Additional important functionality of the PROMOTIC system that helps to simplify the design and development of an application is represented by the data extensions
. Data extensions allow to integrate new functionality to particular variables
in the PmaData
object. In another words, for each variable in the PmaData
object you can define what operation to do with it. The variable can be read from the communication driver
or from the OPC server
, written to the trend system
, evaluated for alarm
, etc. Multiple data extensions
can be defined for each variable.
The data extensions
can be defined only in the PmaData
object. The created application must contain at least one object that provides the requested functionality, for example the PmaTrendGroup
object for trending or the PmaCommGroup
object for connection to communication driver
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 PmaData
object. Based on this concept, the PmaData
object becomes the central object of data storage and processing in the application.
The concept of data extensions is frequently used in order to simplify the process of data reading, trending
, etc. The following chapters of this coursebook contain detailed instructions focusing on the usage of data extensions in your applications.