Problem with Flight Mode Evaluation Diagram

#1

https://dev.px4.io/en/concept/flight_modes.html#flight-mode-evaluation-diagram

Hi everyone, I’m configuring my RC according to the diagram above, but it comes with some problems.

  1. If RC_MAP_MODE_SW was set to 0, means no channel controlling it, how would it work when comparing MODE_SW with other thresholds?

  2. I’ve set RC_MAP_FLTMODE to channel 5, and according to the comment:
    Comment: If this parameter is non-zero, flight modes are only selected by this channel and are assigned to six slots.
    what is the “six slots” ?

  3. When I arm my drone with MAVROS when it’s in STABLIZED mode, it sometimes auto change to POSCTL or ALTCTL so that it can’t continue to turning to OFFBOARD mode.
    For example, here’s my ideal procedure:

  4. when power on : STABLIZED DISARMED;

  5. arm with MAVROS: STABLIZED ARMED;

  6. then enable offboard : OFFBOARD ARMED.
    But sometimes, it goes like this :
    1.power on : STABLIZED DISARMED;
    2.arm with MAVROS: (POSCTL or ALTCTL) ARMED;
    3.then enable offboard failed.

The px4 ver is 1.8.2, any hint tosolve? Thx