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.
curl -O https://raw.githubusercontent.com/efranceschetti/festo-codesys-mcp/main/.claude/skills/error-diagnosis/SKILL.mdgit clone --depth 1 https://github.com/efranceschetti/festo-codesys-mcpWrote 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.
[](https://agentmods.dev/skills/efranceschetti/festo-codesys-mcp/error-diagnosis)<a href="https://agentmods.dev/skills/efranceschetti/festo-codesys-mcp/error-diagnosis"><img src="https://agentmods.dev/badge/skills/efranceschetti/festo-codesys-mcp/error-diagnosis/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.
<a href="https://agentmods.dev/skills/efranceschetti/festo-codesys-mcp/error-diagnosis"><img src="https://agentmods.dev/badge/skills/efranceschetti/festo-codesys-mcp/error-diagnosis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00087 | $0.00639 |
| Opus 5.5 | $0.00035 | $0.00256 |
| Sonnet 5.5 | $0.00017 | $0.00128 |
| Haiku 4.5 | $0.00009 | $0.00064 |
Grade A, and why
error-diagnosis 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 29 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Error Diagnosis
Never interpret an error code from memory — codes overlap between vendors and profiles.
1. Decode
plc_lookupaction=error_code with the raw code (accepts 0x…, 16#…, decimal) — instant database hit.- Not found ->
explain_error_code(deep search across all topics + all 19 manuals).
2. Contextualize
- Drive/motion fault ->
plc_knowledgeaction=topicfesto-ptp(library error list) or action=read_manualhw-cmmt-servo(recovery procedures, FAQ). - EtherCAT comms -> topic
ethercat-cia402(AL status, ESM transitions). - Anything else ->
plc_knowledgeaction=search with the code AND with symptom words.
3. CODESYS crashes — is it even a code fault?
Two IDE/runtime failure modes are NOT bugs in the ST — do not chase them as error codes. Full runbook: plc_knowledge action=topic codesys-gotchas.
- Cosmetic plugin crash (Festo CPX-E). A red popup
Exception while changing device editor visibility/Fatal error: cannot load module: CPX_E_System/Object reference not set to an instance of an objectinDeviceEditor.OnVisibilityChangedfires when you click theDeviceor a Festo CPX-E node in the device tree. It does NOT block Build, Download, Run, Watch, or Force — click OK and continue; avoid opening those device tabs. Reinstalling the plugin, changing the CODESYS version, or recreating the project does NOT fix it (compiled vendor DLL bug — wait for a vendor update or ignore). - Chronic runtime crash. Use the triage in
codesys-gotchas: probe ports (base-firmware port alive while the runtime ports die = runtime process exception, not power/network); read the device Log (Not matching retain area cleared= persistents wiped); pull the core dump (external abortat erratic addresses = hardware/electrical or compiler↔runtime ABI mismatch, NOT IEC logic — a logic bug logs an IEC exception instead).
4. If truly not found locally
Say so explicitly, then search the web — and suggest saving the finding as a .md in knowledge/manuals/ so it is local next time.
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.
- 1mo ago First seen · 29 lines · 87 tokens per session scan A c54aea56983c
error-diagnosis is a skill published in the GitHub repository efranceschetti/festo-codesys-mcp (2 stars, last pushed 21d ago), licensed MIT. It adds 87 tokens to every session and 639 once invoked, about $0.0003 per session on Opus 5.5. 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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