Accessing Opc Ua Server Data - Siemens SIMATIC ET 200AL System Manual

3. Select the "Attributes" area.
4. Select/clear the "DB accessible from OPC UA" checkbox as required.
Figure 9-8
Note
Effect on settings in the DB editor
If you hide a DB using the DB attribute described here, the settings for the components in
the DB editor are no longer relevant; individual components can no longer be accessed or
written.
9.3.1.3

Accessing OPC UA server data

High performance in line with application
OPC UA is designed for the transfer of a high volume of data within a short period of time.
You can increase the performance significantly if you do not access individual PLC tags, but
rather read and write arrays and structures as a whole.
It is fastest to access arrays. Therefore, you should combine the data for OPC UA clients
into arrays.
Recommendations for access to the OPC UA server by the OPC UA client
● For one-off or infrequent data access, use standard read/write access.
● For cyclic access to small amounts of data (up to ca. every 5 seconds), use subscriptions.
Optimize the settings for the smallest publishing interval and the smallest sampling
interval at the OPC UA server.
● If you access specific tags regularly (recurring access), you should use the functions
"RegisteredRead" and "RegisteredWrite".
Allow a greater communication load for the PLC by increasing the value for "Cycle load due
to communication". Make sure that your application still works properly with the changed
settings.
Communication
Function Manual, 12/2017, A5E03735815-AF
Hiding DBs or DB contents for OPC UA clients
OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
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