Data extensions

The data extensions are PROMOTIC system components, extending the basic functionality of PmVar data items (variables).
Each data extension type is used for specific purpose (e.g. limit excess alarm, OPC server or connection to the PmaComm object, trends, etc.).
The data extensions can be defined in the "Data extensions" configurator, in the configuration window setting the properties of one variable.

The principle of data extensions:
The data extensions are created (configuration and source part) in the PmVar variable of the PmaData object (PmaCommGroup, PmaOpcDaClientGroup, PmaTrendGroup) object.
Most types of 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 object after the application is launched, with automatic binding to the PmVar variable value, where the data extensions are located.
The type of the target object is based on the type of data extension. For example
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.

Identifier #ext:
References to Data extensions objects in the PmVar variable can also be done directly by extending the path of the Pm method using the #ext identifier.
This can be used in the Pm method or in PP binding in the application and in panels.
For example the method pMe.Pm("/data/#vars/Temperature/#ext/al") returns the data extension with al identifier (ExtAlarmAnalog) in the "Temperature" variable (PmVar) in the data object (PmaData object).

Identifier #vars:
The reference to PmVar object can also be done directly by extending the path of the Pm method by means of the #vars identifier. This identifier can be used e.g. in the Pm method, or in the "PP - Data binding to Pma object property" data binding.
For example the method Pm("/data/#vars/Temperature) returns the "Temperature" variable (PmVar object) in the data object (PmaData object).

Format of saving the data extension in the form of a text string:
The content of complete of data extension (all configurators) can be saved in the form of single text string.
It is even possible to save content of all data extensions of one PmVar object in the form of single text string, where each data extensions 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 PmVar objects in CSV form.
The specific list and order of configurators is specified for each data extension.
List of data extension types:
AlarmAnalogData extension for alarm the numeric value
AlarmBinaryData extension for alarm the two-state value
ExtCommData extension for connection to the PmaCommGroup object
ExtDdeClientData extension for connection to the DDE server
ExtDdeServerData extension for DDE server offering
ExtEventData extension for generating events
ExtOpcDaData extension for connection to the OPC DA communication.
ExtSubVarData extension variable PmVar by subvariable
ExtTrendData extension for connection to the PmaTrendGroup object
ExtWriteActionData extension for testing and modification of written value
See also:
- PmVar (object)
- PmVar.Extension (method)
- PmaData (object)

Pm8.03.11: Fixed bug: When data extensions were modified in the development environment, the changes did not save (bug since Pm8.3.10 version).
Pm8.03.00: Data extension is now an object with scripting interface.
- The PmVar.Extension method can access this object. The data extension was available for variables of the PmaData object, but now it can also be used with PmaCommGroup, PmaOpcDaClientGroup and PmaTrendGroup object variables. In these objects there is always just one extension "to itself", i.e. the ExtComm, ExtOpcDa and ExtTrend data extension.
- The data extension object can also be addressed in the object path by #ext identifier.
PROMOTIC 9.0.27 SCADA system documentation MICROSYS, spol. s r.o.

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