Self-Test Library

Efficient Self-Test Library

Improving the safe failure fraction of your safety critical system with a solid Self-Test library.

Functional Safety

Solid Library for Efficient and Safe Online Self-Tests in your Project

Background on Online Self-Tests

When looking on all potential failures of a safety system caused by a random hardware fault, we identify general types of failures:

    • λ_s = Failures which don’t influence the safety function (safe failure)
    • λ_d = Failures which influence the safety function (dangerous failure)
    • λ_tot = Total number of possible failures = λ_s + λ_d

For each hardware component, which is part of the safety function, the rate for failures is given with a unit, called failure in time (FIT) and is equal to 10e-9/h.

The FIT rates are available from the hardware vendors or from standardized databases (e.g. SN29500). Furthermore, chip vendors addressing the safety market provide the FIT rates for their internal microcontroller blocks like RAM, FLASH, Clocks and CPU. Due to the fact, that it is impossible to decide in general which failure is dangerous and which failure is safe, we split the FIT rates to 50% dangerous and 50% safe.

For a system with a given safety integrity level, the rate of dangerous failures is limited. This limited rate is given as safe failure fraction (SFF) and depends on system architecture and complexity of the used hardware components. This SFF is the relation of safe failures to all possible failures. The relevant range for a system starts from >60% and rises up to >99%.

Safe Failure Fraction
Safe Failure Fraction (SFF)

To achieve this limit for a system using a complex hardware unit like a microcontroller, we need to enhance the system with online diagnostic (also called "online self-test"). Depending on the algorithm and measure of the diagnostic module, we achieve a defined diagnostic coverage (DC). The definition is part of the safety standard and classified in three classes to simplify the use:

  • low : diagnostic coverage is 60%
  • medium : diagnostic coverage is 90%
  • high : diagnostic coverage is 99%

With this diagnostic coverage, we are able to guarantee that we handle all detected dangerous failures in a system specific way. So that no influence on the safety function is guaranteed. Finally we can calculate with:

  • λ_dd = Detected dangerous failures = DC * λ_d
  • λ_du = Undetected dangerous failures

the safe failure fraction to:

  • SFF = (λ_s + λ_dd) / λ_tot

Extensive Experience in Realization of Online Self-Test Algorithms

One Functional-Safety-Engineer in every team

We continuously educate engineers in software development for Functional Safety. After at least 5 years of activity in this functional safety, the training leads to an examination by an external company. The recognition of the knowledge takes place with the certificate "Functional Safety Engineer".

We are able to contribute a lot of experience, knowledge and technologies from more than 270 projects and research projects to your project.

Mentoring and Training

We support your project from concept inspection to certification by an independent approval body. At all stages we can contribute with experience, tips and tricks to ensure the success of the project.

Certified Solution

You get source code of the self-test algorithms, including all artifacts you will need for approval by the certification authorities. We are happy to integrate the documentation artefacts into your existing process model.

Guarantee and Trust

We are committed from the very beginning to your project and provide you with full support for the realization of your vision. Driven by the enthusiasm of the team work and the fun on the joint success of your project.

Self-Test Library

Individual selection of algorithms and measures for your project guarantee optimal runtime behavior. Prepared are Online RAM-Tests, ROM/FLASH-Tests, Clock-Tests, CPU-Tests, Program Execution Checks and more.

Experience the integration of our team, based on partnership

Safety Critical Software Development

Benefit from our experience in your development. Achieve thus safety and reliability in the implementation of your idea up to the certification by an accreditation body.

Outsourcing Self-Tests

You can lower pressure on your team by outsourcing the development of self-tests to an experienced partner. A detailed and personal delivery guarantees seamless integration into the overall system.

Flexibility and Responsibility

In a normal projects, there exist situations where it is necessary to react flexible and creative. We will find a winning solution and you can always rely on our responsibility for the success of your project.

Innovation und Freedom

We are convinced that a work environment with freedom and transparency is particularly suited to create innovations. We live this way of work every day and would like to impress you with the results.

Projects with ABB according to IEC 61508
Projects with AgaMatrix according to IEC 62304
Projects with AGCO according to IEC 61508
Projects with Airbus according to DO-178C
Projects with Autoliv according to ISO 26262
Projects with BMW according to ISO 26262
Projects with Bosch according to ISO 26262
Projects with Danfoss according to IEC 61508
Projects with EADS according to DO-178C
Projects with Elobau according to IEC 61508
Projects with GE according to IEC 61508
Projects with Grundfos according to IEC 61508
Projects with IFM according to IEC 61508
Projects with Panasonic
Projects with Philips according to IEC 62304
Projects with Samsung
Projects with Schneider Electric according to IEC 61508
Projekte with Sick Stegmann according to IEC 61508
Projekte with Siemens according to EN 50128
Projekte with Trumpf Medical according to IEC 62304
Projects with Valeo according to ISO 26262

You are Interested in Functional Safety ...

Arrange an expert meeting

We offer a free and non-committal interview with one of our experts. We can get to know each other, answer your open questions and also discuss the first requirements of your project.

Related Products and Services

The so-called Flexible Safety RTOS is the real-time kernel with memory protection, pre-certified for applications in the field of functional safety according to IEC 61508, ISO 26262 and IEC 62304

For a first impression of the nature and extent of completed projects, we have put together a small selection for you. For more details read: Reference Projects.