The invention relates to a control system (100, 101) for controlling safety-critical and non-safety-critical processes and/or system components. The system comprises at least one control unit (1) which is designed to control non-safety-critical processes and/or non-safety-critical system components, at least one safety control unit (2) for controlling safety-critical processes and/or safety-critical system components, and at least one input/output unit (11, 21) which is connected to the first control unit (1) via an internal input/output bus (B2), wherein the control system (100, 101) is designed to operate as the communications master or as the communications slave, or as both, in combination with other devices connected via a fieldbus (FB), and wherein the control system also comprises a master communications coupler (5) and a slave communications coupler (6).
