Identifier for OPC items
To identify OPC Items the TdOPCDAClient works with unique ItemIds. The ItemId is a string.
Here an example how to add an ItemId to a OPC group:
In OPC UA, every entity in the address space is a unique node.
Each node has a NodeId object, which is has 3 properties:
Property |
|
NamespaceIndex |
The namespace index as a number. Default is 0. |
IdentifierType |
The data type of the identifier. Default is string |
Identifier |
The identifier for a node. |
Following Identifier types are supported:
IdentifierType |
character |
number |
i |
string |
s |
globally unique identifier (GUID) |
g |
opaque value (ByteString) |
b |
To convert a NodeId object to a string based ItemId you have to use following format:
Examples:
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