Use the symbol configuration to prepare symbols with specific access rights for project variables. You can use these symbols to access the variables externally.

When generating code, CODESYS also generates a symbol file (*.xml) which includes the description of the symbols.

The symbol file is stored in the project directory. The name of the symbol file is composed as follows: ‎<project name>.<device name>.<application name>.xml‎

The variables that you export as symbols can be bundled in the ⮫ symbol configuration editor or defined in the variables declaration using the ‎{attribute 'symbol'}‎ pragma. Another option is using the element in the SFC editor, where you can define the implicitly generated element variables that should be exported to the symbol configuration. For more information, see: ⮫ SFC Element Properties

The name of the symbol is generated in the symbol configuration in the following syntax: ‎<application name>.<POU name>.<variable name>‎. When accessing the variable, you always have to provide the complete symbol name in this syntax.

The symbol file is downloaded together with the application to the PLC. Depending on the device description, this file can be generated as an additional (child) application. This application is then listed on the ⮫ Applications tab of the device editor.

Syntax: ‎<application name>._Symbols‎

The symbol application is regarded as a "normal" application with respect to the maximum number of applications on the PLC.

If the controller has a user management, then you can assign different access rights to a symbol to the individual user groups (clients). To do this, place the same symbol in different symbol sets and allow the individual user groups (clients) either to access a symbol set or not. An on-site operator or an operating data record, for example, receives more information and access to the same symbols as remote maintenance.