Siemens SIMATIC ET 200AL - Accessing OPC UA Server Data

OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
Communication
Function Manual, 12/2017, A5E03735815-AF
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3. Select the "Attributes" area.
4. Select/clear the "DB accessible from OPC UA" checkbox as required.
Figure 9-8 Hiding DBs or DB contents for OPC UA clients
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 com
ponents 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.