The invention describes a closed-loop and /or open-loop control device (13 to 16) for building mangement systems. The computer unit, in particular a microprocessor, is connected with one or more additional modules (12) by way of a local bus (11). The closed-loop and/or open-loop control device (13 to 16) has several interfaces (22, 23) for a network bus (8), in particular a ring network (9). The closed-loop and/or open-loop control device (13 to 16) is connected to a server (3) and/or one or more additional closed-loop and/or open-loop control device (13 to 16) by way of the interfaces (22, 23). The closed-loop and/or open-loop control (13 to 16) includes a communications module or program for each additional module (12). The communications module is designed to control the interfaces (22, 23) of the network bus (8) and the local bus (11), and to process the input and/or output signals of the additional modules (12) in the computer unit, and/or to transmit these signals to another closed-loop and/or open-loop control device (12 to 16) or the server (3).