8.4.7 Addressing of nodes
Nodes are the basic elements of OPC UA and are comparable with objects from object-oriented
programming. Nodes are used, for example, for user data (variables) or other metadata. Nodes
are used to model an OPC UA address space that also contains a type model with type denitions.
Node ID (NoteId)
Nodes in the OPC UA address space are unambiguously dened by a NodeId (Node Identier).
The NodeId consists of the identier ("identier"), identier type ("identierType") and a
namespace index ("namespaceIndex"). Namespaces are used to avoid name conicts.
The OPC Foundation has dened a number of nodes that provide information about the
respective OPC UA server. These nodes are located in the namespace of the OPC Foundation and
have the index 0. Furthermore, the OPC Foundation has dened data and variable types.
Namespace
Besides the OPC Foundation namespace described above, the namespace for accessing 3RW5
data is of interest: All variables or methods of a 3RW5 OPC UA server are located in the
namespace of the standard server interface "http://siemens.com/opcua/2020/controlproducts/
3rw55". By default, this namespace has the index 6. Another namespace with index 2 is "http://
siemens.com/opcua/2020/controlproducts/siriussimple".
Identier
The 3RW5 OPC UA server uses numeric identiers (IdentierType = NUMERIC) to identify the
nodes. These numeric identiers allow OPC UA clients to access the corresponding OPC UA
nodes (e.g. variables).
8.4.8 OPC UA variables
The 3RW5 OPC UA server supports the OPC UA specication "OPC 10000 100 ‑ Part 100: Device
Information Model". The information model contains the units for measured values and
parameters.
Faults and warnings
In addition to the individual variables for diagnostics, there is a variable for faults and warnings.
The description of the messages for faults and warnings are shown in separate tables.
Functions
8.4 OPC UA server
SIRIUS 3RW5 PROFINET communication modules
116 Equipment Manual, 05/2021, A5E35631297002A/RS-AD/004
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