Thanks for the reply Dirk and the information on your slave modules. Yes, I was looking for a module to act as a Profibus master on the RPi (so we could avoid having a PLC as the master).

I have just come across your Revolution Pi device. Very nice looking. I was wondering if you have a solution that would allow connecting one or more Profibus DP slave devices (eg, a Profibus pressure transmitter) to the RPi ?