> For the complete documentation index, see [llms.txt](https://infosys.selmotech.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://infosys.selmotech.com/selmo-solution/selmo-solution-en/08-appendix-and-templates/selmo-evidence-for-formal-safety-documentation-and-standards-compliance.md).

# Selmo – Evidence for formal safety, documentation and standards compliance

### Purpose of the document

This documentation clearly and verifiably demonstrates that the application of the **Selmo standard** in the modeling, control and documentation of machines:

* transparently documented and assessed **complete function description** enables,
* the **monitoring of safety-relevant processes** in a structured way,
* and thereby a **legally and standards-compliant implementation** is supported.

***

### 1. Documentability and traceability

Selmo describes every machine **model-based**, in a clear structure:

```
PLANT
└── HWZ (hardware zones)
    └── SEQ (sequences)
        └── Zones (input / output / in-out / mem)
```

Every state, every signal assignment and every safety function is **derivable from the model**. This automatically produces:

* a complete signal directory (IO ↔ Zone ↔ Function),
* a modeled sequence logic (states, transitions, conditions),
* a documented safety structure (CMZ, interlock, MXIC),
* a verifiable restart behavior (reset, synchronization),
* a change log (`Model_ChangeLog.csv`).

This documentation is **machine-readable, version-secure, and revision-capable**.

***

### 2. Formal safety of the functional logic

The model structure ensures that:

* every **Zone** has a documented behavior in every state (`0`, `S`, `i`),
* **Interlocks** lead to immediate reaction upon violation,
* **CMZ signals** are continuously monitored,
* **MXIC releases** allow manual operation only under safe conditions,
* every step is explained by modeled **state transitions** is explainable.

The Selmo model replaces free PLC logic with:

* **deterministic state machines**,
* **fully described signal behaviors**,
* **model-based diagnostics and error display**,
* **automatically derivable restart conditions**.

As a result, **every action, reaction, restriction or diagnosis is explainable and verifiable**.

***

### 3. Monitoring and self-check

During operation the model automatically checks:

| element              | effect in case of deviation                    |
| -------------------- | ---------------------------------------------- |
| `i` (interlock)      | automatic stop, red HMI indication             |
| `S` (sequence check) | waiting state with clear operator guidance     |
| CMZ                  | immediate lock (SEQ, HWZ or PLANT)             |
| MXIC                 | prevention of manual movement with explanation |

**Every violation is displayed in the HMI**, localized and documented – including text and background color. Operator, commissioning engineer and inspector can recognize at any time:

* What the model expects
* Whether the real system meets the state
* Whether a safety violation exists

***

### 4. Standards and legal compliance

The application of the Selmo standard meets the requirements of the following standards and guidelines:

| Standard / regulation         | Fulfillment by Selmo                                         |
| ----------------------------- | ------------------------------------------------------------ |
| **ISO 12100**                 | Modeled operating modes, reset behavior, state management    |
| **EN ISO 13849-1/2**          | Structured safety behavior (CMZ, MXIC, interlock)            |
| **IEC 62061**                 | Verifiable safety functions in sequence structure            |
| **IEC 61508**                 | Functional safety through deterministic model behavior       |
| **IEC 61131-3**               | Generated code fully standard-compliant (ST / GVL / FB)      |
| **Machinery Regulation (EU)** | Technical documentation and diagnostic behavior model-driven |
| **Product liability law**     | Derivability of all functions from verified models           |

Thus Selmo is not only a programming technology – but a **safety-oriented behavior model**, which is automatically linked with CE-relevant evidence.

***

### 5. Legal and audit security

By applying the Selmo model:

* a **traceable functional logic is created**,
* every safety-relevant function is verifiable by model technique,
* a complete technical documentation is automatically generated,
* an independent third party can analyze the function, reaction and limits of the system.

These properties secure: ✅ the **legal certainty for manufacturers**, ✅ the **transparency for customers / operators**, ✅ the **acceptance assurance with authorities / auditors**.

***

### Conclusion

The Selmo method is more than a modeling approach – it is a **formalized structure for safe, documented, traceable machine control**.\
It makes control systems:

* **understandable**,
* **testable**,
* **maintainable**,
* **legally compliant**,
* and **future-proof**.

📌 Compliance with the Selmo structure is an active contribution to risk reduction, quality assurance and compliance with applicable legal regulations.


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