Safety controller

A safety controller for the safety monitoring of a plant, the safety controller comprising:

• at least one input for connection of a sensor,
• at least one output for connection of an actuator, and
• a communication interface for connection of an upstream further safety controller arranged upstream and a downstream further safety controller arranged downstream in a line arrangement, and to exchange exchangeable control relevant information with the upstream further safety controller and the downstream further safety controller,
• wherein the safety controller further comprises a control unit configured to execute a control program and generate a control signal to the at least one output in accordance with predeterminable logic rules in dependence on at least one of input signals from the at least one input and the exchangeable control relevant information,
• wherein the control program works in self-sufficient manner within the safety controller,
• wherein the exchangeable control relevant information has a global meaning defined via a line arrangement in advance and independent of communication within the line arrangement in the safety controller,
• wherein the control program has logic rules to:
• receive the exchangeable control relevant information from the upstream further safety controller and the downstream further safety controller in point to point communication,
• internally process the exchangeable control relevant information, and
• provide the result of the internal processing to the communication interface for point to point communication to the upstream safety controller and the downstream safety controller,
• wherein control programs of the upstream and downstream safety controllers formed in the line arrangement compare with one another the exchangeable control relevant information upon activation of the safety controller,
• wherein the exchangeable control relevant information is at least part of a pre-defined process image of the safety controller defined independently of the line arrangement in the safety controller and valid in the overall line arrangement, and
• wherein the process image is not modified when adapting the plant, and all of the safety controllers, with respect to the exchangeable control relevant information, are synchronized to the same pre-defined process image.