with the HS 34 will show vertical guidance on the HSI but all of the technical personnel that had experience with the D100 are no longer there and they have no first hand knowledge to verify it will work. The reply is also that the AP will not follow vertical guidance either way. I'm going to start a new thread and see if anyone has installed a WAAS GPS and see if I can find someone who has actual experience.
 
Tim
I have the GNX375 connected to a HS34 and a D100 and the HSI shows vertical guidance fine as well as on the EFIS display. I can send you the connection information.
I do not know about the Dynon autopilot but my installation is connected to a TruTrak Gemini autopilot and the system flies fully coupled approaches with vertical guidance.
The GNX375 is connected to the D100/HS34 via arinc 429 which provides the vertical guidance component.

If I remember correctly the Dynon manuals show connections to 430's etc so I do not know why a newer garmin navigator would not work but the forums had good information as suggested so check them.
Figs
 
Dave,

Thanks for the information. That’s just what I was looking for. Someone who had actually successfully installed the combo and had vertical guidance showing on the HSI. Dynon tech response to me just had me unsure so I was looking for real world experience
 
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