Info on Chan 9 to 16

Hi everyone.

This is my first build with a Pixhawk.

I have my Frsky receiver bound with telemetry and chans 9 to 16 available.

My question is can I get access to these higher chans in mission planner, if so how?

I have noticed if I set say RTL in extended parameters on chan 8. When I look in standard parms, the RTL is on chan 9. But in Full parms it is on ch8_opt. This is a tad confusing for me. Don't want to fly and try these until I am sure and understand what is going on.

Also is this where I can use the chan 9 to 12? If so do I set in Standard or Full parms as they appear to be out by 1 chan.

Is there any way I can use chan 6 for things other that what seems to be just tuning type things.

Thanks in advance Ken

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  • I just checked Mission Planner and changing CH10_OPT on the standard screen changed CH10_OPT on the full parameter screen.  No issue.  Please note that the description comes before the parameter option on the standard screen.  This was a little confusing to me at first.

  • MR60

    Standard paramsgives you a simplified subset of the parameters while full param lists all of them.

    Mode changes (like RTL) must happen through channel 5. You cannot use any other channel. So trying to set RTL mode through channel 11 can't be.

    Test your mode change in the corresponding screen in mission planner; you can define six modes. Each mode has its own PWM range. Read the Ardupilot wiki a bit.

    • Sorry Hugues,

      But totally disagree with your response, can set RTL on chan 7 and 8. Understand fully the modes on channel 5 and the PWM values

      I have set it on chan 11 in full params and it works.

      Ardupilot wiki is a tad old it gives no thought to a Frsky receiver with 16 chans.

      May I ask you to have a look in Config/tuning in Mission Planner, under extended tuning and the settings you can do for Chan 7 & 8.

      Then cast your eyes over config/tuning but this time full params and curser down to Chan 7_opt thru Chan 12_opt, have a look at these options for settings. They also work when set.

      Thanks for your response  Ken

    • MR60

      You are right, you can indeed use CH7 , CH8 for auxiliary functions, among which RTL.

      Here is what the wiki says:

      Auxiliary Function Switches

      This article shows how to set up which features are invoked from the transmitter’s auxiliary function switches (Up to/including AC3.2.1 you could only set the Channel 7 and 8 options, From AC3.3 you can set options for channels 7 - 12).


      AC3.3 introduces support for auxiliary functions on channels 9 ~ 12.


      By default the auxiliary switches are disabled but you can assign features using the Mission Planner‘s Config/Tuning | Extended Tuning screen or by setting the CH7_OPT (or CH8_OPT) parameter directly.

    • Thank you Hugues,

      Now I hark back to my original question.

      Why is there a difference between chan options in Standard and full params. You set something on chan 11_opt in full params and it appears on chan12_opt in standard params. Why? The functions works, I have tested it. But not comfortable flying around at distance and height because I am unsure of the outcome.

      I think I will put the Pixhawk on just a frame and motors and program these functions and go for it and see the outcome. If it crashes no great lose, motors, esc and controller usually survive.

    • MR60

      Have you tried another ground station software to verify if it is not a mission planner software bug?

    • I am running 3.3 in pixhawk and 1.3.38 in mission planner. I have loaded old version of mission planner  with the same outcome. Have tried it on Tower on my tablet, still no good.

      Like I said I think I will send and old bare bones frame up with a pixhawk on it and fly around and try all variations for a while and try and make sure it does not get tangles up inside pixhawk and crash.

  • Mission Planner does not display channels higher than 8.  You have to use the full parameter list to change these values.

    • Ok thanks for that Michael.

      So what is the difference between full params and standard params. So I set say RTL on chan 11 in full params why does it appear in standard param on chan 12. All the remaining chans are 0, do nothing. But when I set in standard param on chan 11 it appears in full params on chan 12.

      Why is this so and is it safe to fly like this?

  • I struggled with almost the same problem not a while ago. In my setup, X8R transceiver is connected to Pixhawk via SBUS. I expected all 16 channels to be available on the Pixhawk side, and wanted to hook my servo-style peripherals to the Pixhawk outputs AUX1-6 in pass-through mode... but it turned out that things are a little bit more complicated than that.

    First of all, you can configure your X8R in mode 3 or 4, so channels 1-8 are going through SBUS, while 9-16 are on the transceiver analog outputs 1-8. This won't work for L9R unfortunately as it doesn't have these modes.

    Secondly, if you connect your X8R or L9R to Pixhawk via SBUS, it does see all 16/12 input channels! I was confused by the Mission Planner monitor that plots only 8 first channels as a graphs on the ch_out_1..8 ignoring ch_out_9..15. Still, even not visible in the Mission Planner, you can route channels 9 to 15 to AUX1...AUX6. Well, most of them.

    Ch1_in -> RC1

    Ch2_in -> RC2

    Ch3_in -> RC3

    Ch4_in -> RC4

    Ch5_in -> x (used for mode switching). RC5 output is not working (or configured for FLAPS in Plane mode if RC5_FUNC=2 or 3)

    Ch6_in -> RC6

    Ch7_in -> RC7 (in Plane mode, this is an input for flaps routed to RC5...argh, so confusing!)

    Ch8_in -> RC8

    Ch9_in -> AUX1

    Ch10_in -> AUX2

    Ch11_in -> AUX3

    Ch12_in -> AUX4

    Ch13_in -> AUX5 (off by default. Increase BRD_PWM_COUNT by one to turn it on)

    Ch14_in -> AUX6 (off by default. Increase BRD_PWM_COUNT by two to turn it on)

    It doesn't answer your question if you can use ch9..15 in MP, but as long this is a related topic, I wanted to share my findings here too...

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