Failsafe on RX disconnect or depowered (PPM)

ArduPlane Plane 3.4
1

Hi,

I didn’t manage to get a clear idea from the manual about sbj. Please explain is there this case detection and what will be a following procedure?
Is it possible to test it somehow at the ground? I didn’t notice any state changes when I disconnect my receiver. All channels just freeze. No RTH enabled.
Thank you. (APM 2.5, PPM on in1)

2

look in https://github.com/ArduPilot/ardupilot/tree/master/Tools/ArduPPM/Libraries

3

Thanks, good info.
But nothing happens when I disconnect my receiver in PPM paththrough mode. All channels just freeze. According to that info a different behavior is expected:

If all contact with the receiver is lost, an internal failsafe is trigged after 250ms.

Default failsafe values are :

Throttle channel low (channel 3 = 900 us)

Mode Channel set to flight mode 4 (channel 5 = 1555 us)

All other channels set to midstick (1500 us)

5

For testing look at:
http://ardupilot.org/copter/docs/radio-failsafe.html
and
http://ardupilot.org/plane/docs/apms-failsafe-function.html

Make sure you test at normal and extreme input values on RC channels and observe change (some channels will might take last value, others go to a failsafe value)

According to :
https://github.com/ArduPilot/ardupilot/tree/master/Tools/ArduPPM/Libraries

In Passthrough mode:

// PPM PASS-THROUGH MODE (signal pin 2&3 shorted):
// -----------------------------------------------
// - Any input level changes on pin 1 will be passed directly to the PPM output (PPM pass-trough)
// + If no input level changes are detected or if the input signals stop, there will be no PPM output

There will be no PPM / PWM values output to the Ardupilot from the PPM chip.

Acording to :
https://github.com/ArduPilot/ardupilot/blob/ArduPlane-release-AVR/ArduPlane/radio.cpp

It should center the first 4 channels and leave the trottle at min (possibly 400 if no input)

Then if THR_FS_VALUE = 1
FS_SHORT_ACTN and FS_LONG_ACTN = 1

It should trigger circle and the RTL

Look at
void Plane::control_failsafe(uint16_t pwm)
in https://github.com/ArduPilot/ardupilot/blob/ArduPlane-release-AVR/ArduPlane/radio.cpp
https://github.com/ArduPilot/ardupilot/blob/152edf71891146abc588b86e5f4149405b794da1/ArduPlane/events.cpp