Automation and computerized control of processes in electric power plants were intensively started at the end of seventies and at the beginning of eighties during the introduction of microprocessor–based computer systems. The first generation of the information processing equipment has in most cases already become disused. From that time, visibility of controlled process has been increased by installing new and modern devices which enable better informing about all relevant events. The increased quantity of information by which processes can be described implies that new and more efficient techniques for information modeling should be developed. In this paper a device-based approach to process information modeling is proposed. Such modeling approach is more efficient than function-based approach we used before. The efficiency lies in the fact that device-based approach is in the very essence an object-oriented modeling approach. Therefore, device-based information models can be easily mapped to object-oriented models. Both function-based and device-based modeling approaches are described in the paper and differences between two modeling paradigms are emphasized. In the last Chapter of the paper analogy between device-based and object-oriented models is described. This analogy represents basis for the model mapping.