it depends on the field of view of your sensors, at which angles do you get sensor coverage? And how is the data reported, e.g do you get one value per sensor at each timestep or do you actually get a range scan per sensor (and what would be the resolution of that).
But as an example:
I assume you have 6 sensors with fov 10deg, which all report one value per timestep. sensor 1 is located to the front of the drone and they are evenly spaced.
then you should fill the message as follows:
msg.frame = MAV_FRAME_BODY_FRD
msg.increment = 10 (degrees, resolution)
msg. angle_offset = -5 (degrees to shift, such the the fov of the first sensor is centered to the front of the drone)
msg.distances = [data1, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX
data2, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX,
data3, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX,
data4, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX,
data5, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX,
data6, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX, UINT16_MAX]
put UINT16_MAX where you do not have any sensor coverage. The drone will refuse to fly these directions
msg.