Topics / Standards and assurance
IEC 61508 software evidence starts with the safety function.
Identify the allocated software obligation and the conditions under which it must hold. Then connect the design, implementation and evidence to that claim.
Keep the software part in the system context.
IEC 61508-3:2010 addresses software requirements within the functional-safety framework for electrical, electronic and programmable electronic safety-related systems. It includes software lifecycle and supporting-tool considerations.
Source: IEC: IEC 61508-3:2010. Scope and edition reviewed 3 October 2026.
The relevant integrity requirements and lifecycle obligations follow the actual system and project. A generic software report cannot establish a safety integrity level.
Make a safety-related change reviewable.
Illustrative example
A threshold update changes the response boundary.
A proposed change alters when a protective action is triggered. The review needs the approved threshold, measurement assumptions, treatment of invalid input and timing behavior. Testing only a normal value on either side leaves boundary and failure conditions unexplained.
| Record | Purpose |
|---|---|
| Allocated requirement | Names the software contribution to the safety function |
| Assumptions and failure conditions | Defines the scope of the claim |
| Verification evidence | Shows what was checked on which version |
| Residual gaps and decisions | Preserves what is not yet established |
Connect the evidence, retain the authority.
Proof’s requirement graph can organize the relationships among software obligations, hazards, implementation and checks. Use it to reduce evidence reconstruction and make missing support visible.
The safety lifecycle, assessment and any tool-use justification still need to meet the applicable project requirements. Start with a bounded record and have the responsible safety reviewer inspect it.
Try it on your software
Choose one safety-related software change.
Bring its allocated requirement and the evidence your safety team needs to inspect.