Selmo structure

📘 Selmo structure – the blueprint for modeled machine logic

The Selmo method is based on a fixed, logical structure with which every machine is built uniformly, modularly and traceably. This structure is the foundation for modeling, code generation, safety functions and documentation.

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🔷 1. Structural overview

scssCopyEditPLANT
└── Hardware zones (HWZ)
    └── Sequences (SEQ)
        └── Zones (Input, Output, In-Out, Mem)

Each level fulfills a clear task and is explicitly visible in the model.

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🧱 2. The four levels in detail

✅ PLANT

• Represents the entire machine or line

• Contains global parameters, safety monitoring (e.g. TCMZ)

• Controls the overarching structure and interfaces (OPC UA, MES)

✅ HWZ – Hardware zone

• Controllable functional unit of the system (e.g. station, module)

• Has its own operating modes: Manual / Auto

• Contains one or more SEQs

• CMZ and safety logic can act at the HWZ level

✅ SEQ – Sequence

• The Core of the modeled machine logic

• Describes the process flow in logical states

• Uses states such as State, Timer, Decision, Repeater

• Is coupled with:

  • Bit control (system layer)

  • parameters

  • safety rules (MXIC, CMZ)

  • HMI texts

✅ Zone

• Link between logic and real technology

• Types:

  • Input → sensor

  • Output → actuator

  • In-Out → actuator with feedback

  • Mem → internal state / marker

• Each zone receives a behavior per state: 0, S, i

• Is documented with: address, function, description, HMI text

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🎯 3. Why this structure?

Advantage	Description
Modularity	Each SEQ is a self-contained process module
Reusability	SEQs can be copied, extended or varied
Diagnosability	Each zone is logically assigned and monitored
Exportability	Documentation (CSV, PDF) is generated automatically from it
safety	Safety functions definable at SEQ, HWZ or PLANT level

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🧾 Conclusion

The Selmo structure is the key to model-based automation. It is uniform, clearly documentable, fully exportable – and ensures that machine behavior, code and documentation always match.

📌 Each modeled machine is thus not only logical – but also verifiable, safe and CE-compliant in its construction.