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modbus to profibus conversion.

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Full Member level 3
Jul 19, 2004
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Hi friends pls give an idea about modbus and profibus. Im in search of a modbus to profibus converter idea, im planning to do it with pic micro controller, which pic is suitable for this project? any sample code in C is available? pls help.

Thanks in advance.

- As the most simple point, you'll need a PIC with two UARTs, some newer PIC18 chips have it. For higher PROFIBUS speeds, a PIC24 or dsPIC may be more appropriate.
- You should become clear about what kind of PROFIBUS device you want to design, e.g. a DP slave? What's the intended functionality?
- You most likely won't be able to support the full range of PROFIBUS baud rates in software. Industrial PROFIBUS controllers are mostly using dedicated hardware interface chips like these Overview ASICs: profichip GmbH - automation in silicon
- PROFIBUS is quite complex, I'm curious, if you'll find ready to use C code
- Nevertheless it's feasible, I think. But don't underestimate the effort.

i dont know if you want to build it on your own or have or want a readymade converter.... its not an easy task for the hardship i faced in developing them...

Are you sure you want to develop the stack and develop it... i may advice you to go for a ready made one...

---------- Post added at 21:37 ---------- Previous post was at 21:34 ----------

codes cannot be shared... :(

codes cannot be shared...
Yes, at least those developed in the course of commercial projects. Academic and free software of course can.

You'll find some basic documentation and code for PROFIBUS layer 2 (FDL) protocol handling along with the libnodave project at There may be other projects as well.

I have build modbus protocol on PIC, but not yet for profibus.
Even, I take long time to do modbus, I sure need more time to do profibus. This is example modbus. Next time I will doing profibus.

Thank u friends for ur valuable advices, i jus need to develop a protocol stack for modbus to profibus converter. if a dedicated chip for modbus and profibus is available then it would be easier i think. pls share more information abt it .
Code i asked not for the commercial purpose, its just to know in what way it has to be done, just for the learning purpose. I know the code cannot be shared for commercials.
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YOu won't need a dedicated chip for Modbus, because it's using low baudrates and the protocol is rather simple. I gave a link to an my initial answer. As said, the intended functionality on the PROFIBUS side matters. Is it DP slave, DP master or something else?

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