Failsafe apm 2.5 with frsky and turnigy 9x


I'm not sure i'm doing good..

I 'm flying with an apm 2.5, rx frsky, tx turnigy 9x.

I saw the video of Mark Harrison on youtube ( ) explaining how to setup your failsafe setup on your frsky. I did it too..It workds ! nice !

In the manual of the apm 2.5,, the failsafe is explained of an other way :

Do i have to make the setup of the apm 2.5 like explained in the manual if i already follow the instruction of Mark Harrission (seup on the RX) ?




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    • You mean after switching your TX off or after switching your TX back on?? Back then with my FrSky gear it was the issue when you switch the TX back on and during startup it went through some init procedure which would output different values from what you taught for failsafe in the RX.

      Sorry, I am not much help reading logfiles...

      • Immediately after switching off my TX and my quad was in the air. Not during 'recovery' from TX off to TX on. Brt

        • Without looking at your logs I would say there is something wrong with your failsafe config on your RX. But you should be able to reproduce it on the bench while connected to the missionplanner.

          If you had multiple mode changes and if it was only between 2 modes maybe your RX outputs a PWM value that's right in-between two modes?

  • I was wondering if I may please get some help with setting failsafe as well.I am using a Turnigy 9XR with er9x firmware, apm 2.5 (arduplane), and Frsky DR8-II & DJT.

    I have been able to get failsafe working correctly by using the Frsky build in failsafe (as per Mark Harrison's video) however I am unable to get it to work by using the Tx method. The reason I am trying to get it to work via TX is if I am flying long range and have very brief losses of signal I want the failsafe to kick in but return to back to the exact settings I was in (ie. throttle position, flight mode etc.) prior to the signal loss, so I can continue flying.
    Basically what is happening is if I switch off the 9XR the apm 2.5 is throttle PWM range is staying at the position it was at prior to switching off the Tx, ie. if I am at 50% throttle (1515pwm) I switch of the 9XR and the APM stays at 50% throttle. If I then turn the 9XR back on, the pwm goes to 900 for approximately 2-3 seconds before going back to the 1515 it was at.
    If I am not mistaken should switching off the Tx should make the pwm go to 900 without having to turn the Tx back on? I believe because of this it is stopping failsafe from working correctly.

  • I too am having a hard time figuring this out.  First, off, I have a Frsky system.  I assumed I would not have to set any F/S setting on the receiver?  Perhaps I am wrong... I bound my radio/rx at -150%/+150%, then returned to normal travel (100%) and have it set up in MP correctly.  

    I.E.- My minimum throttle is 995 with throttle stick off.  My FS PWM value is 925, and when I shut my radio off, it goes to 900. This triggers the F/S and puts my plane into RTL.  However I get no throttle.  I assumed that I could set a F/S throttle setting in MP somewhere but I cannot?

    I tried to adjust my Ch 3 (throttle) min PWM value to say 40-50% but then it activates at any flight mode other than manual?  I am quite confused.  

    Another question, is how will an airspeed sensor effect this, as I have one, but I am new to APM yet, so to keep it simple I do not want to use it for the time being, but I would like to set a F/S setting to RTL, and a airspeed setting above stall, and have the APM run the throttle in F/S mode, is this possible as well?  Thanks in advance!!!! 

  • Developer
    You can follow Mark's instructions. The FrSky can set PWM values for all channels. A setting with neutral stick input I.e centered and with the mode set to LAND or RTL, is the same as you doing that on your TX.

    Some receiver's only support fail safe on throttle. This is when setting the PWM values in MP helps, as this is what the APM will use when that event occurs. I know Futaba has throttle Only FS.

    When you use FrSky failsafe to set the throttle below 975, to trigger the failsafe in APM the advantage is that the APM will not go back to the current stick positions when signal is restored. It will stay in LAND or RTL until you do a mode change.

    If using RTL as a failsafe,,you must make sure you have a good sat lock before taking off, otherwise the copter will not know the correct place to return too
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