Requirements for the realization of a machine with Selmo

Purpose of the document

This document describes the mandatory technical, structural and process-related requirements for a machine that is to be Selmo standard modeled, implemented and documented.

It serves as:

• Basis for technical realization (mechanics, electrical, control)

• Basis for specification, planning and system design

• Template for validation and verification

• Evidence in terms of CE conformity

• Interface between design, electrical planning, software development and documentation

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1. General prerequisites

• The machine behavior must be fully modelable be.

• Every sequence must be describable in logical states be (state machine).

• All safety-related signals must be representable as zone in the model be.

• No functions may be implemented outside the model.

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2. Technological requirements

Sensors

• All relevant end positions and states must be detectable by sensors be.

• Sensors must be uniquely assignable and safely evaluable be.

• Redundancy must be provided for safety-relevant sensors (e.g. door contacts).

Actuators

• Actuators must be switchable digitally and, if applicable, provide feedback.

• Movements must be clearly completed or securable via interlock.

Safety interfaces

• Emergency stop, main air, door contacts etc. must be CMZ representable.

• Faulty states must completely lead to an automatic stop lead.

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3. Structural specifications

Machine structure according to Selmo

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

Requirements

• Each subprocess must be modeled in at least one Sequence .

• Each zone must serve exactly one purpose (sensor, actuator, logic).

• Each zone receives behavior in the state (0, S, i) via bit control.

• Zones must be documented unambiguously to IO, address, terminal.

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4. Process and functional logic

Modelability

• Every step of the process must be formulable as a state with defined function .

• There must be no hidden logic or jumps outside the model.

Safety behavior

• Interlocks (i) must be set when a condition mandatorily must be fulfilled.

• CMZ signals must be constantly monitored.

• MXIC must be present for each manual zone.

Restart

• System must be able to be returned to a definable start state.

• Reset may only occur when all fault conditions have been eliminated.

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5. Requirements for engineering and code

Control system

• PLC must support IEC-61131-3 (Structured Text preferred).

• Project structure must be representable with GVL, POUs and standardized blocks.

Code generation

• There must be no manually created code sections outside the Selmo model.

• Changes to the sequence must be traceably documented in the model.

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6. Requirements for documentation and testing

Documentation

• Signal directory with Zone ↔ IO ↔ Address ↔ Terminal

• Model structure with Plant / HWZ / SEQ / Zone

• Parameter list, bit control, CMZ-, MXIC matrices

• Change log: Model_ChangeLog.csv

Validation

• Each SEQ must be validated by a test protocol .

• Error cases (Interlock, CMZ, MXIC) must be specifically tested .

Verification

• Structure must match requirements from CE documentation

• Reset/restart behavior, operating modes and safety logic must be verifiable

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7. Summary: Requirements for the release of a Selmo machine

Domain	Must be fulfilled
Model structure	Fully mapped (Plant → HWZ → SEQ → Zone)
Signal assignment	Documented, verifiable, unambiguous
Safety logic	CMZ, MXIC, interlock modeled and tested
Sequence control	State-driven, deterministic, testable
Restart / reset	Safe, documented, traceable
Documentation	Automatically generated from model, audit-proof
CE demonstrability	Interfaces for risk analysis fully available

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These requirements are mandatory for every project implemented with the Selmo system. They provide the basis for:

• technical quality

• formal verifiability

• standards-compliant safety

• audit-proof implementation

📌 Compliance is a prerequisite for project acceptance, CE approval and long-term maintainability.