Control Device Having an Integrated Machine Model

A production machine can be controlled by a control device in accordance with a control program which is stored in the control device. The production machine has at least two elements having interfaces, which are connected to one another at the interfaces. The control device stores element descriptions of possible elements, which respectively comprise at least one list of the existing interfaces, such that the control device can determine which elements can be connected to one another. The control device also stores a desired expansion description which at least comprises which elements the production machine has and which interfaces are said to connect the elements to one another. The control device has an operator interface which an operator of the production machine can use to request the desired expansion description which can be output to the operator on the basis of the request and can be changed by the operator.