Functional safety work connects the risk assessment to the safety-related parts of control systems. The required performance level or safety integrity level must come from the applicable risk assessment and standard. It should not be assumed from the equipment type or selected to make a design appear safer.
Requirements and architecture
Define the safety functions, their initiating conditions, required responses, reset and restart conditions, and interfaces to standard controls. Review architecture, component suitability, diagnostic measures, common-cause considerations, and the stated PL or SIL target where applicable.
Safety PLC and circuit review
Review schematics, safety PLC logic, device selection, feedback paths, muting or bypass arrangements, and interaction with drives and robot controllers. The review looks for gaps between the written requirement and the implemented logic, including what happens during faults, restart, and recovery.
Calculation and verification
Support PL calculations and documented verification using appropriate data and assumptions. Check that the claimed performance is supported by the actual category, subsystem data, diagnostics, mission assumptions, and design details. A calculation does not replace validation of the installed function.
Validation and lifecycle records
Develop or review test procedures tied to safety requirements. Confirm each function under normal operation and relevant fault conditions, record measured results, and identify limitations. Changes to hardware, software, tools, payloads, or application conditions can affect the evidence and require reassessment.
Deliverables
Possible outputs include a safety requirements specification, architecture review, calculation review, logic review, verification records, validation test plan, and open-issue register. The exact scope depends on the project and the information supplied.