Error-free control programs by means of graphical program design, simulation-based verification and automatic code generation

Currently the formalisation in the process of creating automation control programs starts with the programming of the real-time controller. But inconsistencies in the requirements definition and misinterpretations will lead to errors in the program which have to be resolved through expensive software-in the-loop and field tests. This paper introduces a holistic approach for the formalisation of the control design already in the design phase. It also illustrates the design flow for the model-based creation of error-free control programs. Created by means of graphical editors the system definition, which includes the control algorithm, is transferred into Modelica code and thus the executable system model is used for the simulation-based verification. The simulation results are compared to the requirements. Once these are fulfilled and no further errors found, program code for the real-time controller is generated automatically. In this paper Structured Text for programmable logic controllers (PLCs) according to IEC 61131 is generated. In final software-in-the-loop tests the real-time capabilities of the control program are validated.