CENELEC ended a standards war by publishing every rival fieldbus, 'as is', in one composite standard — not by choosing

the problem

French and German fieldbuses (FIP and PROFIBUS) were incompatible but each too successful to abandon, so the committee was deadlocked for years

background

what everyone would do

The conventional escape from a two-camp standards deadlock is to engineer a technical merge — take the best features of FIP and PROFIBUS and write one universal spec. That was tried and failed: the merged draft grew so overloaded it was too expensive to implement in full and would yield incompatible devices in part, and it left the American Foundation Fieldbus contesting the result anyway. Picking either national champion was politically impossible, and waiting for a third winner produced only an eight-year stalemate.

what they saw

The committee's job had quietly changed from picking one correct protocol to formally blessing the reality that many protocols would coexist. CENELEC grasped that a standard's authority could be detached from a single content: what had to be standardized was not the protocol but the decision that no protocol would be discarded.

the move

CENELEC, the European standards body, did not choose and did not merge. Bound by a strict rule that European standards must supersede conflicting national ones, the national committees struck what Max Felser calls 'a remarkable and unprecedented compromise': they compiled every national fieldbus standard 'as is' into one multi-part composite standard, EN 50170, each part a copy of a national specification and a fully functioning system in its own right — P-NET as Volume 1, PROFIBUS as Volume 2, WorldFIP as Volume 3. Every camp got its protocol formally standardized; the market, not the committee, would decide which one actually got used.

why it works

The mechanism dissolves the defeat that created the deadlock. Each camp's reason to fight was the fear that losing meant abandoning years of investment and having its products written out of the spec. The composite standard removes that loss entirely — nobody's protocol is de-selected, so nobody has incentive to obstruct. In exchange CENELEC gets something national bodies depend on: by forcing all rivals 'as is' into one, legally-binding standard, the European rule that European standards supersede national ones actually takes effect, ending the patchwork and the years of stalemate in a single publishable document. The members' threat is inverted into a benefit — the rule that made a unified choice impossible now works for them because the composite IS the unified document.

the payoff

EN 50170 ratified in July 1996; the all-in-one move then scaled to IEC 61158, bundling eighteen rival fieldbuses into one standard by 2000.

where it breaks

It fails where interoperability is mandatory and not just preferable — if the market genuinely needs one common protocol (a single physical medium, one legally required data format), certifying many incompatible options is a non-answer that just passes the choosing cost to every buyer. It also fails when the committee's blessing has real gatekeeping power: if a party can profit from blocking certification entirely, or if a regulator will treat the weight of a 'standard' as endorsement. And it complicates compliance forthwith: with 18 types, a sampler must read IEC 61784 profiles to know which parts actually work together, trading clarity for peace.

what came after

The composite-standard mechanism became the default endgame for fieldbus politics: CENELEC bundled wars continued in EN 50254 and EN 50325, and the accompanying IEC 61784 'profiles' map which combinations of parts form a working system. Felser's closing line captures the philosophy outright: 'It is now up to the market to decide which of them will be used and gain large acceptance... It is not up to the standardization bodies to decide.'

references

1. [1]Max Felser — 'The Fieldbus Standards: History and Structures'University of Applied Science Berne (technical report), 2002felser.ch
2. [2]Sensor Review — 'Fieldbus standard EN 50 170 available from BSI'Emerald Publishing, 1998doi.org

keep it

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