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.