as long as i know there is no way we could build s7 300 mpi cable. just have to buy it from siemens. it is not just a h/w converter, it is also have some protocol inside it. if anybody know how to build one please share with us, many will thank you
dont spend your time for this case. i have searched it for few years but the only thing that i have understood is that the mpi caple software and hardware is a top secret for siemens , by the way if you are insisting on it see the following link for some library and information about mpi cable: http://libnodave.sourceforge.net/index.php
you may found some other resources if you search the web although none of them wouldn't give practical information for communicating with s7 300/400.
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