problem in changing mode when the copter is armed in The Pilot Lounge Posted April 30 · Report reply 56 minutes ago, erfan said: 1) Firmware-v2.px4 2) Mission planer 1.3.66 3) pixhawk 4) Tranis x9d plus . reciever is x8r frsky 5) I tried to connect once with Telemetry Radio baud rate 57600 and also usb 115200 You have pretty much the same components as I've used in my builds. 1) Is this the version that is displayed in the top left corner of Mission Planner ?. I would have expected something like Arducopter 3.6.8. Are you using Ardupilot or PX4 firmware ? 2) I am also running that latest version of Mission Planner 3) Is that a 3DR Pixhawk or a clone like the one that I have that's maked "Pixhawk 2.4.8" 4) I have the x9d (not the plus) running OpenTX 2.2.x along with the X8R receiver. 5) Those are the recommended speeds and I've used the same.