What is festo-codesys-mcp CLAUDE.md?

A set of instructions for using a server that helps program Festo/CODESYS programmable logic controllers (PLCs), which control industrial machines. It covers Structured Text, PLCopen XML, task routing, and project memory.

Writing and editing PLC programs, creating function blocks and data types, diagnosing errors, controlling servo or stepper motors, connecting EtherCAT devices, and building HMIs or gateways.

It keeps the coding agent grounded in the project's local manuals and reusable code instead of relying on uncertain general knowledge. It also directs different PLC tasks to the relevant workflow.

How efranceschetti/festo-codesys-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to efranceschetti/festo-codesys-mcp. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/efranceschetti/festo-codesys-mcp/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/efranceschetti/festo-codesys-mcp

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/efranceschetti/festo-codesys-mcp/claude-md/github.svg)](https://agentmods.dev/instructions/efranceschetti/festo-codesys-mcp/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/efranceschetti/festo-codesys-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/efranceschetti/festo-codesys-mcp/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/efranceschetti/festo-codesys-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/efranceschetti/festo-codesys-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 657 This file is loaded in full into every session.

When invoked 657 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00657	$0.00657
Opus 5	$0.00329	$0.00329
Sonnet 5	$0.00131	$0.00131
Haiku 4.5	$0.00066	$0.00066

Measured 9d ago against content hash 5d235c30c1a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

festo-codesys-mcp CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 49 lines

How it starts

The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.

FestoCodesysMCP — CODESYS PLC Programming Server

MCP server that generates IEC 61131-3 Structured Text and PLCopen XML for Festo/CODESYS PLCs. Embedded knowledge base (BM25 search), 19 device manuals, and a 38-block ST library (30 Function Blocks + 8 shared DUTs).

Golden Rules

Local first. Every Festo/CODESYS/EtherCAT/PLCopen fact comes from the MCP tools (plc_lookup, plc_knowledge, plc_library) — never from memory, never from the web without checking locally first.
Follow the "Next:" hints appended to tool results — they encode the pipeline.
Reuse before create; validate before deliver. (Enforced by the skills below.)

Task Routing

Task	Skill (auto) / entry point
Write/edit any ST code, create FB/PRG/DUT/GVL	`writing-st-code` skill · `/start-fb`
Generate/validate/import PLCopen XML	`plcopen-xml` skill · `/xml-pre-import`
Error codes, faults, diagnostics	`error-diagnosis` skill · `/error-decode`
Servo/stepper, EtherCAT, CiA 402	`motion-control` skill
Web HMI, OPC UA, gateways, CDPX	`hmi-gateway` skill
Adapt a library block	`/fb-from-library`
Naming audit of a folder	`/audit-naming`
End-to-end smoke test of the MCP	`/cycle-test`

Subagents

plc-reviewer (sonnet) — structured review of .st/.xml files; delegate after creating or editing POUs.
xml-validator (haiku) — fast import-gate verdict on PLCopen XML; delegate before any CODESYS import.

Project Memory

.claude/memory/ accumulates durable project context. Read MEMORY.md at the start of substantial sessions. Write when you learn something durable:

hardware present (PLC, drives, IO) -> hardware.md
FBs/POUs created for THIS project -> project-blocks.md
design decisions and their why -> decisions.md
diagnosed error codes + fixes -> errors-solved.md Keep entries dated, one line each. Never store credentials or personal data.

Contributing to the server itself

Build npm run build · test npm test (676 tests) · lint npm run lint
VSCode: Ctrl+Shift+B build task; ST snippets (fbnew, state, errfb).
Tool descriptions follow the USE WHEN / ALWAYS BEFORE / DO NOT pattern (src/tools/*.ts). Next-step hints live in src/utils/next-steps.ts.
Server instructions (src/server-instructions.ts) are the client-agnostic contract; this file covers Claude-Code-specific layers only. Do not duplicate content between them.

Read the full file on GitHub · 49 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

9d ago First seen · 49 lines · 657 tokens per session scan A 5d235c30c1a8

Subscribe to this mod's changes

festo-codesys-mcp CLAUDE.md is an instructions file published in the GitHub repository efranceschetti/festo-codesys-mcp (1 stars, last pushed 3d ago), licensed MIT. It adds 657 tokens to every session, about $0.0033 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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