GoPLC

A soft PLC written in Go that replaces proprietary industrial programming languages with modern development tools.

Motivation

Industrial automation is stuck in the past. Proprietary IDEs, vendor lock-in, no real version control, and languages that don't transfer to any other domain. If you're going to learn something new anyway, why not use a real programming language with modern tooling? GoPLC lets you write control logic in native Go using VS Code, Git, and CI/CD pipelines instead of being locked into Ladder Logic or Structured Text. It's time to bring software development practices from the last two decades into industrial automation.

Quick Start

Coming soon. Installation and usage instructions will be added as the project develops.

Usage

What is a Soft PLC?

A traditional PLC is a specialized industrial computer that runs control logic for manufacturing equipment. A soft PLC does the same thing but runs on standard hardware—the control software without the proprietary box.

Architecture Overview

GoPLC communicates with industrial devices via standard protocols and exposes data through multiple interfaces:

Input/Output:

• Modbus TCP/RTU for sensors, actuators, and I/O modules
• Automatic reconnection with exponential backoff

SCADA Integration:

• OPC UA server for traditional industrial SCADA systems (Ignition, Kepware, etc.)
• GraphQL API for modern web/mobile integrations
• Optional Zenoh protocol for high-performance pub/sub (Phase 2)

Monitoring:

• Built-in WebUI for real-time monitoring and control
• System health, connection status, variable values, task execution

Variables are defined once in YAML and automatically exposed to all protocols. The runtime handles scheduling, scaling, and protocol translation.

Development Guidelines

Project Structure:

• Registry pattern for extensible protocol support
• Protocol implementations in internal/source/<protocol>/
• Each protocol self-registers via init() functions

Error Management:

• Use structured error format: [Component] - [Description] (context: value, ...)
  • Example: [config] - Unknown source type 'opcua' (source: plc1)
• Each package contains an errors.go file with helper functions
• Use panic() only for programmer errors; return error for runtime errors

Testing:

• Unit tests use table-driven test pattern
• Test coverage required for all error paths

Contributing

Contributions are welcome. If you find a bug or have a feature request, please open an issue. If you want to submit code, please open a pull request with a clear description of your changes.

License

O'Saasy License Agreement - MIT do-whatever-you-want license, but with the commercial rights for SaaS reserved for the copyright holder.