Siemens SIMATIC ET 200AL, System Manual

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Communications services
3.6 Secure Communication
Communication
Function Manual, 05/2021, A5E03735815-AJ
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3.6.3.5 Secure OUC with Modbus TCP
For secure Modbus TCP connection you need to create a data block with one of the system
data types TCON_IP_V4_SEC or TCON_QDN_SEC yourself, assign parameters and call it
directly at the MB_Server or MB_CLIENT instruction.
Requirements:
• S7-1500 CPU CPU firmware version V2.5 or higher
• The Modbus client (TLS client) can reach the Modbus server (TLS server) over IP
communication in the network.
• TLS client and TLS server have all the required certificates.
Example of setting up a secure Modbus TCP connection to a Modbus TCP server
The following section describes how you can set up a Secure Open User Communication over
Modbus TCP from a Modbus TCP client to a Modbus TCP server.
To set up a secure connection from a Modus TCP client (TLS client) to a Modbus TCP server
(TLS server) and set up the IPv4 address of the mail server, follow these steps:
1.
Create a global data block in the project tree.
2. Define a tag of the data type TCON_IP_V4 SEC in the global data block.
Figure 3-31 TCON_IP_V4_SEC
3. Set the connection parameters of the TCP connection in the "Start value" column. Enter the
IPv4 address of the mail server, for example, for the "MailServerAddress".