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Denise Chastain Knight, P.E., CFSE

The Architectural Constraint Blind Side

Thursday, August 27, 2015 | Certification | Feed


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) design is verified against three criteria:

  • Probability of Failure on Demand
  • Architectural Constraints
  • Systematic Capability

Probability of Failure on Demand (PFDavg) is a statistical evaluation based on random failure data representing the likelihood that a SIF will fail to perform properly when there is a process demand. Systematic Capability is an evaluation of the potential that SIF will fail…

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Steve Gandy, CFSP

Failure Rate Data: Are You Being Outsold?

Tuesday, August 25, 2015 | Functional Safety | Feed


When speaking with several manufacturers’ sales teams recently, it became very evident that some of these sales people, selling into the Industrial Safety and Controls markets, had little or no knowledge of how their products’ failure rate data compared to their competitors and/or another industry benchmark (such as DOW or OREDA).  Indeed, most of them had never seen their safety manual, let alone know of its existence.  Some of the companies I spoke with were experiencing a problem competing with their competitors who were using lower, more favorable failure rates.  However, these failure rates being offered by the competitors for similar devices were outside process industry realistic ranges and dangerously optimistic.  For…

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Eric Persson, CISSP, CACE

How Cybersecurity is like a Goldfish

Thursday, August 20, 2015 | Industrial Control System (ICS) Cybersecurity | Feed


Oh look! Squirrel!

I am not much of a blogger. I should be but I’m not. This is strange, because I always have plenty to say.

This subject just gets me going so I am writing about it. I welcome feedback and opinions.

I have been in cybersecurity in one form or another for over 30 years, whether it be as the target of the attacks as an IT Manager, or a consultant trying to educate and help client companies with products and services, I have seen the same trend over and over again.

When a company has a realized or suspected a cyber-event, they go into proactive response mode, begin investigating and…

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John Yozallinas, CFSE

Certification and the Environmental Test

Tuesday, August 18, 2015 | Certification | Feed


Functional Safety Assessments (FSA) focus on the relevant functional safety standards that are to be applied to a product in the appropriate industry.  These are standards such as IEC 61511 in the process automation industry, or ISO 26262 in the automotive industry.  And IEC 61508 is like an umbrella safety standard over all of them.  But what about other specification and standards that a product has to meet?  Most of these non-safety specific criteria come from the markets and industries served by the product.  If you make a product that has to work in a harsh environment, you need to design and test for that environment.  Your users want to know that the…

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Ted Stewart, CFSP

The True Meaning Behind Those Fancy Letters on a Signature

Thursday, August 13, 2015 | Certification | Feed


Let me ask you a few questions: Does adding letters after a person’s name make them more important? What did that person go through to achieve those letters? If someone has XYZ after their name and another person also has XYZ after their name, are they equal? Did one of them have more hurdles to jump over than the other?

These are all interesting questions that aren’t asked very often.  Many people see these letters, but do they understand their true meaning?

In the functional safety world there are MANY types of personnel functional safety experts certified by many different organizations that have their own set of “Letters.”  Are they all created equaled?…

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John Yozallinas, CFSE

Back in the Old Days

Tuesday, August 11, 2015 | Functional Safety | Feed


Some time ago, I was involved with embedded software projects using microprocessors that had limited memory, speed, and I/O resources.  All embedded programming was in assembly code.  All memory variables were global; it was too hard to keep track of stack variables.  The hardware design assumed that any technical problems for data acquisition and timing were just Simple Matter of Programming (SMOP).  Most projects used just 1 or 2 programmers (we didn’t use the term “software engineer” in those days).  Programming usually consisted of one big file that was written with a text editor and compiled/assembled with tools from the microprocessor vendor.  That output would produce errors with limited explanation, so we’d go…

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Dr. William Goble, CFSE

Getting Realistic Failure Rate Data - Part 6

Tuesday, August 04, 2015 | Certification | Feed


Over the course of several blogs , I talked about getting realistic failure rate data, where this failure data comes from, and how different methods of failure data analysis compare. I think if you understand this, you will begin to get a very good feel of what it takes to generate realistic failure data. This is a subject I find very important and I hope you will find your time well spent reading this.

In Part 1,  I wrote about the fundamental concepts of functional safety standard for the process industries, IEC 61511. As well as the design phase of the safety lifecycle. In this blog, I will continue with talking about two fundamental techniques that have been developed in…

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John Yozallinas, CFSE

Building a Foundation for an IEC 61508 Development Process

Thursday, July 30, 2015 | Certification | Feed


There are organizations that are small enough to follow an informal or even undocumented process and still produce a product of sufficient quality to meet market needs.  When these organizations attempt to develop a safety product, they inevitably fall short of meeting the requirements of IEC 61508.  A formalized process that is reviewed and approved, along with project phase deliverables, are a major focus of the standard.

