Dynamic process simulation is of great importance for process controlling. Having a model of the plant can give valuable information during construction, allow for offline testing and tuning, as well as opening doors for more advanced control methods. This thesis work has concentrated on making a fully functional model of a mobile test rig, constructed for the purpose of resembling a typical application of ABB’s IndustrialIT. The test rig consists of a simple water circuit with three tanks, pipes, valves and field devices, allowing for full control of the process from an operator station. Using the commercial software Dymola, along with a newly developed Modelica-library, called Modelica_Fluid, a set of models are created to replicate the dynamic behaviour of all the individual parts in the system. These are constructed based on purely physical relationships, and later joined together to form the complete model of the set-up. The model is then integrated into ABB’s Process Portal A (PPA) environment, and can be run in real-time, accessing true data from a server. This set-up enables the model to act like the actual process from an operator’s perspective. Using the same station, the operator can for example, instead of affecting a real process-instance, change a parameter in the model and retrieve similar results, presented in the same way as real data would.