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What is IEC 61508 & why is it important for embedded software development?

IEC 61508 is an internationally recognised standard for the functional safety of safety-related programmable electronic systems. Determined by the International Electrotechnical Commission (IEC), the IEC 61508 safety standard provides a framework to develop and control safety-related systems. IEC 61508 applies across all industries and sectors such as manufacturing, industrial processes, automotive, and more.

Amongst other things IEC 61508:

  • Defines what’s required to achieve functional safety
  • Provides guidance on the management of functional safety throughout a product’s lifecycle
  • Offers a risk-based approach to determine the necessary safety integrity levels (SILs) for safety functions

What are Safety Integrity Levels? (SILs)

IEC 61508 outlines the concept of Safety Integrity Levels (SILs), which measure the effectiveness of a safety system to mitigate the risk associated with a specific hazard.

The IEC 61508 standard emphasises the importance of systematic methods to achieve functional safety.

Systematic methods to achieve functional safety include:

  • Hazard and risk assessments
  • Safety-conscious system design
  • Rigorous testing of multiple possible scenarios
  • Implementation
  • Operation and maintenance

Many industries that are involved in the design and implementation of safety-related systems use IEC 61508 as the basis to develop their own safety standards. IEC 61508 provides a general framework and specific industries may have their own sector-specific standards that build upon or tailor the principles outlined in IEC 61508 to meet their unique safety requirements.

What are the important steps to develop an IEC 61508-compliant product?

Compliance with IEC 61508 involves a comprehensive approach to managing functional safety throughout the entire lifecycle of a system.

Safety Lifecycle Management:

  • Planning: Establish a plan for the entire safety lifecycle, including defining safety roles and responsibilities, resources, and schedules.
  • Hazard and Risk Assessment: Identify and assess potential hazards and associated risks to determine the required Safety Integrity Levels (SILs).

System Design and Implementation:

  • Functional Safety Requirements: Clearly define functional safety requirements for the system.
  • Architecture and Design: Develop a system architecture and design that meets the specified robust safety requirements and SILs.

Verification and Validation:

  • Conduct thorough product testing: Within a high-safety industry, you should ideally test your component with multiple scenarios.  Your testing process should be rigorous and include simulations that can recreate multiple possibilities. This process should be thoroughly documented to test that the system meets the safety requirements defined in IEC 61508.

Operation and Maintenance:

  • Operation: Establish procedures for the safe operation of the system.
  • Maintenance: Develop a maintenance plan to ensure the ongoing integrity of safety functions.

Verification and Validation:

  • Systematic Capability: Demonstrate the systematic capability of the organization to achieve the required SILs.
  • Functional Safety Assessment (FSA): Conduct a functional safety assessment at key stages of the lifecycle to verify and validate the safety functions.


  • Safety Case: Develop a safety case that documents the safety requirements, analysis, and evidence demonstrating compliance with the standard.
  • Documentation Control: Implement a robust documentation control process to manage safety-related documentation throughout the lifecycle.

Management of Change:

  • Change Management: Establish procedures for managing changes to the system to ensure that safety is not compromised during modifications or updates.

Competence and Training:

  • Competence: Ensure that personnel involved in safety-related activities have the necessary competence and training.
  • Training Programs: Implement training programs to keep personnel up-to-date with the latest safety practices and technologies.

Independence and Impartiality:

  • Functional Independence: Maintain functional independence in safety assessments and activities to avoid conflicts of interest.
  • Impartiality: Ensure impartiality in the evaluation and decision-making processes related to safety.

Continuous Improvement:

  • Performance Monitoring: Implement processes for monitoring the performance of safety functions.
  • Incident and Failure Analysis: Conduct thorough analysis of incidents and failures to identify areas for improvement.

Supplier and Outsourcing Considerations:

  • Supplier Management: If using external suppliers, ensure that they meet the necessary safety requirements. Using trusted suppliers and vetting them properly is important. It’s important to properly verify their credentials and see evidence of their expertise and testing capabilities.
  • Outsourcing: If outsourcing safety-related design, establish where the team are based, previous experience and how they are managed.

Security Considerations:

  • Cybersecurity: Safety systems are increasingly connected. Addressing cybersecurity concerns prevents unauthorized access and potential compromise of safety functions.

When developing a product or component, skilled engineers need to tailor IEC 61508 compliance considerations to their specific industry, system, and operational context.

Why Bermondsey Electronics are ideally suited for IEC 61508-compliant product development

Bermondsey Electronics are a standards-driven and compliance-focused embedded software engineering company. Our team are so focused on testing that we developed our own robust testing system. This enables us to thoroughly test all embedded software development projects we work on with affordable and repeatable testing. Our highly test-driven methodology injects electrical signals into products to see how they behave. Our testing process eliminates one of the biggest sources of errors in production. This results in truly resilient products with safety issues eliminated before they’re deployed.

Our rigorous product development process

Our unique testing process enables our expert testers to simulate a huge variety of electrical states in real life, giving them a test harness that enables comprehensive testing. This makes sure that the component performs as predicted in a wide variety of scenarios and doesn’t throw up errors that could cause safety issues. Our team works with our clients to come up with innovative scenarios of tests to conduct. Our methodology enables the scenarios to be simulated with flexibility and tested quickly. We think of hundreds of different ways that something could break or fail and use software signalling to simulate limitless scenarios. Extensive testing is built right into our highly structured development process and not just tagged on at the end, to avoid creating an integration crunch of faults. Our team work to international project management standards to ensure consistently good results. These include Vcycle, Waterfall, and Agile development principles, all built around our test-driven development methodology.

Our comprehensive testing process reduces the risk of testing safety scenarios

Bermondsey Electronics’ rigorous testing process is especially relevant for IEC 61508 because it enables us to test our clients’ components by simulating dangerous scenarios with no risk to human life.

Examples of safety-focused products that Bermondsey Electronics have rigorously tested:

  • An energy storage unit that becomes dangerous when it stores too much energy. Complex sets of software scenarios simulate multiple outcomes to test the component safely.
  • Fire systems for oil platforms. It’s undesirable to actually set fire to an oil platform to test it.
  • An industrial component with a flywheel that goes out of control. Conducting this experiment in real life could endanger human life, so software testing of multiple scenarios is ideal.
  • Smoke curtain deployment based on logic-driven criteria. Many industries cannot test this equipment in real life due to their operating hours or high volumes of pedestrian traffic.

Specialist IEC 61508 compliant embedded software development experts

Bermondsey Electronics’ strength lies in IEC 61508 compliant development of fully documented safety-critical embedded software for industrial devices. Our rigorous testing process documents how your product meets these stringent safety requirements. Our approach to testing enables you to trust that your components can be used safely and will perform as expected in multiple scenarios within industrial and highly safe environments.

Call our expert team to talk through your IEC 61508-compliant embedded software development project.

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