The invention relates to a real time-capable control system essentially consisting of a software-implemented SPS application that exchanges the output data and input data by means of a field bus connecting module. The SPS application runs on a computer under the control of a non-real time-capable operating system, whereby the full functionality of the non-real-time-capable operating system is maintained. The real time capability makes the field bus connecting module ready for use, and the data are exchanged between the field bus connecting module and the SPS application via the host interface located inside the computer.