Stop your agent guessing
at TwinCAT code.

On Windows, set your download token and run one PowerShell command. That installs plcsense with Scoop and activates your licence when needed.

$env:PLCSENSE_TOKEN = '<your token>'
irm https://plcsense.com/install.ps1 | iex

If you would rather wire an MCP client through npm: same PLCSENSE_TOKEN, Node.js 18+, Windows x64 today, and still a commercial licence.

$env:PLCSENSE_TOKEN = '<your token>'
npx -y @zeugwerk/plcsense mcp

The download token and licence key come with this round's early access, which is now closed to new signups; if you already signed up, keys are going out on a rolling basis, so yours may still be on the way. Join the launch list for the next round. The installer is plain text, so you can read it before you run it.

Windows, PowerShell and the TwinCAT solution you want to work on. Neither TwinCAT nor XAE has to be installed for plcsense to read your project and its libraries, though it will use your local Managed Libraries folder when there is one, and you can point it somewhere else if your libraries live elsewhere. The npm launcher also needs Node.js 18+.

Cursor, Claude Code, VS Code, Codex, Gemini CLI and Zed. Run the matching setup command in the folder you open in your agent, with your TwinCAT solution in it or below it, and it writes the MCP entry for that client plus a .Zeugwerk/plcsense.json you can point at your documentation. Project-local only: nothing is written to your global agent config.

plcsense setup cursor

plcsense setup <client> writes .Zeugwerk/plcsense.json once, with every knob present and set to its default, so the file itself documents what you can change instead of hiding it in code. Nothing in it is secret, so it is safe to commit alongside the solution.

{
  "config_version": 3,
  "managed_libraries": {
    "root": "C:/TwinCAT/3.1/Components/Plc/Managed Libraries/"
  },
  "doc_sites": {
    "ZCore": { "root_template": "https://doc.zeugwerk.dev/{channel}/" },
    "AcmeSealingLib": { "root": "https://docs.acme.example/sealing/1.4/" }
  },
  "beckhoff_infosys": {
    "enabled": true,
    "cache_ttl_hours": 168,
    "crawl_delay_ms": 10,
    "extra_eligible_namespaces": []
  },
  "confluence": {
    "enabled": false,
    "base_url": "https://your-site.atlassian.net/wiki",
    "spaces": [],
    "library_namespaces": {}
  },
  "parser": { "backend": "TreeSitter" },
  "libraries": {
    "transitive_references": true,
    "max_depth": 8,
    "max_libraries": 250,
    "wrapper_hint_names": ["ZPlatform", "ZAux"],
    "hydration_profile": "signatures"
  },
  "validation": {
    "semantic_checks": true,
    "disabled_checks": []
  }
}

config_version

Stamp on the shipped preset, not a product version number. setup only rewrites a file whose stamp is behind the current one, and asks first unless told otherwise.

managed_libraries.root

TwinCAT's own Managed Libraries folder. Already resolves %TWINCAT3DIR% by default; set it only if your libraries live somewhere else.

doc_sites.<Namespace>

Where a library's zkdoc output lives, per library namespace, so get_plc_type_documentation reads the version your project actually references. root_template resolves a {channel}/{version} placeholder from that version; root is a fixed URL for a site that does not version its docs.

beckhoff_infosys.*

On by default, pulling official Beckhoff pages for Beckhoff libraries. cache_ttl_hours and crawl_delay_ms are cache and politeness knobs; extra_eligible_namespaces is an escape hatch for a library that carries no Tc2_/Tc3_ name and no distributor tag.

confluence.*

Off until you set enabled. base_url and spaces scope the opt-in Confluence Cloud lane; the token itself is an environment variable, never a line in this file.

parser.backend

TreeSitter by default; Antlr is the fallback grammar engine.

libraries.*

How far library hydration follows references: transitive_references, max_depth and max_libraries bound the walk; wrapper_hint_names flags your own wrapper convention to a validation check; hydration_profile is "signatures" (default, no method bodies) or "full" (source libraries keep their bodies too).

validation.*

semantic_checks turns the extra checks off entirely, for when one misfires more than it helps; disabled_checks silences a single rule code instead.

Everything here already works with no edits. doc_sites is the one most people touch by hand, to point plcsense at their own libraries' documentation.

No. There is no LSP, no inline completions, no diagnostics in your editor: plcsense only answers when an agent calls one of its MCP tools. But if you are asking, you have already found the real problem: agents guess on TwinCAT code because nothing gives them the grounded, semantic view of a solution and its libraries that a language server gives for mainstream languages. That is the gap plcsense closes, as an MCP tool rather than an LSP. Tell us what you are working on in the launch list form: understanding that distinction already puts you ahead of most people asking for a demo.

Not on a one-line change to a function block you already know, sitting in the open file. Reading that file is enough there, and an agent guessing from the screen looks just as good.

You notice it the moment the work leaves that file. That includes a few lines against a sibling type, a library you have not called yet, an interface with more than one implementer, a rename across many POUs, or a project someone else wrote.

A text search or the .tmc from your last TwinCAT build can still look correct for names already on that project's symbol tree. Neither covers a helper that exists only on a sibling, the rest of a library you have not called, which override actually runs, or a single view across several PLC projects. find_plc_implementations and find_plc_references answer by type, not by text.

The failure this catches is often a line that looks like Structured Text and does not compile: the method exists, just not on that type. It is also a rename that still compiles with one call site quietly left untouched.

Not today: TwinCAT 3 is what we test on and what we support. Very little of the engine is Beckhoff-specific though. It parses IEC 61131-3 Structured Text, and what knows about a vendor is the layer that finds projects and resolves libraries. For a toolchain that keeps its sources as plain ST files that layer is the whole job, so SIMATIC AX code itself would largely be reachable, while what its packaged libraries contain would not. CODESYS needs its sources readable on disk, so an export rather than the binary project file. Tell us in the form which one you are on: what we do after TwinCAT is exactly the sort of thing the pilot decides.

Not yet. Nothing in the analysis needs Windows, but Windows is the only build we package today, so that is the honest answer for early access. Tell us in the form if another platform is what stands between you and using it, because that is the kind of thing the pilot is meant to decide.

Scoop: scoop update plcsense, or re-run the installer. npm: the next npx -y @zeugwerk/plcsense picks up the published version. Expect to update often during early access.

scoop update
scoop update plcsense

Open your own solution and ask about a library you depend on but have not called from yet. That is the case a text search or the .tmc from your last build cannot cover, because the rest of that library never made it onto this project's own symbol tree.

"How do I call FB_SealHead from AcmeSealingLib? What are its methods and parameters?"
"Which types in this project implement [an interface from a library we use]?"
"What are the valid values of E_SealPhase in the AcmeSealingLib version we reference?"
"Where is ST_SealDose used across this solution?"
"Validate this project and fix whatever it finds."

Those are close to the demo output at the top of this page, on purpose: the same tools answer them on your own solution.

This round of early access is closed to new signups, and we are sending out its licence keys on a rolling basis - everyone in it should have theirs soon. Leave your details in the launch list and we will write when plcsense is publicly available, or sooner if a spot opens before then.