OPC UA PHP Client

Connect your PHP application directly to industrial PLCs, SCADA systems, sensors, historians, and IoT devices using the OPC UA standard — without any C/C++ extensions, HTTP gateways, or middleware in between.

This library implements the full OPC UA binary protocol stack in pure PHP: TCP transport, binary encoding/decoding, secure channel establishment with asymmetric and symmetric encryption, session management, and all the major OPC UA services. Just composer require and you're talking to PLCs from your Laravel app, your Symfony worker, or a plain PHP script.

What you can do with it:

• Read and write process variables from any OPC UA-compliant device — temperatures, pressures, motor speeds, setpoints, counters, anything the server exposes
• Browse the entire address space to discover what's available, build tree views, or auto-map variables
• Subscribe to data changes and events in real time — get notified when a sensor value changes or an alarm fires
• Call methods on the server — trigger operations, run diagnostics, execute commands on the PLC
• Query historical data — pull raw logs, aggregated trends (min, max, average), or interpolated values at specific timestamps
• Secure everything — 10 security policies: 6 RSA (plaintext to AES-256 with RSA-PSS) + 4 ECC (NIST P-256/P-384 and Brainpool P-256/P-384 with ECDSA/ECDH), plus anonymous, username/password, or X.509 certificate authentication ^*

All of this with zero external dependencies beyond ext-openssl, and full support for PHP 8.2 through 8.5.

Note: OPC UA relies on persistent sessions and long-lived connections. PHP's request/response model means connections are short-lived by default. For use cases like continuous monitoring or subscription polling, pair this with opcua-session-manager to persist sessions across requests — or use it in a long-running worker process.

The session manager is a separate package by design — it runs as a daemon process using ReactPHP and Unix sockets, which would break this library's zero-dependency, cross-platform philosophy if bundled here. See the Ecosystem section for details.

^* ECC note: The 4 ECC policies are implemented per OPC UA 1.05 spec but should be considered experimental. No commercial OPC UA server vendor has released devices with ECC endpoints yet — this is an ecosystem-wide gap. ECC support has been developed and tested exclusively against UA-.NETStandard (the OPC Foundation reference implementation). The implementation follows the 1.05.3 specification and is aligned with 1.05.4 regarding ReceiverCertificateThumbprint, HKDF salt encoding, and LegacySequenceNumbers = FALSE for ECC (sequence numbers start at 0 and wrap at UInt32.MaxValue; landed in v4.3.0). One ECC-specific change from 1.05.4 (per-message IV derivation) is not yet implemented — it is coupled to the future AEAD policy variants. See the Security documentation for details.

Quick Start

That's it. Three lines to build, connect, and read. No config files, no service containers, no XML.

Tip: All client methods accept NodeId strings like 'i=2259', 'ns=2;i=1001', or 'ns=2;s=MyNode' anywhere a NodeId is expected. Invalid strings throw InvalidNodeIdException.

See It in Action

Browse the address space

Read multiple values

Tip: You can also pass an array to readMulti([...]) -- the builder is just a fluent alternative.

Get server info

Resolve a path and read a value

Write to a PLC

Call a method on the server

Subscribe to data changes

Read historical data

Manage nodes at runtime

Supports all 8 node classes. See Node Management documentation for adding references, class-specific attributes, and error handling.

Connect with full security

Tip: Skip setClientCertificate() and a self-signed cert gets auto-generated in memory — perfect for quick tests or servers with auto-accept.

Decode custom structures with codecs

Each client gets its own isolated codec registry — no global state, no cross-contamination.

Test without a real server

MockClient implements OpcUaClientInterface with no TCP connection. Register handlers with onRead(), onWrite(), onBrowse(), onCall(), and onResolveNodeId(). Track calls with getCalls(), getCallsFor($method), callCount($method), and resetCalls(). Works with fluent builders (readMulti(), writeMulti(), etc.).

Add structured logging

Any PSR-3 logger works — Monolog, Laravel's logger, or your own. Without one, logging is silently disabled (NullLogger).

React to events (PSR-14)

47 granular events covering connection, session, subscription, data change, alarms, read/write, browse, cache, and retry. Zero overhead with the default NullEventDispatcher. See Events documentation for the full list.

Monitor alarms in real time

Explore from the terminal

Full security support, JSON output, debug logging, NodeSet2.xml code generation, and more. See php-opcua/opcua-cli for full documentation.

