What is specified in IEC-61508 regarding software safety validation?

• A. It is optional but recommended
• B. It is a mandatory step in the safety lifecycle
• C. It should be conducted every five years
• D. It is only applicable to hardware components

Answer: (B)

IEC-61508 outlines a structured approach to functional safety across various industries, including the development of software within safety-related systems. The standard emphasizes that software safety validation is a critical step within the safety lifecycle, making it mandatory. This crucial phase ensures that the software meets the defined safety requirements and performs reliably under all conditions specified.

The requirement to carry out software validation is rooted in the understanding that software can introduce significant risks if not properly validated. By mandating this step, IEC-61508 ensures that all aspects of safety are thoroughly examined and confirmed, contributing to the overall integrity of the safety system. The requirement for software validation is also reflective of the growing dependence on software in safety-critical applications, underscoring the importance of verifying that software operates correctly in conjunction with hardware components to mitigate potential hazards effectively.

In contrast, other options suggest less rigorous approaches, such as making validation optional or restricting its application to specific intervals or hardware components, which does not reflect the comprehensive safety assurance intent of IEC-61508.