I’ve heard this phrase so many times in my life… “<Something> is the best thing since sliced bread.” I personally can’t remember a time when sliced bread was not available, but I certainly remember going to the deli and having them use the slicing machine before handing me a bag of sliced rye bread. Slicing soft bread into thin slices by hand is not easy; it’s time-consuming, requires some skill, and involves a number of dependencies (the size and texture of the loaf, size and condition of the knife, etc.) I often wonder, what was the best thing beforesliced bread? The printing press? The wheel?

Well, let’s turn to technology for a moment. We’ve seen it change our lives in so many ways in the past 100 years, and usually for the better. Bread-slicing machine (1928). Transistor. Microprocessor. RADAR and LIDAR. WiFi. All of these allow us to do things faster, smarter, cheaper. But behind every use of technology is the reason to use it in the first place: how will it be applied and how safe will it be?

Designing products for safe use is one thing, but designing them for functional safety is another. In the first case, I want to make sure my water heater is insulated so I don’t get burned if I touch it. In the second case, I want to know that my water heater will turn off the fuel if there is no flame to ignite it. The functional safety product has to gather enough information to determine if a risk is too great, and then achieve a safe state for equipment under its control. And its design has to consider that random and systematic failures may occur when the need for a safe state occurs…the dreaded ‘probability of failure on demand.’

Designing for functional safety without any tools is like slicing the loaf of bread by hand; if you’re very careful you can do it, but it will take longer, it won’t be easily repeatable, and it may not be capable of all the fault detection nuances needed. Conversely, designing for functional safety with a tool like exida’s ARCHx™ (Architecture Design Analysis) is like using the bread slicer: it produces neat, trim slices that you can peel away to detect many of the hidden defects lurking in the design. 

It is extremely important to identify potential design problems as early as possible. Performing an architecture analysis allows designers to:

  • avoid potential random and systematic faults the system may encounter throughout its lifecycle;
  • determine how the system will respond to faults to ensure intended operation of the system;
  • determine potential design mitigation measures for fault control and fault avoidance.

ARCHx is used to perform and maintain architectural analysis for critical systems, especially those being designed to meet IEC 61508 and/or IEC 62443 (cybersecurity, for the curious). It provides a platform to capture high-level designs using a visual tree-based structure that separates the design into three levels of analysis:

  • Units – The classification of elements of the design and its design intent. This can be decomposed into lower level subsystem units to whatever level is required to comprehensively document the design intent.
  • Deviations – The likely and possible failure modes. Each unit is evaluated to determine the impact of potential deviations from its design intent, including its criticality level.
  • Mitigation Measures – The measures to be built into the design to prevent or detect each potential deviation that was identified, including the proper level of effectiveness needed.

What good is finding design flaws if you don’t do anything about them? ARCHx includes action items that can be assigned to any Unit, Deviation, or Mitigation Measure to document any follow-up activity that should take place and who is responsible for it. The tool provides exida’s expert knowledge assistance with content-sensitive suggestions for known deviations and mitigation measures for many common architectural building blocks, which reduces development time, decreases the likelihood of missing fault modes, and improves the quality of the architecture analysis. ARCHx can also import nearly any kind of document (text, spreadsheet, drawing, photo notes from whiteboard discussions, and more) to support the analysis. It also generates reports to assist, guide, and verify completion of a design that is compliant with the planned architecture.

Like the bread slicer, ARCHx leaves no crumbs to clean up, is repeatable and reusable, and saves a lot of time. Maybe I’m biased, but this tool seems like the best thing since sliced bread to me.  Go here and see what I mean.

Tagged as:     software     John Yozallinas     IEC 62443     IEC 61508     archx  

Other Blog Posts By John Yozallinas