Siemens SIMATIC ET 200AL, System Manual

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OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
Communication
Function Manual, 05/2021, A5E03735815-AJ
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How frequently does the server send notifications?
When a Subscription is set up, the OPC UA client specifies the intervals at which it wants to be
sent the new values in the event of changes. To limit the communication load through
OPC UA, set a minimum interval for the messages. For this purpose, use the parameters for
the minimum publishing interval and the minimum sampling interval.
Figure 9-17 Principle of a subscription
Minimum publishing interval
With "Minimum publishing interval", you set the time intervals at which the server sends a
message to the client with the new values in the event of changes.
250 ms is used as the "Minimum sampling interval" in the figure below. The value 200 ms is
entered as the "Minimum publishing interval".
Figure 9-18 Subscription settings
In the example, following a value change the OPC UA server will send a new message every
200 ms if the OPC UA client requests an update.
If the OPC UA client requests an update every 1000 ms, the OPC UA server will only send a
message with the new values once every 1000 ms (one second).
If the OPC UA client requests an update every 100 ms, the server will still only send a
message every 200 ms (minimum publishing interval).