Absolute Noob, Pixhawk + D8R-II plus + 9XR + Hextronik telemetry

Hello everyone,

 So today i've received all my parts to build an FPV plane and have been assembling as well as calibrating all the equipment and have reached two bumps in the road.

Firstly I cant connect my Pixhawk to my laptop via telemetry because the air station is blinking to indicate its looking for radio's when my ground station is on and on APM planner 2. APM planner two is showing RTL in the top left and a slowly fading and lighting red light, no idea what that means :(. The Red and green lights are both flashing on the air station telem, and the ground is only flashing green.

Secondly, I've got a D8R-II plus receiver and transmitter module plugged into a 9xr and have NO clue how to connect the receiver to the pixhawk. Scouting around there's been a few mentions about having to change the receiver to PPM for it to be able to talk to the pixhawk. Im Pretty stumped at this moment, having only built a 4 channel plane before hahaha.

Anyways ANY help is greatly appreciated.

Thanks a bunch

Rhys Gittoes

(I've put some photos of the set up attached)

PS one of the photo's shows the air telemetry attached to the pixhawk, as you can see the wire provided is only 5 pin (only using 4 however) where by the pixhawk is 6 pin. Is it ok to attach it like that?

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You can't connect a D8R receiver directly to Pixhawk because it does not have a CPPM ouput, only eight separate PWM outputs. Pixhawk needs to be connected via a single servo wire between its RC In port to the receiver (CPPM port or  "Sbus" in the case of FrSky receivers).

Or, alternatively you have to get a PWM to CPPM converter which will adapt your PWM receiver to the single CPPM port of Pixhawk.

For the radios (telemetry), did you configure each of them to have the same "net ID"  and same communications parameters ? You can do that, one radio at a time, via mission planner, intiial setup, optional hardware, 3DR radio menu. You then click on a button named "load settings" to see what the parameters are. One of them is "Net ID". You change it to a value you choose and click then on "save settings". You do the same operation with the second radio module.

I have a D8R and use the SBus out on the D8R to the Pixhawk in.  Works great.  Also have a 9XR Pro transmitter that works with all 16 channels.

Can't help you with the radio's.  I use 3DR radios and it requires the 6 pin cable to the radio.  The 5 pin cable is for an APM board.  Not compatible. Plus voltage and ground are on opposite sides of the connector.  Check the website for the correct pin outs.

Hello thanks for the quick reply.

Ok so it seems i'm going to need some more hardware then correct?. I'll look online for one of those :)

For the telemetry I cant see that Net ID of each one, under status it just says fail?


Michael, Where can i locate the Sbus on the D8r and to which port did you plug it into? 


Rhys Gittoes


 Found an encoder in the packaging for the FR sky receiver so that i can connect it to the pix hawk :)

Also i've connected my ground station to the computer, and checked the net id which is 25, however i CAN'T see my Net Id of the remote telemetry. How would i go about doing this?!?! 


Rhys Gittoes

I think Michael is mistaken, the D8R II plus does not have any other outputs than the 8 PWM.

I see you have a air unit without a USB port on it. So to connect it to the computer you need a FTDI to USB converter cable or unit (3.3V) like this one : https://www.sparkfun.com/products/retired/8772

Ok guys, Thanks for all you wonderful advice. Telemetry Is all up and running, only problem i'm unfortunately having is that i'm not getting any responce from my RC receiver when plugged into the Pixhawk through the Encoder. I've tested it with a simple set up to ensure its not fried or anything and it works absolutely fine. However when i connect it to the pixhawk through the encoder, nothing happens (no lights etc on the receiver). 

This is probably due to a mistake in my wiring, any ideas? could the encoder be fried!?!

Thanks a bunch guys

Rhys Gittoes

BTW no clue where that brown wire goes? any ideas?


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