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Siemens – OPC UA

For communication with Siemens S7 PLCs, DataTalk uses the OPC UA (Open Platform Communications Unified Architecture) protocol. This driver ensures high security, interoperability, and reliability — making it the recommended option for industrial data exchange.

OPC UA provides a secure, platform-independent communication layer that supports:

  • Authentication and encryption via certificates and secure channels (TLS-based).
  • Data integrity and confidentiality, ensuring messages cannot be tampered with or intercepted.
  • Standardized object models, enabling structured access to PLC variables.

Requirements

Before establishing the connection, ensure that:

  • Your Siemens S7 PLC supports OPC UA Server functionality (e.g., S7-1200, S7-1500 series with firmware supporting OPC UA)
  • The OPC UA Server feature is licensed and enabled on the PLC.
  • The PLC is accessible from the DataTalk server over the network (check IP connectivity, firewall, and VLAN settings).

Enabling OPC UA on Siemens S7 PLC

To enable OPC UA communication:

  1. Open TIA Portal and load your PLC project.
  2. In the Project Tree, navigate to:
    Devices > [Your PLC] > Properties > General > OPC UA.
  3. Enable the “Activate OPC UA Server” option.
  4. Configure:
    • Endpoint URL (e.g., opc.tcp://<PLC_IP_Address>:4840).
    • Security Policies — choose a secure mode such as Basic256Sha256 with Sign & Encrypt.
    • User Authentication — set credentials or use certificate-based authentication.
  5. Define Tags/Variables to be exposed through OPC UA:
    • Go to OPC UA > Access Rights and add the data blocks, inputs/outputs, or internal variables you want to publish.
  6. Download the configuration to the PLC and restart it if required.

Configuring DataTalk Connection

Once the OPC UA server is active:

  1. In the DataTalk configuration interface, create a new OPC UA connection.
  2. Enter the PLC’s endpoint URL (e.g., opc.tcp://192.168.0.10:4840).
  3. Import or trust the PLC’s server certificate if certificate validation is enabled.
  4. Provide authentication details:
    • Username/password, or
    • Client certificate/private key if certificate-based authentication is configured.
  5. Test the connection — DataTalk should list available OPC UA nodes (PLC variables).
  6. Map the desired nodes to internal DataTalk tags for use in dashboards, logic, or data logging.

Security Notes

Always use encrypted and signed communication modes (Sign & Encrypt).
Use unique certificates for each client connection.
Regularly update PLC and DataTalk software to maintain compatibility and security compliance.

Updated on November 12, 2025