ISO 13849-1 (2015) “Safety-related parts of controls systems – Part 1: General principles for design” is currently in revision under Work Group 8 of ICO/TC199. This standard specifies machine control system functional safety performance levels.
In a recent email, U.S. Tag Administrator Dan Felinski broke down what this revision means. Below is that email – edited for length – and his request for manufacturer feedback.
“There is more detail concerning the substance of the issue contained in the attached memo (which can be shared) but in essence, with the current revision of ISO 13849 (which is a widely used standard on functional safety of control systems that describes architectures to achieve required Performance Levels), they are intending to remove an exception in the current published standard which allows for some design flexibility.” The memo specified: “Where the probability of occurrence of a hazardous event can be justified as low, the PLr may be reduced by one level.” Felinski continued: “We anticipate that the removal of this exception might possibly have a negative impact [on] you and/or your members. In order for us as a national body representing U.S. interests to register a position in support of keeping this design exception in the standard, we need to try and find manufacturers who:
are using PLrs now;
are, or may be considering the use of this allowance;
would object to its removal; and
are willing to assist to reverse it by providing us with at least some idea of your support for a U.S. position, and better yet, some cursory or even anecdotal information to that effect.”
Please contact Dave Felinski firstname.lastname@example.org with feedback and comments.