We should be aware of the possibility that the system works in other ways as it is "software driven" and this kind of software sometimes is modified, up-dated, replaced.
In principle it is thus possible for all units to communicate with each other anytime using the common bus-system.
Errors in the program(s) running in ADIDU units have been detected earlier, often after software up-dates that brought an earlier buried program bug to the surface.
Some links and comments:
ADM example:
http://www51.honeywell.com/aero/comm...ata_Module.pdf
Observed ADIRU problems:
9M-MRG: The ATSB found that the main probable cause of this incident was a latent software error which allowed the ADIRU to use data from a failed accelerometer.
On 6 August 2008, the FAA issued airworthiness directive 2008-17-12 expanding on the requirements of the earlier AD 2003-26-03 which had been determined to be an insufficient remedy. In some cases it called for replacement of ADIRUs with newer models, but allowed 46 months from October 2008 to implement the directive.
The 46-months span the time of the AF447 accident!
Regards and good luck with the structuring work.