The invention relates to a control system for controlling safety-critical and non-safety-critical processes and/or system components, which has preferably a modular design, comprising at least a first control unit (1) provided for the control of the non-safety-critical process and/or the non-safety-critical system components, at least one input/output unit (11), (21), which is connected to the first control unit (1) via an internal input/output bus (B2), and at least one communication coupler (5), (6), which is connected to the first control unit (1) via an internal coupler bus (B1) and/or can be connected to additional remote units (7), (8) via a field bus (FB). In the control system according to the invention, at least a second control unit (2) for controlling the safety-critical process and/or the safety-critical system components is provided. In order to provide the safety-related functions, the second control unit (2) comprises at least two processors (22a), (22b) and a first dual-port RAM (DPR1), wherein only one of the two processors (22a), (22b) is connected to the first dual-port RAM (DPR1), and the second control unit (2) communicates with the first control unit (1) via the first dual-port RAM (DPR1) and the internal coupler bus (B1), and the first control unit (1) transmits the data from the second control unit (2) to the communication coupler (5) via the internal coupler bus (B1) and an additional dual-port RAM (DPR2) integrated into the communication coupler (5).