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Electrical, electronic or programmable systems performing safety related functions are often developed to the IEC 61508 standard. IEC 61508 is the standard governing functional safety of programmable electronic systems. This standard developed by the International Electrotechnical Commission (IEC) is well-established in the industrial process-control and automation industry and is also used in automotive, heavy machinery, mining, and other fields where safety and reliability are critical.
Ensuring Complete Industrial Embedded Systems Testing
Ensuring predictable embedded systems operation for IEC 61508 certification requires knowing you tested 100% of the code. VectorCAST/Cover collects coverage information throughout system test activities and lets you determine adequacy of the system tests.
More testing may then be instituted for those areas of the application.
Why System Testing Isn't Enough for 100% Reliability
System testing will not result in 100% coverage, as many functions contain error handling code that is difficult or impossible to stimulate using the fully integrated application.
The optimal solution is performing unit and integration testing using VectorCAST/C++ or VectorCAST/Ada.
How VectorCAST Assists Certification for IEC 61508
The standard presents a lifecycle approach including risk assessment, design, integration, testing, modification and maintenance and safety management.
The IEC 61508 complete standard is comprised of 7 parts. Part 3 defines the software requirements and sets the safety lifecycle for software, including validation and verification. The safety lifecycle begins with a risk analysis to determine the Safety Integrity Level (SIL) required. SIL is a quantification of the magnitude of risk reduction required.
|SAFETY INTEGRITY LEVEL||PROBABILITY OF DANGEROUS FAILURE PER HOUR||RISK REDUCTION FACTOR|
|SIL 4||>=10-5 to <10-4||100,000 to 10,000|
|SIL 3||>=10-4 to <10-3||10,000 to 1,000|
|SiL 2||>=10-3 to <10-2||1,000 to 100|
|SIL 1||>=10-2 to <10-1||100 to 10|
Based on the risk analysis, the following recommendations are made with respect to source code verification.
IEC 61508 Recommendations for Code Verification
(R = Recommended, HR = Highly Recommended)
|TECHNIQUE||SIL 1||SIL 2||SIL 3||SIL 4||VECTORCAST|
|Dynamic Analysis and Testing||R||HR||HR||HR||VectorCAST/C++/Ada|
|Software Complexity Metrics||R||R||R||R||VectorCAST/C++/Ada|
For software systems, IEC 61508 suggests following a V-model development process. The V-model shows the necessary connection between requirements and validation throughout the entire development process. The VectorCAST tools are used during the verification and validation phases, and during the coding phase as depicted in the graphic below:
The VectorCAST IEC Certification Kit for IEC 61508 and ISO 26262 provides documentation, certificates, and templates that help you use VectorCAST on projects based on the IEC 61508 and ISO 26262 standards.
The kit includes certificates and reports from certification authority TÜV SÜD that are based on documented, application-specific verification workflows. The VectorCAST IEC Certification Kit offers organizations the required evidence to demonstrate compliance with IEC 61508 and ISO 26262.