- by Dave Butler, CFSE
- Thursday, August 29, 2013
- Software
Software Modeling and Functional Safety: Part 2
Part 1 of this blog entry discussed software modeling, modeling notation, and modeling tools. But, what does this have to do with Functional Safety? The IEC 61508 standard has requirements, for certain SIL levels, regarding the use of:
- “Semi-formal methods”
- Computer-aided specification and design tools
- Design standards
- Performance modeling
…
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- by John Yozallinas, CFSE
- Thursday, December 06, 2012
- Software
Spaces and Braces and Comments – Oh My!
What constitutes a good coding guideline?
Serious software development for functional safety requires a coding standard or coding guideline. Most organizations have one, but how do you know if it’s good?
You need to look beyond the boilerplate and physical code layout that are often defined in a coding…
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- by John Yozallinas, CFSE
- Tuesday, June 29, 2021
- Certification
Spend Your Product Development Time Wisely
Want to improve your safety lifecycle and be more compliant with IEC 61508? Focus on the things that have the most benefit. Like what? What are some of these valuable things?
One of the major deficiencies I see while doing certification assessments is…
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- by John Yozallinas, CFSE
- Thursday, June 19, 2014
- Certification
Stress vs. Strength… In My Process?
I consistently find that with companies who are new to functional safety development, the SW process is not as structured or mature as the HW process. SW development is often more informal, and subject to the interpretation of one or more SW developers. But when project delays occur, it’s…
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- by Dr. William Goble, CFSE
- Friday, March 04, 2011
- Certification
Tales from the Certification Wars - Who certifies the certification agency?
I have often heard the question “Who says they can issue a certification?” This is often accompanied by “Why can’t I certify my own product?” “Who knows our design better than we do?” Good questions.
The IEC 61508 standard does not require certified products for Functional Safety. …
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- by Denise Chastain Knight, P.E., CFSE, CCPSC
- Thursday, August 27, 2015
- Certification
The Architectural Constraint Blind Side
I did my homework, purchased certified devices, and specified physical redundancy. I expected an uneventful SIL Verification but the assessor is telling me that I have functions failing Architectural Constraints in the sensor and final element groups. How can that be?
Low demand mode Safety Instrumented Function (SIF)…
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- by Michael Medoff , CFSE, CISA
- Monday, June 08, 2015
- Functional Safety
The Evolution of Coding Standards
Sometimes it seems that things change slowly in the world of functional safety. If you look at many of the technical references in IEC 61508 you will find that most come from the 1980s and 1990s. There is even one reference that dates back to 1950! With the rate…
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- by Iwan van Beurden, CFSE
- Monday, July 14, 2014
- Certification
The exida Certificate Explained
A manufacturer whose product passes the exida IEC 61508 Assessment Scheme will receive a certificate based on IEC 61508 and perhaps other functional safety standards. There is a significant amount of information on a certificate that may not be always trivial for a novice. This document explains how one…
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- by Dr. William Goble, CFSE
- Tuesday, January 27, 2015
- Functional Safety
The exida FMEDA Process - Accurate Failure Data for the Process Industries
In this blog, I will talk about the FMEDA method and how it can generate realistically accurate failure rate data.
The first question we have to ask is “why do you need failure rate data ?”
One of the fundamental concepts in today’s functional safety standard, IEC 61508 and…
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- by Loren Stewart, CFSE
- Thursday, May 16, 2013
- Certification
The exida Scheme
Today I was asked: “What is the exida Scheme?” If one person had this question, it is likely that others may be interested as well. Therefore, I decided to take a moment and explain the exida structure. Any Certification Body operates each product certification per a “scheme,” which references…
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- by Dr. William Goble, CFSE
- Wednesday, February 27, 2013
- Software
The Real PFDavg Variables
I was recently asked how the PFDavg value in an exida FMEDA report was calculated. Those PFDavg values are calculated using the exSILentiaTM program. The person who posed the question was using the equations from Part 6 of IEC 61508 and got a different value. Why?
exSILentia…
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