State of play [fieldbus technology]

It is unfortunate, to say the least, that the search for a common fieldbus standard has proved both protracted and divisive. The fieldbus approach to inter-device communications in a control environment has clear benefits. Costs are lower-the result of replacing multiple point-to-point links with a shared bus-while local intelligence enhances the functionality of field devices and reduces the demands on central computing. For the present, the great majority of fieldbus installations are based on single-link networks, but, as we move increasingly to multi-link networks, with multiple single links connected by gateways and bridges, additional performance gains are being realised. In particular, fault damage can be confined within the originating link, bus power requirements can be distributed independently across individual links, and bandwidth demands can be reduced by confining local traffic to local links. Multi-link networks also allow the characteristics of individual links to be tailored to address specific local requirements, such as high-speed communication or safety-critical design. These are all facets of the benefits available from distributed systems composed of multiple intelligent devices and made possible by fieldbus technology.