How does this IMU work and how to convert its output into meaningful information?
Regarding the Specified IMU

The referenced document describes the output protocol.


  SAEJ1939 CAN 29 bit identifier communication output — the standard for the transportation segment — allows more data to be transmitted than an RS-485 output


You would need to use SAE J1939 to decode the actual meaning of the output data. It is possible that Honeywell could provide you more information as part of purchasing the product.

To use this to develop an AHRS solution you would still need pitot &amp; static inputs to derive pressure altitude and airspeed, as you won't be able to get those from the provided sensors.


  acceleration range up to ±6 g, rotation rates up to ±75 deg/s,inclination angles up to ±50 deg and a sensor update rate from 1 Hz to 100 Hz


I think the biggest hurdle you have here is that it will only measure inclination angles up to 50 deg. Aircraft can find themselves in > 50 deg pitch attitudes, which won't be registered by the IMU.

This particular product (Honeywell 6DF-1N6-C2-HWL) seems to be designed for ground vehicle applications rather than aviation.