Layer concept

📘 The layer concept in Selmo

The Selmo system is structured in three layers – in so-called layers. Each layer fulfills a clearly defined function:

• Logic Layer – describes the sequence

• System Layer – defines the behavior of the signals

• Parameter layer – manages data such as times, counters, values

This separation creates transparency, verifiability and reusability – from the model to code generation.

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🔷 1. Logic Layer – the sequence plan

The Logic Layer is the centerpiece of the model. Here the process is described in states.

element	Function
State	normal state (e.g. “clamp part”)
Timer	automatically continue after a defined time
Decision	conditional branching (e.g. sensor ok?)
Repeater	repetition loops (e.g. “up to max. 3 attempts”)
Jump	jump to another state (e.g. in case of error)
Sequence cross	synchronous transition to another SEQ

The Logic Layer forms the deterministic automaton (SDEA) – i.e. a fully describable sequence, free of side effects.

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🔷 2. System Layer – bit control & zone behavior

The System Layer determines how each zone should behave in each state. It consists of a matrix (bit control) in which:

• the rows are states,

• the columns are zones,

• and each cell position contains an operand carries:

Operant	Meaning
0	Zone is inactive in this state
S	sequence check – zone is actively expected
i	interlock – zone must be fulfilled, otherwise stop

Additionally, the following are:

• HMI texts

• colors

• safety linkages (CMZ, MXIC) are automatically generated from the System Layer.

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🔷 3. Parameter Layer – data logic

The Parameter Layer allows non-binary values to be integrated into the model – e.g.:

• times (TIME)

• counters (INT)

• flags (BOOL)

• positions (REAL)

Each parameter can be used as:

direction	Function
IN	adjustable by the operator (e.g. cycle time)
OUT	determined by the system (e.g. actual time)
IN/OUT	combinable (e.g. teachable setpoints)

Parameters can:

• be used in states (e.g. timer time)

• be displayed or modified in the HMI

• communicate via OPC UA or MES interfaces

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🎯 Advantages of layer separation

Advantage	Meaning
Clarity	Each function has its defined level
maintenance	Changes affect only the affected layer
export	Each level produces its own documentation
Modularity	Layers can be reused between projects
Validation	Logic, signal behavior and data checking clearly separated

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✅ Conclusion

The layer concept makes Selmo clean, maintainable, extendable and traceable.

📌 Logic → defines the sequence, 📌 System → secures the behavior of the technology, 📌 Parameter → provides values for variability, performance and interface.