The IEC 61131-3 key word mapping to OPC UA Propertiesis 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 PropertyRETAIN 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 Blocksand Ctrl Programs).

The PropertyNON_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 Blocksand Ctrl Programs).

The PropertyCONSTANT 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 Variablecannot be modified.

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