I'm using APM 1.1.59 and APM board v1 (red board, ATMEGA2560). Uploading a new Firmware through Mission Planner works fine, also CLI has no problems to connect to the board. But when I try to use the SETUP mode of Mission Planner (not the CLI setup) I'm not able to connect anymore. (right top corner: Arducopter2, COM3, 115k) selected. I get a timeout (no heartbeat). The RX LED indicates that it receives data, the TX is board flashes intermittend on/off.
Any suggestion, hints (or a simple point-to-discussion XYZ) would be highly appreciated!