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The discrete manufacturing domain is characterized by a strictly hierarchical structure of the automation systems, commonly referred to as the automation pyramid. Data acquired by a sensor typically flows through an IO-module into a Programmable Logic Controller (PLC) which manages the local real-time control system. As all process data are concentrated in the PLC, re-programming the PLC and thus, implementing interfaces to access these data appear to be the natural choice to transfer them to the IT system. However, for brownfield installations this choice has proven impracticable for the following two reasons:In brownfield facilities, PLC usually operate within a once-specified environment and are rarely re-programmed. That is why the active staff is often not familiar with the code and lacks of the competence to modify the existing implementation in a reasonable amount of time.Furthermore, for cost reasons, any PLC was selected to exactly match the requirements of the environment within which it was intended to operate. That is why it cannot be assumed that a PLC will be able to support additional tasks such as communicating data through additional interfaces.