I have experienced a weird behaviour when using the ports TELEM1 and TELEM2.
In my configuration I have an arduino mini connected at TELEM1 http://mediamax.pro/MAVLink2HoTT/
and a SiK radio connected at TELEM2 (see picture: https://ibb.co/hqUdTz )
Both have a baud rate of 57600 and both have the same SR1_ and SR2_ parameters.
Now: through the MAVLink2HoTT small program on the arduino I can see the telemetry on my MC-20 Graupner RC-Radio. As far as I start Mission Planner on my laptop and get a connection to the copter, I cannot receive the telemetry on the graupner correctly (wrong flight modi displayed, battery monitor changes continuosly, etc…)
It works very well as far I disconnect the mission planner.
It seems to me, that the ArduCopter HW doesn’t work with more than one UART interface working togheter.
Do you have the same problem?
Do you have any electric schematic of the last ArduCopter?