System having a sensor and a method for monitoring a plurality of protected zones

A system having at least one sensor for monitoring a plurality of protected zones for infringement by at least one object and having a controller for controlling a plant to be safeguarded having a mechanically movable part,

• having the sensor for the at least planar monitoring of the protected zones,
• having a control and evaluation unit for evaluating the received signals of the sensor to determine which of the protected zones has been infringed by the object, called a protected zone infringement in the following, and
• which protected zone the object has left, called a protected zone release in the following,
• having the controller to generate and output a switch signal that is a release signal for the release of the plant operation,
• with the controller being configured to output the release signal when the controller recognizes a predefined order of incidents, with the incidents comprising protected zone infringements and protected zone releases of the protected zones and with each incident being either a protected zone infringement or a protected zone release,
• with the mechanically movable part having a first working zone and a second working zone,
• with the mechanically movable part being either in the first working zone or in the second working zone,
• with a first protected zone and a second protected zone being associated with the first working zone,
• with the first protected zone being adjacent to the first working zone and the second protected zone being adjacent to the first protected zone,
• with the first protected zone only being reachable via the second protected zone,
• with a third protected zone and a fourth protected zone being associated with the second working zone,
• with the third protected zone being adjacent to the second working zone and the fourth protected zone being adjacent to the third protected zone,
• with the third protected zone only being reachable via the fourth protected zone,
• with the controller being configured to start the mechanically movable part when an object has left the first protected zone and has then left the second protected zone, whereby a protected zone release is present in the first protected zone and subsequently in the second protected zone, or
• an object has left the third protected zone and has then left the fourth protected zone, whereby a protected zone release is present in the third protected zone and subsequently in the fourth protected zone,
• with, if the mechanically movable part is active in the first working zone, on protected zone infringements in the fourth protected zone being configured to switch the mechanically movable part into a non-hazardous working mode,
• and, on protected zone infringements in the second protected zone, the controller being configured to stop the mechanically movable part,
• with, if the mechanically movable part is active in the second working zone, on protected zone infringements in the second protected zone, the controller being configured to switch the mechanically movable part into a non-hazardous working mode,
• and, on protected zone infringements in the fourth protected zone, the controller being configured to stop the mechanically movable part.