News reaches us somewhat belatedly of one more, hopefully final, compromise in the long saga of the European Safety standard EN 954-11 and its replacement by the European implementation of the relevant ISO and IEC standards, EN ISO 13849-1 and EN/IEC 62061, relating respectively to machine safety in general and safety PLCs in particular.
The standards had originally been scheduled to come into force under the auspices of the European Machinery Directive on December 29, 2009, without any further period of grace for compliance. However, at the beginning of September 2009, the European Commission, under pressure from some machinery builders who had argued that they would be unable to meet the deadline because of a lack of availability of suitable components, or at least of reliability data on them, announced that it was delaying implementation until 2012. That in turn prompted an outcry from those vendors who had got their act together -- they had after all had three years to do so since 13849 had originally been adopted by ISO -- not, you understand, because they'd invested in complying and were hoping to get their money back through a rush to meet the deadline, but because, as Peter Still of Schneider put it, the old standard is "not really rigorous enough to ensure sufficient safety integrity in many modern and complex machines."
Whatever the reason, within a week the Commission had changed its mind for a second time and reinstated the original deadline, although even then it continued to sit on the regulatory fence, saying that it would not make a final decision until early December.
Now we learn from two of the leading vendors, Pilz and Rockwell, that far from enforcing the original deadline, the Commission has extended it, not as originally intended to 2012 but to December 31, 2011. What this means, in effect, is that EN 954-1 will remain in force in parallel with EN ISO 13849-1 and EN/IEC 62061 for 24 months after which they will finally replace it.
However, according to Pilz, that does not necessarily mean that adherence to EN 954-1 will confer automatic compliance with the Directive. In its own release on the subject, the company states that since "several Type 'B' and 'C' standards have been prepared or revised since the listing of EN ISO 13849-1 and EN/IEC 62061 in the official journal's list of harmonized standards under the machinery directive, do not include EN 954-1 as a standard giving presumption of conformity to safety-related parts of control systems. Designers and manufacturers of such machines and equipment will have to select EN ISO 13849-1."
Both Pilz and Rockwell are arguing that machine builders and designers should in any case adopt the new standards as soon as possible rather than waiting until the end of the new period of grace. "In particular," says Pilz, "OEM designers of new machines with a model life of longer than two years should consider adopting the new standards immediately to avoid the cost of re-design, validation and documentation at the end of the transition period."
Moreover Rockwell points out that many global manufacturers already specify compliance with the new standards and that functional safety data is available in multiple forms including a data library for use with the German Institute for Occupational Safety and Health (BGIA)'s SISTEMA calculation tool and a PDF file providing data for manual calculation. "Early adopters not only will move ahead of the competition, but also help better protect workers and machinery," said Rockwell safety market development manager Dan Hornbeck. "These new standards provide functional safety guidance that helps improve safety, efficiency and sustainability -- while reducing development and operational costs."