OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
Communication
Function Manual, 11/2019, A5E03735815-AH
163
Display of the information of the OPC UA server
You have the following options:
● Online: You have all the available information displayed during the runtime of the
OPC UA server. To do so, navigate (browse) the address space of the server.
● Offline: You export an XML file that is based on the XML schemes of the OPC
Foundation.
Server methods created by the user (FB instance that can be called by an OPC UA
client) are not exported as of STEP 7 V15.1), see Providing methods on the OPC UA
server (Page 227).
● Offline with the Openness API: In your program, you use the API (Application
Programming Interface) of the TIA Portal to access the function for exporting all PLC tags
that can be read by OPC UA. This requires .NET Framework 4.0; see TIA Portal
Openness, Automating SIMATIC projects with scripts
(https://support.industry.siemens.com/cs/ww/en/view/109477163
).
● If you already know the syntax and the PLC program, you can access the OPC UA server
without first researching the information.
9.3.1.3 Runtime behavior of the OPC UA server
OPC UA server in operation
The OPC UA server of the S7-1500 CPU starts when you activate the server and download
the project to the CPU.
How to activate the OPC UA server is described here.
Behavior in the operating state STOP of the CPU
An activated OPC UA server remains in operation even if the CPU switches to "STOP". The
OPC UA server continues to respond to requests from OPC UA clients.
Server response in detail:
● If you request the values of PLC tags, you will get what were the latest values before the
CPU switched to or was set to "STOP".
● If you write values to the OPC UA server, the OPC UA server will accept those values.
However, the CPU will not process the values because the user program is not executed
in "STOP" mode.
An OPC UA client can nonetheless read the values written at STOP from the OPC UA
server of the CPU.
During restart, the CPU overwrites the values written at STOP with the start of the PLC
tags.
● If you call a server method, the error message 16#00AF_0000 (BadInvalidState) is output
because the server method (user program) is not running.
● Connections to the OPC UA server remain active during an operating mode transition
(STOP > RUN or RUN > STOP). Exception: OPC UA-relevant data is loaded, see next
section.
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