The symbol configuration is used to create symbols, provided with specific access rights. They allow project variables to be accessed externally, for example by Vijeo-Designer, EcoStruxure Operator Terminal Expert, or OPC server. The description of the symbols will be available in an XML file (symbol file) in the project directory. It will be downloaded to the controller together with the application.
The symbols defined for an application are exported to an XML file in the project directory (symbol file) when the application is downloaded to the controller. This file is named according to the following syntax:
<project name>.<device name>.<application name>.xml
Example: proj_xy.PLC1.application.xml
Symbols for input addresses and variables that are mapped to input channels allow read-only access. Write access is only allowed for testing purposes in simulation mode.
Further on the symbol information is downloaded to the controller with the application. Depending on the device description, it will be included in the application or a separate child application will be generated. This will also be listed with the name <application name>._symbols in the Applications view of the device editor.
If the symbol configuration has been modified in online mode, you can reload it to the controller by clicking the button Download in the editor window.
For example, concerning the maximum number of applications on a controller, the symbol application has to be handled as a normal application.
If your controller has user management active, you can grant individual access rights to a symbol for different user groups (clients). To achieve this, place the same symbol in different symbol sets and allow or deny access to this symbol set for the individual user groups (clients).