The interaction approach introduced in this paper is aiming at coupling a full-fledged discrete event simulator and an operational ERP system in a fully integrated manner. Here, the simulator is representing the complete operative environment of the ERP system, substituting its daily business input. For this, the company-specific utilisation of the ERP system has to be modelled in the simulator. In order to execute its model and process concrete ERP functionality, the simulator is accessing the ERP system via software interfaces, using it like a large subject-specific software library. Thus, the simulator is effectively carrying out a complete remote control of the ERP system, in the sense of software automation. Amongst others, the simulator is inducing arrival and booking events in the ERP system, is continuously triggering internal ERP system processes and is processing the results of revised ERP planning by arranging future events in the ERP system. Altogether, the simulator and the ERP system are interacting mutually with each other in a cyclic process. In this paper, we introduce the core idea of the interaction approach and delineate its potentials. We discuss arising challenges in practical application and describe the current state of implementation.