End Points Of The Opc Ua Server - Siemens SIMATIC ET 200AL System Manual

Address space
The nodes are linked over references, for example, the reference "HasComponent, which
represents a hierarchical relationship between a node and its subordinate nodes. With their
references, the nodes form a network that can, for example, take the form of a tree.
A network of nodes is also called an address space. Starting from the root, all nodes can be
reached in the address space.
9.3.1.2

End points of the OPC UA server

The end points of the OPC UA server define the security level for a connection. Depending on
the purpose of use or desired security level, you have to carry out the corresponding settings
for the connection at the end point.
Different security settings
Before establishing a secure connection, OPC UA clients ask the server with which security
settings connections are possible. The server returns a list with all the security settings
(endpoints) that the server offers.
Structure of end points
End points consist of the following components:
• Identifier for OPC: "opc.tcp"
• IP address: 192.168.178.151 (in the example)
• Port number for OPC UA: 4840 (standard port)
The port number can be configured.
• Security setting for messages (Message Security Mode): None, Sign, SignAndEncrypt.
• Encryption and hash procedures (Security Policy): None, Basic128Rsa15, Basic256,
Basic256Sha256 (in the example).
The following figure shows the "UA Sample Client" of the OPC Foundation.
The client has established a secure connection to the OPC UA server of an S7-1500 CPU to the
end point "opc.tcp://192.168.178.151:4840 - [SignAndEncrypt: Basic256Sha256:Binary]". The
security settings "SignAndEncrypt:Basic256Sha256" are contained in the end point.
Note
Select an endpoint with as strict as possible a security policy
Select an application-appropriate security policy for the end point and disable the less strict
security policy at the OPC UA server.
A Sha256 certificate is required for the most secure end points (Basic256Sha256) of the S7-
1500 CPU OPC UA server.
Communication
Function Manual, 05/2021, A5E03735815-AJ
OPC UA communication
9.3 Using the S7-1500 as an OPC UA server
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