# OPC UA

Protocols · `OPC-UA` · verification: source checked

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.

## Specification

| Property | Value |
|---|---|
| Transports | tcp |
| Architecture | client server |
| Encoding | binary |

### Default ports

| Port | Transport | Secure | Purpose |
|---|---|---|---|
| 4840 | tcp | false | OPC UA Connection Protocol |
| 4843 | tcp | true | OPC UA TCP Protocol over TLS/SSL |

## Connected

- Related: [Ethernet-APL](https://machineschema.com/protocol/ethernet-apl.md), [ISA-100.11a-2011](https://machineschema.com/protocol/isa100-11a.md), [Module Type Package (MTP)](https://machineschema.com/protocol/mtp.md), [OPC Data Access (OPC DA)](https://machineschema.com/protocol/opc-classic-da.md), [OPC Foundation OPC UA FX](https://machineschema.com/protocol/opc-ua-fx.md), [OPC Foundation OPC UA for Robotics](https://machineschema.com/protocol/opc-ua-robotics.md), [OPC UA Safety](https://machineschema.com/protocol/opc-ua-safety.md), [PI PROFINET over TSN](https://machineschema.com/protocol/profinet-over-tsn.md), [umati OPC UA for Machine Tools](https://machineschema.com/protocol/umati.md)
- Supported by: [Beckhoff CX8091](https://machineschema.com/hardware/beckhoff-cx8091.md), [Beckhoff CX8110](https://machineschema.com/hardware/beckhoff-cx8110.md), [Beckhoff CX8180](https://machineschema.com/hardware/beckhoff-cx8180.md), [Beckhoff CX8190](https://machineschema.com/hardware/beckhoff-cx8190.md), [Beckhoff CX8191](https://machineschema.com/hardware/beckhoff-cx8191.md), [Brother H550Xd1](https://machineschema.com/hardware/brother-h550xd1.md), [Brother HU550Xd1](https://machineschema.com/hardware/brother-hu550xd1.md), [Brother HU550Xd1-5AX](https://machineschema.com/hardware/brother-hu550xd1-5ax.md), [Brother M200Xd1](https://machineschema.com/hardware/brother-m200xd1.md), [Brother M200Xd1-5AX](https://machineschema.com/hardware/brother-m200xd1-5ax.md), [Brother M300Xd1](https://machineschema.com/hardware/brother-m300xd1.md), [Brother M300Xd1-5AX](https://machineschema.com/hardware/brother-m300xd1-5ax.md), [Brother M300Xd2-5AX](https://machineschema.com/hardware/brother-m300xd2-5ax.md), [Brother M300Xd2-5AX/64T](https://machineschema.com/hardware/brother-m300xd2-5ax-64t.md), [Brother M300Xd2-64T](https://machineschema.com/hardware/brother-m300xd2-64t.md), [Brother R450Xd2](https://machineschema.com/hardware/brother-r450xd2.md), [Brother R650Xd2](https://machineschema.com/hardware/brother-r650xd2.md), [Brother R650Xd2 40tools](https://machineschema.com/hardware/brother-r650xd2-40tools.md), [Brother S500Xd1](https://machineschema.com/hardware/brother-s500xd1.md), [Brother S500Xd2-5AX](https://machineschema.com/hardware/brother-s500xd2-5ax.md), [Brother S700Xd1](https://machineschema.com/hardware/brother-s700xd1.md), [Brother S700Xd2](https://machineschema.com/hardware/brother-s700xd2.md), [Brother S700Xd2-100T](https://machineschema.com/hardware/brother-s700xd2-100t.md), [Brother S700Xd2-5AX](https://machineschema.com/hardware/brother-s700xd2-5ax.md), [Brother S700Xd2-5AX/100T](https://machineschema.com/hardware/brother-s700xd2-5ax-100t.md), [Brother U500Xd1](https://machineschema.com/hardware/brother-u500xd1.md), [Brother W1000Xd2](https://machineschema.com/hardware/brother-w1000xd2.md), [Brother W1000Xd2-5AX](https://machineschema.com/hardware/brother-w1000xd2-5ax.md), [Comau N-220-2.7](https://machineschema.com/hardware/comau-n-220-2-7.md), [DMG MORI LASERTEC 30 SLM 3rd Generation](https://machineschema.com/hardware/dmg-mori-lasertec-30-slm-3rd-generation.md), [FANUC R-30iB Plus](https://machineschema.com/controller/fanuc-r-30ib-plus.md), [FANUC R-50iA](https://machineschema.com/controller/fanuc-r-50ia.md), [Franka Robotics Franka Research 3](https://machineschema.com/hardware/franka-robotics-franka-research-3.md)

## Safety

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

## 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.

## Sources

1. [IANA Service Name and Transport Protocol Port Number Registry (opcua-tcp, opcua-tls)](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml?search=opcua) (accessed 2026-10-25)
2. [OPC UA Online Reference](https://reference.opcfoundation.org/) (accessed 2026-10-25)

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Source page: https://machineschema.com/protocol/opc-ua  
JSON: https://machineschema.com/protocol/opc-ua.json  
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite Machine Schema and the original sources.