The majority of fieldbus communications protocols have created an Ethernet version, in most cases by "packaging" their higher Application or User layers inside an Ethernet packet. One widely used standard - at least for the process industry is the HART Communications Foundation and the HART protocol.
Interestingly if you take a look at the changes made to HART from HART 5 through to the present HART 7 the feature list is becoming more and more similar to Fieldbus and Profibus PA. Of course WirelessHART is not a big step from a wireless Ethernet system either, especially as it needs to connect from the gateway to the controller. This therefore begs the question “Is the HART Communications Foundation upgrade to their HART Server the first step towards an Ethernet based version of HART or will the OPC interface be as far as they go?” My guess is that like many other HART specification updates it is only a matter of time until something magically appears to fill this void in their product offering.
More information on the HART Server including several documents describing “how it works” can be found at http://hartcomm.org/hcf/documents/documents_opc.html.