A property in the DA server is represented in the COM UA Wrapper as a Variable with TypeDefinition as PropertyType.
The properties for an item are retrieved using the QueryAvailableProperties call in the DA server.
Below are mappings of the property details to the OPC UA Property:
- The description of a property in the DA server is used as the BrowseName and the DisplayName of the Node in the COM UA Wrapper.
- The PropertyID and ItemID(if they exist for the property) in the DA server are used as a part of the NodeID for the node in the COM UA Wrapper.
- The DataType value in the DA server is used as value for the DataType Attribute of the Property in the COM UA Wrapper.
- If the property value in the DA server is an array, the ValueRank Attribute of the Property is set to OneOrMoreDimensions. Otherwise, it is set to Scalar.
- If the property has an ItemID in the DA server, then the AccessLevel attribute for the Node is set to ReadableOrWriteable. If not, it is set to Readable.
Table A.59 shows the mapping between the common OPC COM DA properties to the OPC UA Node attributes/properties.
Table A.59 – OPC COM DA to OPC UA Properties mapping
|
Property Name (PropertyID) of OPC COM DA |
OPC UA Information Model |
OPC UA DataType |
|
Access Rights (5) |
AccessLevel Attribute |
Int32 |
|
EU Units (100) |
EngineeringUnits Property |
String |
|
Item Description (101) |
Description Attribute |
String |
|
High EU (102) |
EURange Property |
Double |
|
Low EU (103) |
EURange Property |
Double |
|
High Instrument Range (104) |
InstrumentRange Property |
Double |
|
Low Instrument Range (105) |
InstrumentRange Property |
Double |
|
Close Label (106) |
TrueState Property |
String |
|
Open Label (107) |
FalseState Property |
String |
|
Other Properties (include Vendor specific Properties) |
PropertyType |
Based on the DataType of the Property |