Profibus is driven by a serial output, Tx and Rx from the processor. There are several of these ports available on the expansion header, so I see no issue in the BeagleBone supporting Profibus. There is also a CAN port on the expansion header as well, but you will need to provide a driver for it.
Yeah -- the TMDXICE3359 has the PROFIBUS firmware in one of the PRUs
for various modes of operation (DPV0 & DPV1 in both slave and master
modes, iirc). I guess that the question really boils down to how
tough it is, in principle, to take the stack code and bake it into the
Angstrom build -- with the PRU stuff being the most ticklish part of
the question.
I do have the TMDXICE3359 on order ($99 and free shipping). I'm not
sure what the specs are on memory etc. It seems to run an ad-hoc
kernel of some sort.
If I do manage to bake some of the various industrial protocols into
the Angstrom build, I'll post a little "how to".
Sure do like these AM335x chips, though -- they seem perfect for
process control applications.