zkdoc (zkdoc-action)

One of Zeugwerk’s CI/CD tools for TwinCAT. Keeping PLC docs in sync with code is hard when everything is manual. zkdoc generates HTML API docs from your PLC source -write comments in code, push, and publish (e.g. to GitHub Pages) without running DocFX or zkdoc yourself. zkdoc-action is available for all major Git hosts (GitHub, GitLab, Bitbucket) and runs on our CI/CD. For on-premises or licensed use, see zkdoc. Comment syntax: Syntax reference.

Why use it

Docs from source - API reference and comments stay in sync with code.
Professional output - API docs, examples, and structure in one site.
Low maintenance - Builds on every push; no manual doc updates.
Searchable - Generated site is indexed and searchable.
Deploy anywhere - GitHub Pages, your own server, or any HTTP host.

Quick start

Register - Contact us to register. Public repos get 30 free builds/month.
Add a workflow - The example below is for GitHub; zkdoc-action also works with GitLab CI and Bitbucket Pipelines. Create .github/workflows/docs.yml (or the equivalent in your Git host):

name: Documentation
on:
  push:
    branches: [main, develop]
  workflow_dispatch:
jobs:
  build-docs:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Generate Documentation
        uses: Zeugwerk/zkdoc-action@v1
        with:
          username: ${{ secrets.ZEUGWERK_USERNAME }}
          password: ${{ secrets.ZEUGWERK_PASSWORD }}
          filepath: '.'
      - name: Deploy to GitHub Pages
        uses: peaceiris/actions-gh-pages@v3
        with:
          deploy_key: ${{ secrets.ACTIONS_DEPLOY_KEY }}
          publish_dir: archive/docs/html

Secrets - Set ZEUGWERK_USERNAME and ZEUGWERK_PASSWORD in GitHub Secrets. For GitHub Pages, configure a deploy key (see peaceiris/actions-gh-pages).
Push - Docs build and deploy on every push (or on manual run).

How it works

Your TwinCAT code (with comments) → Git push → zkdoc-action runs on Zeugwerk CI/CD → PLC source is parsed, comments and symbols extracted, DocFX generates HTML → output is in archive/docs/html. Your workflow can then deploy that folder (e.g. to GitHub Pages).

Writing docs in your code

Use /// above POUs, methods, and declarations, and //< next to variables. Full syntax, cross-references, and DocFX options: Syntax reference.

Configuration

Inputs

Input	Required	Description
`username`	Yes	Zeugwerk account username
`password`	Yes	Zeugwerk account password
`filepath`	Yes	Path to `.plcproj` or folder containing `.Zeugwerk/config.json`
`doc-folder`	No	Folder with custom `docfx.json` (e.g. `docs/`)

Outputs

Artifact	Location
HTML docs	`archive/docs/html/`
Build logs	GitHub Actions UI

Filepath

Single PLC - filepath: 'MyPlcProject/MyPlcProject.plcproj'
Zeugwerk / Twinpack projects - filepath: '.' so the action discovers and uses .Zeugwerk/config.json.

Example

struckig: repo, generated docs, workflow.

Pricing

Free - 30 builds/month for public repositories.
Commercial - Custom pricing for private repos. contact us.

Troubleshooting

Docs not generating - Ensure filepath points to a valid .plcproj or a directory with .Zeugwerk/config.json. Check the Actions logs.
GitHub Pages not updating - Verify deploy key and GitHub Pages settings (see peaceiris docs).
Layout or content wrong - Check docfx.json and comment syntax in Syntax reference.

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