libplctag を Homebrew, Nix でインストール

プロジェクトリンク

• ホームページ

コマンドとエイリアス

• modbus_server
• tag_rw2

プロジェクトの歴史

The upstream history page says the project began because the maintainers wanted the practical PLC access they needed without the cost, size, Windows/OLE dependency, and licensing constraints they associated with OPC implementations. They evaluated older PCCC libraries and TuxEIP, found licensing, portability, maintainability, and API-shape problems, then wrote their own library without copying TuxEIP code.

The README states that libplctag has been in production use since early 2012. Over time the project kept a C core, a deliberately small API, and examples/wrappers for higher-level languages.

採用の歴史

Upstream describes production use across radio telescopes, manufacturing, fitness equipment, food handling, and other industrial settings. That adoption pattern is narrower than a general developer library but unusually practical: it is used where software talks to physical PLC-controlled systems.

The project also grew a wrapper ecosystem, including .NET, Go, Java, Julia, C++, Python, and Pascal bindings or examples. That made the C library a common native core for language-specific automation clients.

使われ方

Developers use libplctag to read and write PLC tag values, list tags, handle callbacks, and build small command-line or service tools around Allen-Bradley/Rockwell and Modbus TCP devices.

Package users see helper executables such as `tag_rw2` and examples, but the package's main role is as a native library dependency for industrial-control applications.

パッケージ好きにとっての重要性

libplctag is notable because it packages industrial automation access as a normal open-source C dependency. That is unusual territory for package managers: real machinery, proprietary protocol history, cross-platform binaries, and wrappers all meet in one modest library.

The dual MPL-2.0/LGPL-2.0-or-later licensing also matters for integrators who need something less restrictive than GPL-only PLC code.

タイムライン

• 2012: The README states that libplctag has been in production use since early 2012.
• 2022: The API wiki history records updates for 2.4.0 and 2.5.0 API changes.
• 2026: The README lists tier-one platform testing across Linux, macOS, and Windows combinations.

Related projects

• TuxEIP/TuxPLC is the abandoned earlier EtherNet/IP-related codebase discussed in libplctag's origin story.
• libplctag.NET, goplctag, libplctag4j, and PLCTag.jl are related wrappers that expose the C core to other language ecosystems.
• OPC is the larger industrial-automation integration family that libplctag's maintainers explicitly wanted to avoid for their narrower use case.

ソース

• https://github.com/libplctag/libplctag
• https://github.com/libplctag/libplctag/wiki/API
• https://libplctag.github.io/
• https://raw.githubusercontent.com/libplctag/libplctag/master/README.md
• https://raw.githubusercontent.com/wiki/libplctag/libplctag/History.md