Rules For The Access To Structures - Siemens SIMATIC S7-1500 Function Manual

OPC UA communication
9.4 Using the S7-1500 CPU as an OPC UA client
When you change the editing language, the multilingual text in the imported interface will
also change according to the rules explained above.
You can then apply the nodes in the corresponding lists (read list, write list, method list) with
drag and drop.
You cannot change the language in the lists (read list, write list, method list).
Applying the displayed description texts as comment in PLC data types
When you compile the program, STEP 7 automatically creates PLC data types (UDTs) for
each read list, for each write list and for inputs or outputs of each method. These UDTs each
have one element for each node.
The UDTs apply the description text as comment according to the rules stated above.
STEP 7 creates the comment in only one language, just like the texts in the OPC UA server
interface can only be displayed in one language.
9.4.8

Rules for the access to structures

The rules for the access to structures are explained below. Note these rules when reading
and writing values of complete structures provided by an OPC UA server.
How the client of the S7-1500 CPU accesses structures
The OPC UA client of the S7-1500 CPU uses neither TypeDictionaries nor
DataTypeDefinition attributes, which a server offers for the resolution of these structures.
These options of the OPC UA client for checking structural elements in runtime are limited in
the client.
Rules for the access to structures
If you use the client interfaces to configure the read and write lists (connection
parameterization) and assign the PLC data types to the imported or online determined
address model of the server, the read and write accesses to structures operate trouble-free
in runtime.
The configuration by means of client interface automatically ensures that the sequence and
the data type of the structural elements are coordinated on client and server side.
Recommendation: Update an S7-1500 CPU (as server) to the current firmware version (e.g.
V2.0 > V2.5.2 or higher).
In runtime the OPC UA client only checks the total length of the transmitted value; more
detailed checks are not possible.
Mapping rules apply to the assignment of OPC UA structures to PLC tags or DB tags (see
Mapping of data types (Page 142)). Non-executed data type (such as OPC UA byte strings)
are not supported.
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Function Manual, 11/2019, A5E03735815-AH
Communication