Profibus slave device programming?

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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
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Re: Profibus slave device programming?
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IIRC the older profibus runs at 1Mbps and the newer at 12Mbps and I
don't think it uses the standard uart protocol.

Our first profibus-dp product used a cots profibus <-> rs232 board,
requiring only software for the 232 side to communicate with our device.
When we started a project to implement profibus-dp onboard, we decided
to use the SPC3 asic, which handles the lower level parts of the

Sadly this project was canceled before it was completed. But I do
remember it required a fair amount of software even though we used the
SPC3. And had we completed it, we would still have needed to go
through the cerification process before being allowed to sell it as
a profibus-dp product.

I'm not sure if we had the complete spec. All this was over 5 years
ago, so things could be different now.


Re: Profibus slave device programming?
On Sat, 18 Oct 2003 23:16:42 +0000,

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Profibus-PA is not compatible with ordinary UARTs, but Profibus DP is
standard asynchronous characters over RS-485, so I do not see why a
standard UART would network. Older Profibus-DP devices operated at
various speeds up to 1.5 Mbit/s, while newer also support 3, 6 and 12

The problem in software implementations is the requires response time
from the poll, so at least the higher speeds are out of the question.
I haven't seen any certified software implementations, but at least
some Profibus analyzers seems to be available, that are implemented in


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