Regular readers of this magazine will be well aware of the seemingly endless twisting and turning on the pathway to a standard truly interoperable fieldbus protocol. It seems the large manufacturers supporting protocol development have invested to the point where there is too much at stake to offer any concessions to a common non-proprietary interface, without a fight, writes Colin Carter.
The IEC (International Electrotechnical Commission) has attempted to force the pace of the process by deciding to ignore the six `no’ votes cast late last year in the vote to approve the FDIS (Final Draft International Standard) documents for the Data Link Layer (DLL) and Application Layer (AL) of the IEC 61158 fieldbus standard. Under the voting system the `no’ votes must be validated to ensure objections are of a technical nature before final approval; a decision not to validate the no votes has been arrived at. Furthermore the Commission has set a timetable for amendment of the technical specifications, which must be submitted by mid October 1999 for a vote by the end of December 1999 – which should lead to the technical specification being adopted as a standard.
AN INTERNATIONAL STANDARD
The possibility of an international standard has been received with an unusual degree of agreement from the fieldbus community. The Fieldbus Foundation has issued a press release welcoming the developments; John Pittman, FF President, said: “The IEC ruling is good news for the global automation market because it eliminates uncertainty with regards to future fieldbus technology investment.” John Beeston of WorldFIP told C&I “We at WorldFIP welcome the adoption of the FDIS as a single IEC standard. There is considerable work to do in submitting profiles by October and we look forward to a conclusion at the end of the year”. Profibus are similarly positive – Klaus-Peter Lindner, Chairman of Profibus International said: “We welcome the compromise to include the necessary supplements for profiles, on the basis of different protocols, to the existing specification. We look forward to working with SC65C to integrate the Profibus protocol into the IEC 1158 Technical Presentation. We have just four months to do this but with goodwill it can be done.”
We look forward to the harmony continuing into the next Millennium!