If I hear something repeated often enough, it finally starts to sink in. I wish the same could be said for my kids. No matter how many times I tell them to shut off the lights or television before they leave the room, nothing changes. But I digress.

In my case, I'm referring to the IEC 61508 standard. Recently I've talked to countless vendors -- both on the hardware and software sides of the equation -- who are supporting it, and they do so with a chip on their shoulders, as if it's a badge of honor. This caused me to dig into this standard a little deeper, to find out what it's really all about.

What I found was that while the standard is new to some, it actually dates back quite a few years. For industrial applications specifically, IEC 61508 is a key safety measure. It's also claimed international exposure.

Also known as Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems, IEC 61508 is intended to be a basic functional safety standard that's applicable to all industries. Specifically, it defines functional safety as part of the overall safety relating to the equipment under control, or EUC, and the related control system. Functional safety is also the detection of potentially dangerous conditions that might activate a protective or corrective measure to prevent hazardous events from occurring. For these reasons, functional safety relies on active, as opposed to passive, systems.

What's interesting is that the standard covers the complete safety lifecycle, which consists of 16 phases, all of which are concerned with the system's safety functions. What's covered closely in the standard are the concepts of risk and safety. "Risk is a function of frequency (or likelihood) of the hazardous event and the event consequence severity. Risk is reduced to a tolerable level by applying safety functions." It states that zero risk can never be reached, safety must be considered from the beginning, and non-tolerable risks must be reduced. Certainly sounds logical, right?

LDRA, an automated analysis and testing tools vendor that I met with recently, says its customers are requiring compliance with IEC 61508, particularly for the electrical/electronic/programmable electronic (E/E/PE) systems used in industrial automation applications.

Part 3 of the standard covers the safety software lifecycle, including phases like planning and development, which is where LDRA fits into the equation. The processes that require a close watch include requirements traceability, software design, coding, and software verification and validation. Part 3 also applies to any software forming part of a safety-related system or used to develop a safety-related system. This incorporates support tools such as development and design tools, language translators, testing and debugging tools, and configuration management tools. LDRA's tool suite provides comprehensive requirements traceability, source code analysis, structural coverage, and unit testing facilities to help developers comply with IEC 61508.

To help vendors with compliance, the 61508 Association is a cross-industry group of organizations with an interest in achieving a dependable and cost-effective method for demonstrating compliance with IEC 61508 (and other related standards). The purpose of the association is to serve the interests of its members by promoting the proper use of IEC 61508 and related standards and helping them to fulfill their functional safety responsibilities in the most cost-effective manner.

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