> 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/selmo-as-a-process/selmo-ptf/how-to-do-ptf.md).

# How to do PTF

### Introduction

The **PTF process** (Process – Technology – Function) is the structured way to develop from an idea or task a **fully described, technically traceable and safe machine behavior** to develop.

It forms the core of the methodical approach in modern automation projects:\
from the **analysis of the process** through the **selection of the technology** up to the **description of the functions**, which control the sequence.

The goal is, **to reconcile understanding, documentation and implementation** – before the first line of code is written or hardware is ordered.

***

### Why PTF?

Many projects start with technical solutions before the problem is clearly described.\
The PTF approach reverses the order:

> **First understand – then describe – then automate.**

This creates a common understanding between:

* process engineering
* mechanics / electrical
* Automation / Software
* safety and quality

The result is a **clear, formal model** of the machine behavior that:

* is traceable at any time,
* can be documented in compliance with standards,
* and can be directly transferred into engineering or simulation tools.

***

### The three steps of the PTF process

| Step                  | Goal                                    | Result                             |
| --------------------- | --------------------------------------- | ---------------------------------- |
| **1. Process (P)**    | Understand and describe, *what happens* | process flow, states, behavior     |
| **2. Technology (T)** | Determine, *with what it happens*       | components, interfaces, standards  |
| **3. Function (F)**   | Define, *how it happens*                | function logic, parameters, safety |

***

### Procedure – in brief

{% @mermaid/diagram content="flowchart LR
A\[Prozess verstehen] --> B\[Technologien definieren]
B --> C\[Funktionen beschreiben]
C --> D\[PTF prüfen & freigeben]
D --> E\[Engineering & Umsetzung]" %}

1. **Understand the process**\
   → Clarify product, process, operation and sequence
2. **Define technologies**\
   → Which means, components, interfaces and safety functions are required?
3. **Describe functions**\
   → How will the process be implemented technically? Which parameters, conditions and checks apply?
4. **Review and release PTF**\
   → Completeness, consistency, compliance with standards
5. **Handover to engineering / simulation / documentation**

***

### Result

After carrying out the PTF process there is a **complete technical definition** available:

* documented, traceable and released
* as a basis for process modeling for control, simulation, risk analysis and CE documentation
* and as a common language between all disciplines

***

### In short

> PTF means: **from behavior to function** –\
> logical, technical and safe.


---

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