Testing Failsafe using X8R receiver.

Using the test methods outlined in the arducopter wiki, it seems that the method described does not give the intended results if the receiver uses sbus/cppm such as the FrSky X8R.

Is there an updated test method to verify failsafe for this type of receiver?

Here is my experience:

I have a FrSky X8R which I think I have configured for Option 2 Failsafe (no pulse/signal). There doesn't seem to be any obvious way to verify that no signal is set rather than option 1.

I followed the instructions on the Arducopter wiki ([url]http://copter.ardupilot.com/wiki/throttle-failsafe/#set-up_for_no-signal_method[/url]) but did not see the same test results.

All tests powered via USB and with MP connected to Pixhawk. Radio failsafe settings in MP are "Enabled always RTL", FS Pwm = 960 (my low THR value is 982).
Radio is 9XR Pro running latest firmware (ersky 9x 218).

Test 1:
When I turn the transmitter off to simulate a communication failure, *ALL* the Radio IN bars go to zero/white. In the demo videos only the throttle bar (3) drops to zero.
EDIT: It seems that this may be because I, and others seeing this, are using Sbus/CPPM on the 8XR receiver.

Test2:
It is not possible to run test 2 since if the throttle stays at zero, the Pixhawk will disarm itself!

Test 3:
Seems to work OK apart from showing no radio IN bars after switching off the TX. On completion, I did notice that the safety switch on the Pixhawk stays on solid red even though the MP display shows Disarmed/Failsafe.

Test4:
The Pix disarms at the end of test 3 so impossible to continue this test. Cannot arm again after the failsafe without powering off.

So 1 out of 4 is not exactly reassuring . . . . 

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Replies

  • MR60

    Hi Robin,

    The failsafe with "no pulse" method, using a taranis and X8R works perfectly well, even if using SBUS. I know that the wrong information is given around some forums, often by the same guy, that this does not work with SBUS. It works.

    Your issue (the fact you do not see the channel bars, in mission planner, go blank when turning off your Taranis), is mostly probably due to the transmitter/channel mode you have set on the Taranis when you have done the binding procedure with your X8R (I did the same mistake).

    Assuming you will use a D16 mode,

    1-in the first page of the taranis where you have the "bind" button, you have below that an option to set : hold or no pulses. You have to set it to "no pulses".

    2-Then you redo your binding with the X8R.

    3-You configure your X8R's failsafe as "no pulse". You do it without anything connected to your X8R, except a 5V/GND lead to power it on.

    4-You reconnect your X8R to your pixhawk and go in mission planner to the failsafe screen.

    5-You turn off your Taranis =>you should see all channel bars go blank on this mission planner screen.

    Cheers,

    Hugues

    • Hi Hugues,

      Thanks for your thoughts, but since I am not using the Taranis radio, I am unsure of your reply.

      My radio is the Turnigy 9XR Pro running ersky9 firmware (r218). I have looked on the radio, but do not see a comparable failsafe parameter to set to "no pulse" even though I think I have set the receiver to this mode.The receiver is set to D16. 

      When I switch off the transmitter to simulate the communication failure, I *do* see every channel bar go blank (step 5 above). This is what I am concerned about since the arducopter wiki and all the videos I have seen on the subject show only the throttle channel drop to zero. 

      Are you saying this is correct behaviour?

      • I have the X8R, all channels go to 874 or "blank". When simulate on the failsafe screen , it does go to rtl.

        Have not tested it with motors though.

      • MR60

        Yes , the fact you see all bars go blank is what you want for setting the failsafe based on radio link loss. The only alternative is to base the failsafe on the CHannel3 (THR) going under a certain PWM level value but this is not advised to use.

        • Thanks for confirming. I can get a good nights sleep now :)

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