I'd like to poll the status of the MavLink connection between a SBGC (32-bit extended) and a Pixhawk flight controller using the serial API. I just want to duplicate the "AHRS: OK/low rate/no" field in the MavLink connection section of the External IMU tab of the GUI.
It looks to me like this information is encoded in the response to CMD_MAVLINK_INFO (250) but the Serial Protocol Specification does not provide documentation on the payload structure or how to interpret the fields.