🟢 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)

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🔹 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

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📌 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.