Which of the following is NOT an element of Safety Related Parts of the Control System (SRP/CS)?

• A. Human-Machine Interface (HMI) Safety Visualizer
• B. Safety Controller
• C. Safe Diagnostic/Fault Management
• D. Safety Sensor/Actuator Interfaces

Answer: (A)

The safety-related parts of the control system are the components that actively implement and maintain the safety function, including monitoring and fault handling. A safety controller is the brain that runs the safety logic and makes decisions to keep the system in a safe state. Safe diagnostic and fault management continuously checks for faults and initiates actions to prevent unsafe conditions. Safety sensor/actuator interfaces provide the secure channels through which signals enter and exit the safety logic, ensuring that sensing and actuation are performed in a way that preserves safety.

The HMI Safety Visualizer, while useful for operators to see safety status and diagnostics, does not itself perform safety-critical actions or carry safety-rated logic. It serves as an information display and interface, not a safety function provider. Therefore, it is not considered an element of Safety Related Parts of the Control System.