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Functional Safety

Structural Source Code Coverage – Cost without benefit?

Structural Source Code Coverage: Are you working in software projects where functional safety is becoming more and more important? The use of IEC 61508, ISO 26262 or a comparable standard is around the corner or you are already in the middle of such a project? In these cases you have probably already encountered the term […]

data- and control flow

Requirement completeness using data- and control flow analysis

Carrying out a data- and control flow analysis is required in almost all functional safety standards (ISO 26262-6 Table 7 Measures 1f/g, DO 178C Table A-7 Measure 8 and EN 50128, EN 50657Table A19 Measures3/4). In comparison to other measures, the data and control flow analysis causes a lot of questions, when it comes to […]

The non-intrusive measurement of structural coverage

The non-intrusive measurement of structural coverage!

The measurement of structural source code coverage is nowadays defined as an important procedure in many functional safety standards. The non-intrusive measurement of structural coverage offers completely new possibilities in the future. For a long time, it was industry-wide consensus that structural coverage should and could only be determined in so-called white-box tests. In many […]

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RTCA DO 331 Model-Based Development RTCA DO 331 Modellbasierte Entwicklung

RTCA DO 331 Model-Based Development and Verification in aerospace

With the enhancement of the RTCA DO178B to the RTCA DO178C, four so-called supplements have also been developed. The RTCA DO 331 Model-Based Development is one of these four supplements and describes the requirements for model-based development and verification in aerospace. The following article provides answers to the following questions: How is the RTCA DO331 […]

Supplements of DO178C

The Supplements of DO178C – Where do they come from and what is their content?

With the enhancement of the RTCA DO178B to the RTCA DO178C, four so-called supplements have been developed. These supplements of DO178C define the conditions under which modern software development methods can be used in aerospace. If you look at the history of the RTCA DO178, you will notice that changes to the standard are rarely […]


RTCA DO 178C – Software quality in aerospace!

RTCA DO 178C – The Myth! As early as 1980 there were first considerations in aerospace how to develop software safely and as accurately as possible. These considerations have led to the development of a standard that is widely respected far beyond software. Currently in the version RTCA DO 178C. The standard is used in […]

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EN50128 and EN50657

EN50128 and EN50657 support tools

EN50128 and EN50657 support tools

Chapter 6.7 of EN50128 and EN50657 support tools and languages defines requirements for software tools that are used in a safety-relevant development process. Project team members in safety projects discuss the content and meaning of this chapter again and again. The following article summarizes the essential requirements and derives a practical guide for use in […]

EN50128 configurable Systems

EN50128 configurable Systems – The solution?

Chapter 8 of EN 50128 specifies the requirements for systems that are configured by application data or application algorithms (EN50128 configurable Systems). This blog summarizes the essential requirements of the standard and the practice-oriented challenges of software-configurable embedded systems. At the first glance the configurability offers only advantages. The functional behavior of the entire system […]

EN50128 konfigurierbare Systeme

EN 50128 Functional Safety in the railway industry

The EN 50128 Functional Safety standard describes together with the EN 50126 and EN 50129 the functional safety in the railway industry. These standards implement the IEC61508 for this industry. The peculiarity of the rail industry with regard to functional safety is that the systems are to be certified by an governmental authority (in Germany […]

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Safety Case

ISO26262 Safety Case – Success factors: management and traceability!

The term Safety Case is used in the automotive industry and railway industry (EN50129). The following article focuses on the automotive industry. Project experience shows that the achievement of a proven functionally safe system is complex and extensive. This is particularly true if the development of a product is spread over several companies. I will […]

IISO26262 ASIL Decomposition

ISO26262 ASIL Decomposition – Pros and Cons!

ISO26262 ASIL Decomposition: Part 9 of ISO26262 defines a scheme for dividing a requirement with a specific ASIL level into two requirements with lower ASIL levels. In the following blog post I will address the question when the ASIL decomposition can be applied in practice and what are the advantages. At the same time, however, […]

ISO26262: Freedom from interference

ISO26262: Freedom from interference – What is that?

ISO26262 Freedom from interference : There are four essential measures in the development of safety-critical systems. Design of safe systems Measures to minimize random hardware errors Measures to minimize systematic hardware and software errors Organizational measures (management of functional safety) Particularly in the design of safe systems, the principle of Freedom from interference is a […]

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Functional Safety Basic Standard IEC61508

IEC 61508 – The Functional Safety Basic Standard

The Functional Safety Basic Standard IEC61508 is often referred to as the mother of all functional safety standards. This standard was introduced in 1998 with the intention of defining cross-industry processes and methods to be used for safety-relevant electrical, electronic and programmable electronic systems. IEC61508 is applied if no industry-specific standards are available for this […]

zertifizierte Werkzeuge, Tool qualification

IEC 61508 – Tool qualification – When? Why? How?

