9 Definition of Ctrl Variable Attributes and Properties ToC Previous Next

9.4 Variable Properties ToC Previous Next

9.4.1 IEC Ctrl Variable Keywords ToC Previous Next

The IEC 61131-3 key word mapping to OPC UA Properties is formally defined in Table 34.

Table 34 – IEC 61131-3 Variable Key Word Property Definition

References NodeClass BrowseName DataType TypeDefinition ModellingRule
Instance of any Variable Type.          
HasProperty Variable RETAIN Boolean PropertyType Optional
HasProperty Variable NON_RETAIN Boolean PropertyType Optional
HasProperty Variable CONSTANT Boolean PropertyType Optional
HasProperty Variable AT String PropertyType Optional

The Property RETAIN indicates if the RETAIN key word is set for the Ctrl Variable. It provides an explicit declaration of “warm start” behaviour of the Ctrl Variable (and Ctrl Function Blocks and Ctrl Programs).

The Property NON_RETAIN indicates if the NON_RETAIN key word is set for the Ctrl Variable. It provides an explicit declaration of “warm start” behaviour of the Ctrl Variable (and Ctrl Function Blocks and Ctrl Programs).

The Property CONSTANT indicates if the CONSTANT key word is set for the Ctrl Variable. It provides a declaration of a fixed value for the Ctrl Variable. The Ctrl Variable cannot be modified.

The Property AT contains the location assignment to the Ctrl Variable as string if the AT key word is set for the Ctrl Variable.

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