Siemens SIMATIC ET 200AL System Manual page 1327

OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
Download to the CPU may affect OPC UA server
If you load a CPU with running OPC UA server, you may need to stop and restart the server
depending on the loaded objects. In this case, active connections are interrupted and must be
re-established once the server restarts.
The duration of the restart depends mainly on the following parameters:
• The scope of the data structure
• The number of variables visible in the OPC UA address space
• The setting for downward compatible data type definition according to OPC UA
specification to V1.03 (TypeDictionary enabled)
• Settings for the communication load and minimum cycle time, you can find additional
information here (Page 354)
With CPU FW versions older than V2.8, the OPC UA server was stopped at each download to
the CPU and then restarted.
As of FW version V2.8, the behavior of the OPC UA server has been optimized as follows:
• When objects are downloaded in STOP operating state of the CPU, the OPC UA server still
always stops and then restarts. STEP 7 does not show a warning in this case.
• When objects are downloaded in RUN operating state of the CPU, the OPC UA server only
stops if the downloaded objects are, or could be, OPC UA-relevant. The OPC UA server
restarts after re-initialization due to the modified OPC UA data.
Before OPC-UA-relevant objects are loaded into the CPU and stop the OPC UA server, STEP
7 displays a warning in the preview dialog for loading. You can then decide whether a
server restart is compatible for the running process or whether you want to cancel the
download. These warnings are only displayed when the OPC UA server is running. If the
OPC UA server is not enabled, modified OPC UA data have no influence on the download
process.
Examples
• You only want to add another code module to the program.
Neither data blocks nor inputs, outputs, flags, times or counters are affected.
Reaction during loading: A running OPC UA server is not interrupted.
• You want to load a new data module and you have flagged the data module as non-OPC-
UA-relevant:
Reaction during loading: A running OPC UA server is not interrupted.
• You want to overwrite a data module.
Reaction during loading: A warning appears that the server will be restarted.
Background: STEP 7 cannot determine whether the changes refer to OPC-UA-relevant data
or not.
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Function Manual, 05/2021, A5E03735815-AJ
Communication