Safety devices must work independently of operational measurement and control devices; their failure must as far as possible be detected quickly by technical means; the fail-safe principle applies; safety switching should act directly on the control devices without intermediate software commands; on failure the product must where possible be secured; emergency stops must have restart lockouts that need deliberate reset. Control and display units must follow ergonomic principles for the highest operating safety. Devices with a measuring function for explosion protection must cope with foreseeable operating requirements and special conditions, allow checks of reading accuracy and serviceability where needed, and set alarm thresholds with a safety margin well outside the explosion or ignition limits. Software-controlled equipment, protective systems and safety devices must be designed with particular regard to programme faults.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.