The data extensions can be defined in the Data extensions configurator, in the configuration window setting the properties of each variable.
The data extensions are created (configuration and source part) in the Var item (variable) of the PmData (PmCommData, PmOpcClientData, PmTrend) object. Most types of the data extensions contain the reference to the target object, where the data extensions register and are given the desired functionality. For the target object, the data extensions act as dynamické items, that are created and registered into the objec at application launch, with automatic binding to the Var variable value, where the extensions are located.
The type of the target object is based on the type of the data extension. For example PmTrend for ExtTrend, PmCommData for ExtComm, PmOpcClientData for ExtOpcClient or PmAlarmEvent for ExtAlarmAnalog and ExtAlarmBinary.
Note! It is possible to find and display all data extensions in the PROMOTIC system, that contain reference to a specific target object. See List of data extensions.
References to Data extensions objects in the Var variable can also be done directly by extending the path of the Pm method using the #ext identifier. This can be used in Pm method or in PP binding in application and in panels. For example the pMe.Pm method ("/data/#vars/Temperature/#ext/al") returns the data binding with al identifier (ExtAlarmAnalog) in the "Temperature" variable (Var) in the "data" object (PmData).
The reference to Var object can also be done directly by extending the path of the Pm method using the #vars identifier. This identifier can be used in methods working with application object tree (e.g. for the Pm method), or for the PP binding in the application and in panels. For example the method Pm("/data/#vars/Temperature) returns the "Temperature" variable (Var) in the "data" object(PmData).
The contents of complete data extension (all configurators) can be saved as a single string.It is even possible to save all data extensions of one Var object as single string, where each data extension is separated by comma (','). This is used for displaying a list of data extensions in development environment, but above all it can be used for export/import of Var objects in CSV form.
The specific list and order of configurators is specified for each data extension.
|ExtAlarmAnalog||An extension for alarming the analog value|
|ExtAlarmBinary||An extension for alarming the Boolean value|
|ExtComm||An extension for connection to the PmCommData object|
|ExtDdeClient||An extension for connecting to the DDE server|
|ExtDdeServer||An extension for DDE server offering|
|ExtEvent||An extension for generating events|
|ExtOpcClient||An extension for connecting to the OPC DA communication.|
|ExtSubVar||Extending variable Var by subvariable|
|ExtTrend||An extension for connection to the PmTrend object|
|ExtWriteAction||An extension for invoking an event when writing a value|