RSSI failsafe doesn't trigger

ArduCopter Copter 3.5
1

I’m flying a pixhawk 2 with ArduCopter 3.5.7 with Taranis X9D Plus and TBS Crossfire. The Receiver is connected over PPM at RCIN + Mavlink at Telem2.
I injecting the LQ signal to channel 12 for RSSI.

The config looks like this:
RSSI_ANA_PIN 0
RSSI_CHAN_HIGH 2000
RSSI_CHAN_LOW 1050
RSSI_PIN_HIGH 5
RSSI_PIN_LOW 0
RSSI_TYPE 2

My problem is now, if I shut the Radio off I can see RXRSSI dropping to 1000-1001 and the Copter starts to descent with 4,5 m/s until it hits the ground.

The RSSI failsafe just never triggers.
Do I overlook anything?

2

AFAIK there is no such thing as RSSI failsafe in arducopter. Set your radio to output low throttle when connection is dropped and set throttle failsafe accordingly.

3

Ok that helped me so far. I’ve now configured the cut off in the receiver.

Apart from that I find this page (http://ardupilot.org/copter/docs/common-rssi-received-signal-strength-indication.html) a bit misleading.

Why can you set the limits for RSSI if they are not used?

4

Limits are for scaling the different RSSI system inputs to a common 0-100% range.
RSSI commonly used as a indicator for degrading radio link, but no system uses it for direct failsafe, since it can be misleading and values changes, especially at the end of the radio range, can be erratic.