Siemens SIMATIC ET 200AL, System Manual

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OPC UA communication
9.1 What you need to know about OPC UA
Communication
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9.1.6 What you need to know about OPC UA clients
Basics of OPC UA clients
OPC UA clients are programs that do the following:
•
Access the information from an OPC UA server (for example an S7-1500 CPU):
read/browse access, write access, subscriptions
• Execute methods through the OPC UA server
However, OPC US clients can only access data that is enabled for this purpose (see "Managing
write and read rights (Page 208)").
You need the endpoint of the server to establish a connection to an OPC UA server (see
"Endpoints of the OPC UA servers (Page 203)").
Reading out information from the OPC UA server
When a connection to an end point of the server exists, you can use the navigation function
of the client: You navigate starting from a defined starting point (from the "root" node)
through the address space of the server.
The following information is provided in the process:
•
Enabled PLC tags, data blocks and data block components
• Namespace index and identifiers of these PLC tags, data blocks and DB components
• Data types of the PLC tags and DB components
• Number of components in arrays (required for reading and writing arrays)
In addition, you receive information about the OPC UA server itself as well as information
about the S7-1500 based on the "OPC UA for Devices" standard of the OPC Foundation (for
example, serial number, firmware version).