Failsafe on RX disconnect or depowered (PPM)


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)

look in

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)

For testing look at:

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 :

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 :

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

Then if THR_FS_VALUE = 1

It should trigger circle and the RTL

Look at
void Plane::control_failsafe(uint16_t pwm)