OPC UA
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OPC UA (Open Platform Communications Unified Architecture) is a platform-independent, service-oriented communication protocol for secure and standardized data exchange between industrial systems. It is widely adopted in automation, manufacturing, and process control to enable seamless communication between PLCs, SCADA systems, and IT infrastructure.
Unlike Modbus or EtherNet/IP, OPC UA does not communicate directly with a PLC. A dedicated OPC UA server (running on the PLC, a gateway, or a PC) acts as an intermediary — all data access is mediated by the server’s published address space.
Supported data types
| Category | Examples |
|---|---|
| Numeric | Int, Float, Byte, Short, Double, … |
| Text | String, DateTime, Date, … |
| Boolean | Bool |
| Collections | Array, List, Set, … |
| References | Reference |
| Objects | Object |
Security
| Feature | Description |
|---|---|
| Basic Security | Username/password authentication |
| X.509 certificates | Certificate-based client authentication |
| Transport Layer Security (TLS) | Encrypts all communication between client and server |
| Message-based Security | Signs and/or encrypts individual messages |
| Anonymous Auth. | Connects without credentials — for unsecured lab environments only |
Security recommendations
Always use Sign & Encrypt mode in production. Use unique certificates per client connection. Keep PLC and DataTalk software updated for security compliance.
Endpoint URL format
opc.tcp://192.168.1.100:4840
opc.tcp://localhost:4840
opc.https://192.168.1.100:443Connection parameters
| Parameter | Description |
|---|---|
| Endpoint URL | OPC UA server address, e.g. opc.tcp://192.168.1.10:4840 |
| Security mode | None / Sign / SignAndEncrypt |
| Authentication | Anonymous, username/password, or certificate |
| Certificate | Client certificate for certificate-based sessions |