Passthrough not working with multiple radio receivers

I have a bit of a strange problem. I’m working on a drone which should use two RC protocols for demonstration purposes. The current plan is that there is always only one turned on. I’m using a Pixhawk 2.4.8, on the RCIN Pin I have a FrSky X6R and on Serial2 I have an ELRS Receiver. I also would like to have Yaapuu telemetry running on my radio, therefore I have a Passthrough converter on Serial1 with Protocol set to 10, on Serial2 I have the protocol set to 23 and the RC_Options bit for “use passthrough for CRSF telemetry”.

But I can’t get the Telemetry working on both, as soon as I enable the second I get the message “Passthrough telemetry conflict”. I understand that my case is an edge case, but shouldn’t this work when using RC_Options Bit 10 (Multiple Radio Control Receivers)?

Is there maybe a workaround by detecting which receiver is currently on and setting the according parameters via a lua script at startup?


I investigated a bit further, the message and also the reason why it’s not working can be found in in line 108 to 112.
Would it be possible to just change line 109 to

if (frsky_port != -1 && !multiple_RC_receivers) {


I also inverstiagted a bit into the idea with the lua script, I simply could set one channel to always high on one remote and low on the other and therefor detect which remote is currently connected and switching the serial parameters accordingly. But this would require a reboot…

Is there anything I’m missing?