Can I get more than 2 mavlink connections out of a Pixhawk

Hi there,

Tried searching and came up with nothing

I have a 3dr radio on telemetry 1, and I have a OSD on telemetry 2.

I just brought a Taranis, and I would like to be able to pump telemetry down the FrSky protocol.

Is there any way to re purpose another UART as a third telemetry connection?

Side note: Is it possible to deliver 16 channels to Copter via SBUS? I see mixed reports.



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I can confirm similar with Graupner SUMD, and Hott Telemetry on Serial 4. Support for that specifically seems new and incomplete.

I have got 16 channels in to show up with SUMD. And there is this :


#define SUMD_MAX_CHANNELS    32

But then there is this :

#define PX4IO_RC_INPUT_CHANNELS        18
#define PX4IO_RC_MAPPED_CONTROL_CHANNELS        8 /**< This is the maximum number of channels mapped/used */

On the console shell, "px4io status" will tell you what is receiving.

So it receives 16 channels but they are not usable? I understand that plane allows this.

It would be awesome to be able to assign more channels to autopilot functions, and to have more channels available for the 7/8 options.

If you have an OTG enabled smartphone you can run Tower and not only will you get telemetry, you get full GCS functionality...

And you can use a modified Walkera Type B phone holder the mount the phone to your radio.


If you're using Copter-3.3.1 (latest official release) then it's possible to have 3 telemetry ports.  You can set the SERIALX_PROTOCOL (where X is 1,2,3 or 4) to "1" to enable it for MAVLink (other numbers can be used to enable it for FrSky output, GPS, etc).

Fantastic, thanks Randy, thats what I was hoping.

Yes, I do use Tower, which excellent, thanks for the tip on the phone holder, I have been looking for a way to mount the phone as well as my FPV screen. I am going to buy one of these for my screen:

Hopefully I can get some sort of phone mount going between screen and TX

It's hard to say... With latest Copter (master branch) and Mission Planner (beta download), under Full Parameter Tree there are RC1 thru RC14, but they don't seem to support all the Channel 7/8 options.

Not sure about earlier versions, cause I need the latest for SUMD. But I might get to testing some of that this weekend. I just recently upgraded from 6 channels, so just having 7/8 options is good enough for now. My TX is 12 channels, but it can set to 16 channel mode, and at a very low level Pixhawk shows 16 channels of values.

I'm sure the 32 channels in SUMD code is just protocol support, it's needed just to handle the checksums. But I see no reason for not having Channel 7-16 options.

I use a cheap mount from eBay  FPV Monitor Mount .

It raises the monitor so I have room for the phone...  


Yes, I have the same mount. Not super impressed with it to be honest, it does the job but I want to get the evolution one so that i can take the monitor on and off easily and be able to adjust the angle easily.

I just ordered a cheap phone mount which i can hopefully hack onto the tx somehow


I looked at different monitor mounts, but I couldn't find one that would coexist with the phone mount.

It does make the entire rig somewhat unwieldy, and having a strap around my neck was getting uncomfortable, so I got a Tarot tray.

The tray does the job, and the harness makes things much more comfortable, but I can't use their monitor mount because it interferes with the phone mount...

I guess in the end its all about compromises and using what works for you.

Fly safe, and have a great weekend.


Or you could also simply use a Y cable on telem 1 or telem 2 

No, that won't work for what he is trying to do.  The protocol for that port with the 'y-cable' would have to share the FrSky protocol, as Randy has described.

James, follow the wiki instructions:

I know that seems obvious, but . . .

As far as the 16 channels, yes, I have an X8R, X6R, and an X4R.  All 16 will show up in 'RCINxx' on MP using SBUS connection to the RCIN port.  Ch 9-16, 9-14, or 12-14 respectively can be output on the FrSky receiver's PWM pins in addition to the PixHawk seeing all 16.

Cool breezes!!


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