The term tool qualification triggers an unpleasant feeling and uncertainty in many people who deal with functional safety. IEC61508 requires the certification of software tools used for software development. Other functional safety standards also require similar measures. Unfortunately, however, the same terms are not always used. IEC61508 uses the term „certified tools“, often the term […]

IEC61508: Specification – Architecture – Requirements; Is there any difference?

For an increasing number of systems in the industrial automation functional safety requirements must be fulfilled. The IEC61508 compliance must be demonstrated for the software development. On the other hand, there are commercial requirements which often severely limit the product development budget. The solution lies in an efficient development process that meets the safety-relevant requirements. […]

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Other FuSa Standards

ISO 25119 Software Development

ISO 25119 Software Development for Tractors and Machinery for agriculture and forestry

ISO 25119 Software Development: The norm describes the safety requirements for tractors and machinery for agriculture and forestry. The standard is a sector specific implementation of IEC 61508 and consists of 4 parts. Like other functional safety standards, ISO 25119 specifies various levels of criticality. The standard defines the Agricultural Performance Level (AgPL) QM, a […]

ISO 13849 Safety of machinery

ISO 13849 Safety of machinery – Software development

ISO 13849 Safety of machinery, describes the requirements for the functional safety of machines. The safety standards in the field of machinery are divided into Type A, Type B and Type C standards. ISO 13849 is a Type B standard. For machines that are covered by the scope of a Type C standard and that […]

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Requirements Engineering

Requirement and Test Traceability

Requirement and Test Traceability – Any added value?

Requirement and Test Traceability: Think about the following situation: You are near the end of your safety-related project and you have established traceability between all the project artifacts. In an audit (e.g. Internal Quality Assurance, Customer, External Authority) you have to demonstrate which software requirements are developed from which System Requirements. Each software requirement is […]

Requirement Engineering

Requirement Engineering for Embedded and IT systems – It’s time for the embedded community to become aware of the differences!

If you analyses the book market, publications or conferences on requirements management and Requirement Engineering, you will find that more than 90% consider requirements engineering from the point of view of IT software systems. There are very few publications that look at the topic from the perspective of embedded systems. On the one hand, it […]

RE Engineering – Aspects which even not considerd in RE theory!

In most of the requirement engineering publications, the focus is on management aspects. The collection and management of requirements is discussed extensively. In the following blog I discuss important aspects which are not sufficiently considered in the RE theory. I start with the definition of Requirement Engineering in the book „Requirements Engineering Fundamentals“ (Klaus Pohl, […]

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Validation and Verification

Implicit Testing

Implicit Testing – A good idea (Part 2)?

In the first part of the blog I defined the term Implicit Testing and discussed root causes for the need of implicit tests. Now, in the second part I will focus on the disadvantages of such tests and on possible solution approaches with the goal to avoid these disadvantages.

Implicit Testing – A good idea (Part 1)?

In larger safety-critical projects, quite often I hear the following statement: „Well, the Requirement A is indirectly or implicitly proven with the test XY!“ Do you know this sentence as well? Have you ever experienced what can happen in late project phases when you have tested many requirements indirectly? The blog defines the term in […]

Structural source code coverage and Requirements – Is there any dependency?

If you are newly engaged in the area of functional safety, then you will encounter fairly quickly the terms “structural source code coverage” and “requirements”. The specification of technical systems by requirements is, of course, also common in non-safety-critical areas. By contrast, the subject structural source code coverage is almost unknown outside safety-critical projects. In […]

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Config and Quality

Quality Assurance in functional safety projects – Where is the difference?

The quality assurance checks the quality of the product. This is first of all an almost trivial statement. Depending on the definition of the term „product“, however, differentiate the responsibilities clearly. Do we monitor a production process or are we considering the assurance of quality in a software and electronics development? The following blog deals […]

Configuration Management

Configuration Management: A challenging task!

Do you know the following situation? A software project is restarted and the individual tasks are distributed within the project team. Sometime if (nearly) all roles are assigned – no one has thought about the configuration management. Often this role is quickly assigned to the project leader, because – so the assumption -there is anyway […]

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Security for Embedded Systems – What lies ahead of us?

The need for security protection measures in the Office IT environment is obvious since years. Firewall, virus scanner, encryption of data: Office IT is no longer thinkable without these aspects. On the other hand, security for embedded systems is relatively new. These systems are already vulnerable to possible malicious attacks. For a long time there […]

Security – A term that has many meanings!

Security is a topic which plays a key role for the success of topics like Internet of Things, Smart Home. If we consider the topic in more detail, it will be realized that it will be worthwhile, to separate the individual topics. It is important to be aware that the boundaries of the separate topics […]

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