It can be hard to get buy-in from the development team…they just want to get something done.  As a starting point, you have to put some infrastructure in place.  ISO 9000 compliance is a good place to start, because a good quality management system (QMS) is…

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Dr. William Goble, CFSE

Getting Realistic Failure Rate Data - Part 5

Monday, July 20, 2015 | Certification | Feed


Over the course of several blogs , I will talk about getting realistic failure rate data, where this failure data comes from, and how different methods of failure data analysis compare. I think if you understand this, you will begin to get a very good feel of what it takes to generate realistic failure data. This is a subject I find very important and I hope you will find your time well spent reading this.

In Part 1,  I wrote about the fundamental concepts of functional safety standard for the process industries, IEC 61511. As well as the design phase of the safety lifecycle. In this blog, I will continue with talking about two fundamental techniques that have been developed…

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Dr. William Goble, CFSE

I Did Not Lock the Car Door

Monday, July 13, 2015 | Industrial Control System (ICS) Cybersecurity | Feed


I was driving one of exida’s top risk experts from Europe to a business meeting. We parked and I locked the car door.  He commented “I noticed you did not lock the car door when you parked at the exida office.” He was right. In an area I do not know, I always lock the car door.  But not always in the exida lot.  He added “A risk analysis will show car theft is a low risk due to random events, but remember cars are stolen by humans. These are not random events as we know them.”  He added “A good risk return on investment analysis would show you should always lock the…

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Dr. William Goble, CFSE

Getting Realistic Failure Rate Data - Part 4

Thursday, July 09, 2015 | Functional Safety | Feed


Over the course of several blogs , I will talk about getting realistic failure rate data, where this failure data comes from, and how different methods of failure data analysis compare. I think if you understand this, you will begin to get a very good feel of what it takes to generate realistic failure data. This is a subject I find very important and I hope you will find your time well spent reading this.

In Part 1,  I wrote about the fundamental concepts of functional safety standard for the process industries, IEC 61511. As well as the design phase of the safety lifecycle. In this blog, I will continue with talking about two fundamental techniques that have been developed…

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John Yozallinas, CFSE

That Could Never Happen! What are the Odds?

Tuesday, July 07, 2015 | Functional Safety | Feed


I often walk through my quiet neighborhood streets on weekday evenings or weekend mornings.  These are the times when I don’t expect much traffic, and my expectations are usually met.  The probability of a dangerous event that would injure me seems pretty low (risk assessment), since I am usually on the sidewalk and any cars are in the street.  However when I come to an intersection, I am constantly amazed how often one of the few moving cars on the street reaches the intersection at the same time as I do (demand condition).  Thank goodness for stop signs and low speed limits (layers of protection relying on operator, but no automatic safety function). …

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Dr. William Goble, CFSE

Can Wireless be used in Functional Safety?

Monday, June 29, 2015 | Functional Safety | Feed


exida just completed certification of a new sensor product that uses wireless communication to signal a safety logic solver of a potential problem.  Shortly after the certificate was posted, a challenge arose:  “How can wireless be used for safety?”  Well, it is different.  A designer must be fully aware of the different time response issues. The system must be configured to fail-safely upon loss of the wireless signal.  The system timeout must be long enough to deal with the redundancy of radio media.  But it is safe.  The protocols have been through careful analysis and will provide a safe message when the signal is good. 

“But what about security? I do not…

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Dave Johnson

Performing a Cybersecurity Risk Assessment as a Component of the PHA

Tuesday, June 16, 2015 | Industrial Control System (ICS) Cybersecurity | Feed


There are three main components of the safety lifecycle: analysis, realization, and operation. We will be taking a look at the analysis phase, particularly related to the cyber industry.

To start, the first thing to do in both safety and security is do a detailed process, hazard and risk analysis of the system. In the case of safety, you should allocate safety functions that will protect against those risks that you have identified and create a safety specification or set of requirements for each of those safety functions that you are going to apply. Once those requirements are in place, the realization phase is similar to other realization efforts, including design and engineering, acceptance testing and installation, and…

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Dr. William Goble, CFSE

Getting Realistic Failure Rate Data - Part 3

Wednesday, June 10, 2015 | Functional Safety | Feed


Over the course of several blogs , I will talk about getting realistic failure rate data, where this failure data comes from, and how different methods of failure data analysis compare. I think if you understand this, you will begin to get a very good feel of what it takes to generate realistic failure data. This is a subject I find very important and I hope you will find your time well spent reading this.

In Part 1,  I wrote about the fundamental concepts of functional safety standard for the process industries, IEC 61511. As well as the design phase of the safety lifecycle. In this blog, I will continue with talking about two fundamental techniques that have been developed…

READ BLOG POST >>