A runtime server includes a plurality of simultaneously executing runtime systems, which are configured for real-time execution of a control program for an automation system. At least two of the runtime systems execute application modules of the control program, with at least one module executing an application of the control program being installed on each runtime system. Each runtime system has a data transmission interface for transmitting data between the runtime systems and/or application modules, an I/O configuration which defines an allocation between at least one variable of the application modules and at least one hardware address of a hardware component of the automation system, an I/O interface for data exchange between the runtime systems and hardware components, and an intermediate I/O mapping layer. The I/O configurations are mapped in the intermediate I/O mapping layer.