About OPC Unified Architecture
R2026bThe OPC Unified Architecture (OPC UA) standard combines all the capabilities of OPC Data Access and OPC Historical Data Access standards (together, referred to as "OPC Classic") and adds various additional capabilities into a single, extensible standard. OPC UA servers provide a single namespace that organizes the data available on the server into a hierarchical view of nodes (also called items in OPC Classic terminology). Nodes on OPC UA servers can be object nodes, variable nodes, or method nodes. Object nodes help to organize other nodes. Variable nodes store values that represent some process value on the server. These nodes can also contain other variable nodes. Method nodes represent function calls for object specific processes. Nodes are arranged in several representations; for Industrial Communication Toolbox™, the nodes appear as a hierarchical tree, with nodes containing subnodes called children.
OPC UA servers are required to publish a node in their namespace named "Server". The
Server node provides information about the OPC UA server, including the capabilities of
the server, specific limitations of the server, and other information related to the
server. Industrial Communication Toolbox provides selected information from the Server node as properties of the
client you create to connect to that server. For information on client properties, see
opc.ua.Client.
OPC UA servers may or may not historize Variable nodes. For historizing nodes, OPC UA
servers store prior values of the node, and can provide that history to OPC UA Clients
as raw data (data points at the times that the server stored the Value), or as data at
requested times (the server interpolates the raw data using either sample-and-hold or
linear interpolation), or as processed data, using a predefined aggregate function that
the user requests. Each OPC UA server describes which Aggregate Functions are supported
by that server. "OPC UA Aggregate Functions" describes the standard aggregate functions
defined in the OPC UA specification. Servers might implement custom aggregate functions;
consult the specific OPC UA server reference for information on how those functions
work. Industrial Communication Toolbox provides a client interface to the OPC UA servers that allows you to
browse the server namespace to find nodes of interest. The toolbox also supports the
opc.tcp binary protocol and anonymous, unsecured connections. You
can also use the client to define the security configuration for the connection, and
provide user credentials to the server. The toolbox supports the
opc.tcp binary protocol only; HTTP and HTTPS connections are not
supported. For some of the tasks you can perform with Industrial Communication Toolbox, see the related examples.
