Radio Fail Safe not working with Spektrum Satellite

As I continue setting up my Octocopter I am setting up the radio. I am using a Spektrum DX7. I bound the AR8000 receiver with it’s satellite with a low throttle. I then disconnected the satellite and attached to the Pixhawk. Do the radio calibration, all is well. turn the radio off to check that throttle goes low and it does not move. Retry it a few times and same thing no throttle going to low when turning off the transmitter.

I reconnect the satellite to the receiver move it to my APM 2.5 connect Mission Planner and do a radio check, turn off transmitter and throttle goes low.

I tried with an AR6000 and get the same results.

On another note channel 5 and 6 seemed to be swapped. I followed the procedures here diydrones.com/profiles/blog/show … t%3A637661
and has worked fine on my APM, but on the Pixhawk channel 6 is controlling the mode

The PPM output is different when you only have the satellite attached to the Pixhawk than when it is connected to the main receiver and the APM.

Do the radio calibration, all is well. turn the radio off to check that throttle goes low and it does not move. Retry it a few times and same thing no throttle going to low when turning off the transmitter.

It won’t go low. That ability is only available with the main receiver connected.

The Throttle Failsafe will trigger after 2 seconds of no data coming from the satellite receiver.

I ended up using the PPM sum converter, all is well now. Thank you for the help.

If I understand this correctly, the throttle value will remain unchanged when the failsafe feature is activated if you’re using Spektrum sats. So as long as RTL is set for a failsafe condition, I should be able to reproduce this in APM Planner 2.0? In order to test this, does the Pixhawk have to be armed? Do I simply need to make sure the mode changes automatically to RTL when the Tx is turned off?

Hi Silverstoned83,

Here is how the failsafe works for Spektrum sats:
copter.ardupilot.com/wiki/thrott … e_receiver

You can test with USB connection, [color=#FF0040]without the battery connected[/color].

In Stabilize, Arm, throttle 0, then Tx off:
Will disarm

In Stabilize, Arm, throttle > 0, then Tx off:
Will change to Land, then will disarm

With mission planner will perform the same and will add the Failsafe message on the screen.

Also check:
copter.ardupilot.com/wiki/thrott … safe_works

I have just setup my f450 Quad with Pixhawk and a Satellite Receiver. I wanted to bench test my failsafe and have a question.

I throttle up my quad without props in Stabilize mode and then power off the transmitter. MP indicates that Failsafe activated and mode changed to LAND and within a second the motors stop with DISARM displayed. I tried to hold the QUAD in the air while doing this expecting the motors to stay on for awhile. How does the pixhawk know when the QUAD actually lands before disarming? Is it possible that if FAILSAFE is triggered say 20 m in the air that it could disarm before actually landing?

When it reaches the ground, the vehicle is not moving at the decent rate that is being commanded so the AP slows the motors, and continues until the motors are at their minimum values. after it has sat for several seconds with the motors at minimum and the vertical rate at zero it decides the vehicle is on the ground and disarms