Method for operating a forming device for forming plastic preforms into plastic containers , wherein in a working mode of the apparatus , the plastic preforms are transported by means of a plurality of forming stations along a predefined transport path, and by applying a flowable medium are expanded into plastic containers , wherein to expand the plastic preforms , blow-moulding devices are used, inside which the plastic preforms are expanded into plastic containers , wherein in a change mode, at least one of the blow-moulding devices is removed from the apparatus and/or one of the blow-moulding devices is arranged on a blow-mould carrier of the apparatus , wherein to change the blow-moulding devices , a change device is used which has a gripper device for gripping the blow-moulding device , in a working mode, the forming device is operated in a first protected area (S1) which is not accessible to a machine operator during production, and the change device is arranged at least partially in a second protected area (S2) which is accessible for the machine operator for at least part of the time in working mode, wherein a connection can be created between the first protected area (S1) and the second protected area (S2) in such a way that the first protected area (S1) and the second protected area (S2) are connected together via an interface, wherein this interface also allows interruption of the connection and wherein the change device is itself placed locally outside a protected area of the machine or the forming device and the protected area is walls which surround the machine and which prevent access to the machine area during the working mode or light barrier systems are provided, which prevent access to the forming device during operation, wherein during a working mode of the plant, a change process is prepared in the second protected area, wherein preparation means the provision of blow-moulding units to be inserted or a detection of blow-moulding devices, characterised in that before or during the change process, blow-moulding parts are identified by means of an identification device, wherein data characteristic of their position within a magazine are assigned to the blow-moulding parts identified or to be identified. that the first protected area (S1) and the second protected area (S2) are connected together via an interface, wherein this interface also allows interruption of the connection and wherein the change device is itself placed locally outside a protected area of the machine or the forming device and the protected area is walls which surround the machine and which prevent access to the machine area during the working mode or light barrier systems are provided, which prevent access to the forming device during operation, wherein during a working mode of the plant, a change process is prepared in the second protected area, wherein preparation means the provision of blow-moulding units to be inserted or a detection of blow-moulding devices, characterised in that before or during the change process, blow-moulding parts are identified by means of an identification device, wherein data characteristic of their position within a magazine are assigned to the blow-moulding parts identified or to be identified. <EOS>