The data extensions can be defined only in the PmData object. The created application must contain at least one object that provides the requested functionality, for example the PmTrend obect for trending or the PmCommData object for connection to communication driver, etc.
The data extensions can significantly simplify the design of the application and allow to concentrate the logic of processing the desired valuo on a single spot – into the PmData object. Based on this concept, the PmData object becomes the central object of data storage and processing in current application.
The concept of data extensions is frequently used in order to simplify the process of data reading, trending, alarming, etc. The following chapters of this coursebook contain detailed instructions focusing on the usage of data extensions in your applications.