Trust server certificates

Trust on first use (TOFU):

Disable trust validation:

Or manage from the CLI with php-opcua/opcua-cli:

Auto-discover custom types

Extend the client with custom modules

The client ships with 8 built-in modules (ReadWrite, Browse, Subscription, History, NodeManagement, TranslateBrowsePath, ServerInfo, TypeDiscovery). Add your own or swap built-ins with addModule() and replaceModule(). See Modules for details.

Use pre-built OPC UA companion types

Instead of writing codecs by hand or relying on runtime discovery, install opcua-client-nodeset to get pre-generated PHP types for 51 OPC Foundation companion specifications — DI, Robotics, Machinery, MachineTool, ISA-95, CNC, MTConnect, and many more:

Each Registrar automatically loads its NodeSet dependencies. Use only: true to skip dependency loading if you manage them yourself.

Tip: You can also generate types from your own custom NodeSet2.xml files using opcua-cli generate:nodeset.

Why This Library?

• Zero runtime dependencies — only ext-openssl. Optional PSR-3 logging, PSR-16 caching, and PSR-14 events via any compatible implementation.
• PHP 8.2+ — runs on any modern PHP.
• Native binary protocol — speaks OPC UA directly over TCP. No HTTP gateway, no REST bridge, no sidecar.
• Full security stack — 10 policies: 6 RSA up to Aes256Sha256RsaPss + 4 ECC (NIST and Brainpool), 3 auth modes, auto-generated certs, persistent certificate trust store with TOFU.
• Industrial-ready — server certificate trust management, alarm event deduction, subscription recovery, auto-retry — built for certified industrial deployments.
• Batteries included — browse, read, write, call, subscriptions, events, history, path resolution, batching, retry, CLI tool.
• Cross-platform — tested on Linux, macOS, and Windows via CI. No FFI, no COM. Uses DIRECTORY_SEPARATOR and platform-aware defaults throughout.
• Thoroughly tested — 1700+ tests (1440+ unit, 290+ integration), 99%+ unit test code coverage across PHP 8.2, 8.3, 8.4, and 8.5 on all three platforms.
• Typed everywhere — all service responses return public readonly DTOs, not arrays.
• Session persistence — keep OPC UA connections alive across PHP requests via opcua-session-manager.
• Laravel-ready — drop-in via opcua-laravel-client.

Features

Documentation

Full documentation is available in docs/. Highlights:

Testing

1700+ tests with 99%+ code coverage. Unit tests cover encoding, crypto, protocol services, and error paths. Integration tests run against uanetstandard-test-suite — a Docker-based OPC UA environment built on the OPC Foundation's UA-.NETStandard reference implementation, with multiple security configs, custom types, and real-world scenarios.

CI runs on PHP 8.2, 8.3, 8.4, and 8.5 via GitHub Actions, in three phases: format check and PHPStan in parallel, then unit tests (Linux, macOS, Windows), then integration tests against the Docker test servers.

Alternatives & Comparison

PHP

Ecosystem

Community

Have questions, ideas, or want to share what you've built? Join the GitHub Discussions.

Connected a PLC, SCADA system, or OPC UA server? We're building a community-driven list of tested hardware and software. Share your experience in Tested Hardware & Software — even a one-liner like "Siemens S7-1500, works fine" helps other users know what to expect.

AI-Ready

This package ships with machine-readable documentation designed for AI coding assistants (Claude, Cursor, Copilot, ChatGPT, and others). Feed these files to your AI so it knows how to use the library correctly:

How to use: copy the files you need into your project's AI configuration directory. The files are located in vendor/php-opcua/opcua-client/ after composer install.

• Claude Code: reference per-session with --add-file vendor/php-opcua/opcua-client/llms-skills.md
• Cursor: copy into your project's rules directory — cp vendor/php-opcua/opcua-client/llms-skills.md .cursor/rules/opcua-client.md
• GitHub Copilot: copy or append the content into your project's .github/copilot-instructions.md file (create the file and directory if they don't exist). Copilot reads this file automatically for project-specific context
• Other tools: paste the content into your system prompt, project knowledge base, or context configuration

Roadmap

See ROADMAP.md for what's coming next.

Contributing

Contributions welcome — see CONTRIBUTING.md.

Changelog

See CHANGELOG.md.

License

MIT