# Install libplctag with Homebrew, Nix Portable and simple API for accessing AB PLC data over Ethernet. Version 2.7.0 via Homebrew; verified from local package data. Also installable with nix: nix profile install nixpkgs#libplctag. ## Install ```sh sudo av install brew:libplctag ``` Additional install commands: ### macOS - Homebrew (100%): ```sh brew install libplctag ``` Evidence: local Homebrew formula metadata ### Linux - Nix (92%): ```sh nix profile install nixpkgs#libplctag ``` Evidence: nixpkgs package indexes: pkgs/by-name/li/libplctag/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1 ## Package facts - **Package key:** brew:libplctag - **Package manager:** Homebrew - **Version:** 2.7.0 - **Source summary:** Portable and simple API for accessing AB PLC data over Ethernet - **Homepage:** - **Repository:** - **Generated:** 2026-08-03T19:37:03+00:00 ## Executables - modbus_server (alias) - tag_rw2 (alias) ## Install behavior - Bottle: not available ## Freshness - Page generated: 2026-08-03 - Package-manager version: 2.7.0 ## Project history and usage libplctag is an open-source C library for reading and writing programmable-logic-controller tags over EtherNet/IP and Modbus TCP. It targets industrial automation users who need a small portable API instead of a broad OPC stack. ### Project history 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. ### Adoption history 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. ### How it is used 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. ### Why package nerds care 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. ### Timeline - 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. ### Sources - - - - - ## Security Notes broad file, network, media, or database tool signal. - **Geiger risk:** blue / medium - broad file, network, media, or database tool signal ## Other Package-Manager Records - Nix - libplctag: normalized package name match | nixpkgs package indexes: pkgs/by-name/li/libplctag/package.nix from https://api.github.com/repos/NixOS/nixpkgs/git/trees/master?recursive=1 ## Combined YAML source View the package source record on GitHub. [combined/libplctag.yml](https://github.com/mxcl/pkgdb/blob/main/combined/libplctag.yml) ## Sources - pkg.so package database - Geiger risk classifier - curated package history - pkgdb category and tag curation - external package-manager database matches - cross-ecosystem install command graph