> 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-structure-and-standard/selmo-technical-standard-and-structure/selmo-method-in-practice/what-do-we-need-to-start-the-ptf-and-from-whom.md).

# 🟢 What do we need to start the PTF – and from whom?

To correctly and completely build a Selmo model in the sense of the PTF concept (**Plant – Task – Function**) at the beginning it needs **clear information and structured inputs** from various stakeholders. Only with these prerequisites can the process model later be implemented deterministically, safely and efficiently.

#### 🔹 1. **What is needed?**

**A. Technical requirements & goals**

* Description of the machine or plant
* Functional requirements (What should the machine do?)
* Quantities, cycle times, variants

**B. Process knowledge**

* Rough description of the sequence (e.g. loading – clamping – machining – unloading)
* Important steps and states
* Dependencies between process steps

**C. Machine structure (possibly preliminary)**

* Division into stations, modules or functional areas
* Overview of actuators, sensors, buttons etc.
* Planned inputs and outputs

**D. Operating requirements**

* Operating modes (e.g. manual/auto, setup mode)
* Safety specifications (e.g. interlocks, emergency stop, CMZ)
* Operating specifications (e.g. HMI functions, start/stop)

**E. Interface requirements**

* PLC (manufacturer, target system, libraries used)
* HMI system or visualization
* Communication interfaces to other systems (e.g. MES, robot)

***

#### 🔹 2. **Who provides this information?**

| Source                                   | Role                                                                   |
| ---------------------------------------- | ---------------------------------------------------------------------- |
| **Customer / Operator**                  | Target specifications, requirements specification, safety requirements |
| **Design (mechanical/electrical)**       | Structure of the machine, actuators/sensors, hardware concept          |
| **Process engineer / process planner**   | Knowledge of the specific machine sequence                             |
| **PLC programmer / automation engineer** | Target architecture for control and communication                      |
| **Safety officer**                       | Interlock specifications, safety-relevant processes                    |
| **HMI/UX responsible**                   | Requirements for the user interface                                    |

***

#### 📌 Conclusion

The start of a Selmo model in the PTF approach is **a structured information gathering process**, in which various disciplines must contribute their perspectives. Only on this basis can a robust, deterministic sequence be modeled and implemented in code – **fully traceable from the requirement to the machine**.


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