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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Function Manual, 05/2021, A5E03735815-AJ
• Usage
The default is "OPC UA client & server". Keep this default for the OPC UA server. The
"Create a new certificate" dialog can be called from several points in STEP 7. If, for
example, you call this dialog for the Web server of the CPU, "Web server" is entered under
"Usage". The following entries are available in the Usage drop-down list:
– "OPC UA client"
– "OPC UA client & server"
– "OPC UA server"
– "TLS"
– "Web server"
• Subject Alternative Name (SAN)
The following is entered in the example above: "URI:urn:SIMATIC.S7-1500.OPC-
UAServer:PLC1,IP:192.168.178.151,IP:192.168.1.1". This URI must be correctly entered
because it is checked against the communicated application description.
The following entry would also be valid: "IP: 192.168.178.151, IP: 192.168.1.1". The
important thing here is that the IP addresses via which the OPC UA server of the CPU can
be accessed are entered here.
See "Access to the OPC UA server (Page 220)".
This allows OPC UA clients to verify whether a connection to the OPC UA server of the
S7-1500 is really to be established or whether in fact an attacker is trying to send
manipulated values from another PC to the OPC UA client.