Walkera RX-SBUS 2.4G 12CH on Pixhawk 2.4.8

Hi all,

I Rebuild a Walkera Scout-X4 a while ago but got stuck with the original RX 709 receiver . The original has 8 PPM and 4 PWM channels . As i would like to use all the 12 channels of my Devo F12E trough the Pixhawk i got my self a Walkera RX-SBUS 2.4G 12ch receiver and connected it to the RC-In of the Pixhawk… All works like a charm , but i’m not 100% clear about how the fail-safes work … did any one do something like this before ?.. I know the fail-safe works with the "No RC Receiver " settings… but i cant find to much information about what happens when …
I did some testing , i noticed land , disarm and RTL actions on Radio disconnect…but like i said …whats the full story inside the Pixhawk and Ardupilot…


this link described fully about failsafe

Thank you for your answer , i read this multiple times . So if i’m right this is all there is ( i don’t think so ) ?. …What i’m missing and noticed (on bench testing ) is for instance when EKF failure is present there is no RTL but only a disarm and some times there is a warning "flight mode change failed " sometimes not … so that is the reason for my question … what happens when ?..I would like to know the whole procedure how the fail-safes are linked together .

As i know there is 4 type of failsafe
1- battery failsafe. will trigger when your batter go below voltage that you entered

2- radio failsafe. Will trigger when your throttle go below 975 pwm by default

3- gcs failsafe. Will trigger when you lost communication with your telemetry

4- ekf failsafe. The EKF failsafe will trigger when any two of the EKF “variances” for compass, position or velocity are higher than the FS_EKF_THRESH parameter value for 1 second.

To found out which type of failsafe is happening on your copter you should check log files

Thank you for your answer , it helps !. but there are some differences.
1-BF-Should work think its okay.
2- RF-Is not Throttle dependent in my case ,for as i can tell Throttle keeps last value.
is what i see , with the new Walkera receiver the only fail-safe message i see on Missionplanner ( or Qgroundcontrol ) is "No RC Receiver " ----failsafe---- (and then depending on flight status and other warnings ) land -disarm or RTL
3- GCSFS-Yes tested GrStation , and joystick loss… Gives "No RC Receiver " --> Failsafe.(and then depending on flight status and other warnings ) land -disarm or RTL
4- EKF failsafe Works , gives other actions when “No RC Receiver” fail-safe kicks in (for instance no RTL but “land” or disarm depending on flight status landed or not ect )…
5- When No EKF failure , then failsafe switches to RTL in stead of Land.
6- Depending on flight status sometimes Failsafe is not able to switch to the flightmode it wants “Message Flight mode change failed”

So see my confusion ?.. I think everything works just fine and better then the Hardcoded RTL in most Receivers ( like my former RX709) that only react to Low Trottle (poin-t2-) and set the FC in RTL ( CH5 Mode 6 ).
I think the Page http://ardupilot.org/copter/docs/radio-failsafe.html describes it well , but there is no complete description how its all linked together ?.

By the way , i’m still doing the test "no flying " .