exida explains Blog

Entries tagged with: Dave Butler

  • by Dave Butler, CFSE
  • Tuesday, June 25, 2013
  • Software

Allocation vs. Derivation

Please see the first entry of the Requirements Management blog series here.

The concepts of allocation and derivation are sometimes misunderstood when it comes to requirements management.  This can lead to confusion and even to safety problems.  The process of derivation involves the writing of a new requirement, …

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Comparing the IEC 62443 Software Engineering Process to IEC 61508: Where Do They Overlap?

Comparing the IEC 62443 Software Engineering Process to IEC 61508: Where Do They Overlap?

With the appearance of malware and nation state attacks on Industrial Control Systems (ICS), such as the Stuxnet (2010), Industroyer (2016) and TRITON (2017) attacks, the IEC 62433 standards are gaining wider attention.  

While the potential targets to attack in an ICS system are many-fold, one plant asset that…

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I have just one more, small change…

How many development teams have heard those few, innocent words uttered from Marketing/Management toward the end of the development phase of a project, only to have their schedule blown out of the water?  The phase of development into which the change is introduced determines the size of the concentric…

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  • by Dave Butler, CFSE
  • Tuesday, August 27, 2013
  • Software

Software Modeling and Functional Safety: Part 1

Mechanical CAD and electronic schematic capture tools have been around much longer than graphical software tools.  This is primarily because physical objects are more naturally represented as components in a computer-aided design program, and it was more obvious how to design those technologies at the time. The “soft” in…

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  • 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 Dave Butler, CFSE
  • Wednesday, July 10, 2013
  • Software

Tracing and Validation Test Planning

Please see the first entry of the Requirements Management blog series here

Please see the second entry of the Requirements Management blog series here

So, you have a set of detailed safety requirements.  You have derived them down to a level of detail you feel spells out…

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