CTLS equipped with a Garmin GTX330

[Roger Lee]

Posted for another forum member,

 

 

I recently bought a 2008 CTLS equipped with a Garmin GTX330, Garmin 496, Dynon HS34, Dynon D100 EFIS and Trutrak autopilot. The RS-232 output from the GTX 330 and the output from the Dynon HS34 are both connected to the data-in wire for the Garmin 496. With this configuration I get aural traffic warnings (TIS) from the GTX 330 but the traffic display does not show up on the 496. The connection between the 496 and the Dynon equipment seems to work OK. I get wind data on the EFIS and the autopilot operates in the heading hold and GPS mode. I had an avionics tech look at the wiring and he said the wire from the Dynon HS34 was not required so he cut it. I now get TIS data on the 496 but the connection to the Dynon is required as I have lost some functions. No wind data is displayed on the D100 EFIS and the autopilot will not operate in either the heading hold or GPS mode.

The way the wiring was installed is consistent with the wiring diagram that accompanied the airplane. It appears that the two digital input streams from the GTX 330 and the Dynon HS34 cannot be just spliced into the 496 data-in wire. Is there some way to get the two sets of data to the 496 with only one data-in wire?

 

 

Dick Johnson

Tucson, AZ

[Anticept]

The HS34 requires both in and out connections. These serial connections are analog, and require a looping path to function. The HS34 has a Serial 1 and Serial 2. It will have a looped connection with the GTX330, and a separate looped connection with the 496. The HS34 then communicates the information to the EFIS, and forwards all TIS, Altitude, etc information to the appropriate places. Appendix C, page 7-13, Dynon HS34 Serial Connections, and Appendix C, Page 7-16 of this guide illustrates it requires both xmit and receive to be wired: http://www.dynonavio...Guide_Rev_H.pdf .

 

CTLSs also come equipped with Serial 1 connection run through the center console with a male and female D-Sub connector. This is so you can easily hook up a computer and update firmware. Unless you want it to be a pain in the ass in the future, try not to bypass the d-sub connectors.

 

I myself am also having a problem though. I have a Zaon unit that I want to permanently install, but since the analog pins are already in use, I have no way of doing so.

 

EDIT:

 

Also, the data out wire from the GPS is split so it runs to the HS34, and a separate wire to the TruTrak autopilot.

[dick747]

The data in wire for the 496 is yellow , the data out wire for the GTX330 is violet and the data out wire from the HS34 is grey. This matches the wiring diagram for the CTLS. Don't think you can dump two independent data streams into a single data-in wire to the 496. I owned a Remos GX with the same equipment and everything worked OK. Don't know how it was wired.

[Anticept]

Roger,

 

Did my post help?

[Roger Lee]

Hi Anticept,

 

I posted it for dick747 because at the time he was having trouble with posting, but he looks like he's up and running now.

[dick747]

'Anticept, thanks for your input. I am aware of the diagram of the Dynon HS34 serial connections on page 7-13 of the D100 Installation Guide. Page 7-16 shows a more specific diagram of the connection with a Garmin X96(I have a 496). I have no idea what the output from the HS34 is that would be sent to the 496 but it appears to be important as when this connection was removed I lost several functions on my D100 and autopilot. I have a call into Dynon hoping to get more info. The other possibility is that when the Avionics guy was working on the problem he might have disconnected something else - perhaps the data-out wire from the 496. I am going to pull my panel tomorrow and make sure that everything is connected.

[Anticept]

dick747,

 

BOTH input and output on each lane must be connected to each serial device. That means the GPS will have line coming from the HS34, and a line going back. The GTX330 will also have, on the other serial pair, a line going to it, and a line going back.

 

Serial connections require a loop. This is comparable to ethernet. We call them twisted pairs because being a pair is literally their purpose. In order for the signal to work, there needs to be an electrical loop. There are 8 wires in ethernet, in 4 pairs. ANY signal sent out on one line will come back on the other line of the twisted pair. Same with serial connections. We return electrical flow through these loops, instead of via a ground, because there is MUCH less noise, and serial connections are EXTREMELY sensitive to extraneous noise.

 

What the avionics guy did was cut the loop. Your plane is miswired, and for some reason, it had the loops intertwined. Each device must have a separate loop or it will not work.