OPC UA

OPC Unified Architecture is a platform-independent standard for exchanging industrial data. Servers expose an address space of typed nodes that clients browse, read, write and subscribe to. Security is built into the protocol through signed and encrypted sessions.

Source checked7/7 values · 2026-10-25

Specification

2 sources

Transports	tcp
Architecture	client server
Encoding	binary

Default ports

IANA assignments

4840TCPOPC UA Connection Protocol

4843TCPOPC UA TCP Protocol over TLS/SSL

Study notes

Everything in an OPC UA server is a node with a NodeId. Nodes are linked by references, which lets a client browse a machine like a file tree.
Subscriptions let a client receive value changes without polling.

Safety

Security mode None disables signing and encryption. Use Sign or SignAndEncrypt outside a lab.