With the introduction of the term Industry 4.0 in 2011, more efforts are being made to integrate IT technologies to automate, digitize and optimize processes. Rolling is one of the most important forming processes in the metal forming industry. In the case of older rolling mills, which are still frequently used today, there is the possibility of upgrading to the Industry 4.0 standard by means of a "retrofitting". A "retrofitting" of a rolling mill makes economic sense if the rolling mill to be modernized still sufficiently meets its requirements and the costs of purchasing a new rolling mill exceed the costs of the "retrofitting". For this purpose, the rolling mill to be modernized is equipped with a sensor system adapted to the condition variables to be measured and suitable software so the data can be collected, evaluated and analyzed. This can be done by digitally depict the process in the form of a “Digital Shadow” (DS) or “Digital Twin” (DT) and the integration into a “Cyber Physical Production System” (CPPS). This master thesis deals with the designing and realizing of a digital twin through a “retrofitting” of the rolling mill at the Chair of Metal Forming at the Montanuniversitaet Leoben. During this master thesis, two concepts for sensor technology and programming are carried out, which will by means of “Proof of Concept” (POC) show that today’s Open-Source-Programming-Languages are mature enough to depict a CPPS. Furthermore, the implementation of one concept is realized in order to bring the existing rolling mill system up to the state of Industry 4.0.