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
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4. Ensure that the "Data block accessible via OPC UA" column is selected.
5. Select only the data blocks that are to be accessible via OPC UA.
Figure 9-12 Overview of the program blocks
9.3.2.3 Coordinating write and read rights for CPU tags
Definition of write and read rights in the information model (OPC UA XML)
In the OPC UA information model, the attribute "AccessLevel" regulates access to tags.
AccessLevel is defined bit by bit:
Bit 0 = CurrentRead and Bit 1 = CurrentWrite. The meaning of the bit combinations is as
follows:
•
AccessLevel = 0: no access
• AccessLevel = 1: read only
• AccessLevel = 2: write only
• AccessLevel = 3: read+write
Example of the assignment of write and read rights (read+write)
Definition of write and read rights in STEP 7
When you define tags, you specify the access rights using the properties "Accessible from
HMI/OPC UA" and "Writable from HMI/OPC UA".
Example of the assignment of write and read rights
Figure 9-13 Example of the assignment of write and read rights