Control system for controlling safety-critical processes

A control system (10) for controlling safety-critical processes in an automated system by means of a communications network (20) with:

• an unsecured communications master (22) for controlling the communications on the network (20);
• and
• a plurality of network subscribers (12, 14, 16, 18), wherein at least three of the network subscribers are configured as decentralized, secure network subscribers (16) and each has a separate, decentralized safety controller (17) for controlling a safety-relevant application,
• each of the decentralized, secure network subscribers (16) has a unique safety address,
• each of the decentralized, secure network subscribers (16) executes safety functions or safety logic operations relevant for said subscriber (16),
• the secure network subscribers (16) are grouped into at least three safety islands (1, 2, 3), and
• a logical point-to-point communication (36) via a data line on the network (20) between the decentralized, secure network subscribers (16) is configured as a fail-safe point-to-point communication (36) based on a chain of point-to-point relationships (36) from one safety island to another safety island,
• wherein a decentralized, secure network subscriber (16) of a first safety island (1) in a point-to-point relationship forms a master (32) and a decentralized, secure network subscriber (16) of a safety island (2) that follows the first safety island in the chain forms a slave (33),
• the master-slave relationships between safety islands (1, 2, 3) forming the chain of point-to-point relationships, so that decentralized, secure network subscribers (16) are pairwise individually connected with each other, thus providing each other safety functions.