TcView

TcView is a Windows-only VS Code extension for viewing and editing TwinCAT XML-backed PLC source as IEC Structured Text.

It is built as a code-first companion to TwinCAT XAE, not a replacement for it. TcView is strongest when you want faster editing, navigation, diagnostics, metadata inspection, and build workflows from inside VS Code.

Table Of Contents

• Overview
• Current Status
• Why TcView
• Key Features
• Quick Start
• Common Workflows
• Supported Roots
• Supported File Types
• Install
• Bundled Backend
• Key Settings
• Library Metadata
• Documentation
• License

Overview

What TcView Is

• An ST-first editor for TwinCAT XML-backed PLC source files
• A TwinCAT-aware explorer for valid TwinCAT solutions and PLC project roots
• A navigation and diagnostics tool for TwinCAT source authoring
• A quick way to inspect libraries and build the active TwinCAT solution from VS Code

What TcView Is Not

• Not a full TwinCAT XAE replacement
• Not a device or configuration engineering environment
• Not a runtime administration or online-debugging workstation

Use TcView for day-to-day code work. Use TwinCAT XAE for device engineering, activation, deployment, runtime control, and full compiler/runtime truth.

Current Status

TcView is currently in public alpha.

• Windows only
• Built for TwinCAT development workflows inside VS Code
• Suitable for early real-world use, with some features still maturing as the alpha continues

Why TcView

• Edit TwinCAT XML-backed source as readable Structured Text instead of raw XML
• Work from a TwinCAT-aware Explorer grouped into SYSTEM, PLC, and I/O
• Keep diagnostics, navigation, and library inspection close to the code
• Build the active TwinCAT solution without leaving VS Code

Key Features

• Open supported TwinCAT XML artifacts as editable Structured Text
• Save ST changes back into the original TwinCAT XML source
• Browse TwinCAT projects grouped into SYSTEM, PLC, and I/O
• Create TwinCAT files and folders from the Explorer
• Rename, delete, copy, cut, and paste supported TwinCAT items
• Add methods, properties, actions, and transitions for supported POU-like files
• Show diagnostics on files, folders, and top-level Explorer groups
• Navigate with completion, hover, rename, references, symbols, folding, and code actions
• Show per-PLC References and open library references in an API-style viewer
• Resolve libraries from project, .tmc, managed-library, built-in, and user metadata layers
• Import library project metadata from a selected .plcproj or project folder
• Update, remove, and prune user library metadata entries
• Use optional Automation Interface-backed commands to add or remove TwinCAT library references
• Build the active TwinCAT solution with MSBuild
• Export optional runtime performance baselines and traces for troubleshooting

Quick Start

1. Open a real TwinCAT root: a solution root with .sln plus .tsproj or .tspproj, or a standalone PLC project root with .plcproj.
2. Open the TcView activity bar container in VS Code.
3. Use the Explorer view to browse SYSTEM, PLC, and I/O.
4. Open supported TwinCAT source files and edit them as Structured Text.
5. Save normally to write changes back into the original TwinCAT XML file.

Common Workflows

• Open .TcPOU, .TcPRG, .TcDUT, .TcGVL, .TcITF, .TcIO, and related artifacts as ST
• Edit them in a code-first view instead of raw TwinCAT XML
• Save changes back to the original TwinCAT source file
• Expand PLC project nodes and folders
• Inspect References
• Open a library reference in the API-style viewer
• Create TwinCAT folders and files
• Add methods, properties, actions, and transitions where supported
• Rename, delete, copy, cut, and paste supported items
• Review diagnostics in the editor and Explorer
• Use completion, hover, rename, references, symbols, and code actions
• Suppress selected lint rules with supported tcview and Beckhoff analysis pragmas
• Run Build TwinCAT Solution
• Capture troubleshooting artifacts with Export TcView Performance Baseline
• Capture runtime traces with Export TcView Performance Trace

Supported Roots

TcView activates on real TwinCAT roots only.

• TwinCAT solution root:
  • contains .sln plus .tsproj or .tspproj
• Standalone PLC project root:
  • contains .plcproj

A plain .sln without a .tsproj or .tspproj is not treated as a TwinCAT solution.

Supported File Types

Type	Extension
POU	.TcPOU
Global Variable List	.TcGVL
Data Type	.TcDUT
Program	.TcPRG
Application	.TcAPP
Communication	.TcCOM
Variable Container	.TcVAR
I/O	.TcIO
Interface	.TcITF

Install

From VSIX

1. Build or download a .vsix package.
2. In VS Code, run Extensions: Install from VSIX....
3. Select the TcView .vsix.

From Source

1. Run npm install.
2. Run npm run compile.
3. Press F5 in VS Code.

Bundled Backend

Most TcView features run entirely inside the VS Code extension host.

The bundled backend is only required for TwinCAT Automation Interface operations such as:

• Add TwinCAT Library To Project
• Remove TwinCAT Library From Project

Notes:

• The packaged extension ships with a bundled backend.
• The bundled backend currently targets net8.0-windows.
• twincat.backend.executablePath is an advanced override, not a normal setup step.
• If the backend cannot launch, verify the required .NET runtime is installed and capture the exact error text.

Key Settings

Setting	Purpose
twincat.build.msbuildPath	Explicit MSBuild path override
twincat.backend.tmcRoots	Additional .tmc lookup roots
twincat.library.managedRoots	Additional Managed Libraries roots
twincat.library.metadataFiles	Additional library metadata JSON files
twincat.backend.executablePath	Optional override path for a custom TcView backend executable

Library Metadata

TcView resolves libraries from several sources in order of confidence:

1. Project or local source
2. Current PLC .tmc
3. Installed managed-library metadata
4. Built-in catalog metadata
5. User or workspace metadata

In practice:

• some core Beckhoff libraries already ship with built-in metadata
• project-local or internal libraries usually need manual metadata import from source
• .tmc reflects what the current consuming project has compiled or exposed, not a complete external library catalog

Global user metadata lives at:

• %APPDATA%\\TcView\\tcview.libraries.json

For more detail, see Library Metadata.

Documentation

• Architecture
• Branch Protection
• Contributing
• Library Metadata
• Lint Pragmas
• Development
• Performance Baselines
• Performance Trace Triage
• Support Matrix
• GitFlow
• Roadmap
• Security Policy
• Code of Conduct
• Changelog

License

MIT. See LICENSE.