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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9.3.2.6
MinimumSamplingInterval attribute
MinimumSamplingInterval attribute of tags
In addition to "Value", "DataType" and "AccessLevel", you can also set the
"MinimumSamplingInterval" attribute for a tag in the XML file that represents the server
address space.
The attribute specifies how fast the server can sample the tag value.
The OPC UA server of the S7-1500 CPU handles the values for MinimumSamplingInterval as
follows:
•
Negative values and values greater than 4294967 are set to -1; this means: The minimum
sampling rate is indeterminate. The server does not specify how fast the tag value can be
sampled.
•
Decimal numbers are rounded to three decimal places.
9.3.2.7
Export OPC UA XML file
Generating an OPC UA export file
The OPC Foundation has specified a standard XML-based format for describing information
models. It allows the information model of an OPC UA server to be provided to a client in
advance, or information models can be downloaded to an OPC UA server. A file in this format
is called a nodeset file because it describes an information model as a set of nodes.
With STEP 7 (TIA Portal) you can easily export the standard SIMATIC information model of the
S7-1500 CPU as a server to an OPC UA XML file (node set file); including all PLC variables and
methods you have enabled for OPC UA.
You use the OPC UA XML file for the offline configuration of an OPC UA client; it is structured
according to the OPC UA specification and acts as a standard SIMATIC server interface.
To create and export the OPC UA XML file, follow these steps:
1.
Select the CPU. Click on the CPU symbol (for example in the network view).
2.
Click "General > OPC UA > Server > Export" in the properties of the CPU.
3.
Click "Export OPC UA XML file".
4.
Select the directory in which you want to save the export file.
5.
Select a new name for the file or keep the name that is already entered.
6.
Click "Save".
Note
As of STEP 7 (TIA Portal) V15.1, server methods are contained in the OPC UA export file (node
set) together with their input and output parameters.
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