Defeating guards and protective devices must be detected to allow restoration of safe operation. The following measures may contribute:
Attach fixed guards in such a way that when the fixing parts are loosened the guards will not remain in their protective position.
Interchangeable protective equipment (e.g. material entry safeguarding for different packaging contours): detection by coding
Guards requiring regular opening: the control system is to check whether the position switch is actuated as expected.
Recording of all safety-relevant processes/conditions by machine control system (data logger / black box).