22.—(1) Safety devices shall function independently of any measurement or control devices, or both measurement and control devices required for operation.
(2) As far as possible, failure of a safety device shall be detected sufficiently rapidly by appropriate technical means to prevent dangerous situations from occurring.
(3) The fail-safe principle is to be applied in general.
(4) Safety-related switching shall in general directly actuate the relevant control devices without intermediate software command.
(5) In the event of a safety device failure, equipment or protective systems or both shall wherever possible, be secured.
(6) Emergency stop controls of safety devices shall, as far as possible, be fitted with restart lockouts. A new start command may take effect on normal operation only after the restart lockouts have been intentionally reset.