Profibus slave device programming?

I would like to make a Z-World embedded SBC with a Rabbit core behave like a Profibus slave device to a PLC. I don't know if I should shell
out over $1200 for the complete set of Profibus specs since I don't even know if the job is doable on short notice. The SBC has an RS-485 port, but no Profibus stack, so I thought I would program it myself from scratch. Does anyone have any insight into programming an SBC to implement a simple subset of the Profibus DP or PA protocol?
-Robert Scott Ypsilanti, Michigan (Reply through newsgroups, not by direct e-mail, as automatic reply address is fake.)
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address is fake.)

I don't know if anyone has done it with a normal uart as there is a 32 bit CRC and hamming error correction that takes place. We use a SPC3 or VPC3 Profibus DP slave interface chips. These chips is probably not on your SBC. These two chips make programming a Profibus DP slave easy as the chips take care of most of the state machine and buffering. It took one of our guys 2 weeks to do the first Profibus DP slave. The second one a few days. We bought a Profibus DP developer's kit to do the first system. It came complete with Profibus DP source code for a 8051 and a 8051 SBC to run it on.
I would think hard about a PC104 CPU and SST Profibus DP interface card but that would probably cost too much.
Peter Nachtwey
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