TcTidier

TcTidier is a formatter for TwinCAT Structured Text in VS Code.

It formats common TwinCAT PLC source files, plain Structured Text files, and TwinCAT-oriented virtual documents so you can keep TwinCAT code readable and consistent without hand-tuning spacing and indentation.

What It Formats

• .TcPOU
• .TcGVL
• .TcDUT
• .TcIO
• .st
• .iecst
• TcView virtual Structured Text documents opened as twincat / iec-st

Features

• Format the active TwinCAT / Structured Text document
• Format an entire workspace of supported TwinCAT files
• Use it from Format Document, the command palette, the editor toolbar, or the status bar
• Set it as the default formatter for TwinCAT Structured Text
• Configure formatting through a workspace .tctidier.json
• Respect ignore directives with tctidier-ignore, tctidier-ignore-start, and tctidier-ignore-end

Quick Start

Install the extension, open a supported file, and either run Format Document or set TcTidier as the default formatter.

Recommended VS Code settings:

{
  "[twincat-st]": {
    "editor.defaultFormatter": "CodePiercerTechnologies.tctidier",
    "editor.formatOnSave": true
  }
}

If another extension opens TwinCAT Structured Text as iec-st, TcTidier can still format it.

Commands

• TcTidier: Format Current Document
• TcTidier: Format Workspace TwinCAT Files

Configuration

Create a .tctidier.json file in your workspace root when you want to customize formatting behavior.

Example:

{
  "indent": 4,
  "useTabs": true,
  "alignDeclarations": true,
  "alignAssignments": true,
  "alignNamedParameters": true,
  "blankLineBetweenCaseBranches": true,
  "normalizeOneLineIf": true,
  "printWidth": 100
}

For the fuller option set and behavior notes, see the formatter guide below.

Notes

• Workspace formatting skips dirty files so unsaved work is not overwritten.
• TcTidier is designed for deterministic formatting rather than style-by-style presets.

More Docs

• Formatter Guide
• Project Quickstart
• Contributing
• GitFlow
• Changelog

License

MIT. See LICENSE.