⚖️ Responsibilities in the Selmo process

1st Principle

Selmo is a formal method for defining and implementing machine behavior – comparable to the technical drawing in mechanical engineering and the circuit diagram in electrical engineering.

Selmo describes, how a process should run technically and logically correctly, not, which process is sensible in content or which hardware works physically.

Selmo is a language, not an engineer.

Responsibility for content, execution and outcome remains with the subject-matter disciplines and the economic operator.

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2. Roles and responsibilities in the project

Discipline / Role	Area of responsibility	Responsibility according to Selmo
Requirement issuer / Customer	Definition of the desired process, function and objective	Provides complete and verifiable requirements (PTF-REQ). Must authorize changes to the process or the function.
Process owner (Industrial Engineering)	Process description, cycle time, parameters, states, functional requirement	Has the process knowledge. Must ensure that the described process is actually executable.
Mechanics / Mechanical Engineering	Mechanical implementation, assemblies, kinematics, end positions	Responsible for functionality and safety of the physical components.
Electrical / Control (E-Plan)	Electrical planning, I/O structure, protective circuits, safety engineering	Responsible for power supply, signal availability and standards-compliant wiring.
Automation / Software (Selmo modeler)	Implementation of the PTF requirements into the Selmo process model	Responsible for formal correctness, completeness and determinism of the control logic.
PTF lead / Project management	Overall coordination, documentation, quality, interfaces	Responsible for completeness, approvals and project conformance (PTF ↔ model).
Quality / Safety / CE	Review of standards conformity, risk assessment, approval	Responsible for CE conformity, safety evidence and risk documentation.
Economic operator (machine/plant manufacturer)	Bringing together all disciplines into a functioning machine	Bears the overall responsibility for meeting customer requirements, safety and intended operation.

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3. Principle of responsibility according to Selmo

Selmo brings responsibility and traceability into a clear sequence:

1. PTF describes the responsibility of the definition → The process is described, reviewed and approved. → Any uncertainty must be clarified here, not later in the code.

2. Process model describes the responsibility of the implementation → The logic is modeled so that it is deterministic and formally correct. → Errors in the logic or deviations from the specification are immediately visible.

3. Code and control describe the responsibility of the execution → If the code deviates from the model, this is a violation of the approval. → Changes must be traceably entered in the model and in the PTF.

4. Operation and service describe the responsibility of the use → The operator uses a formally documented, reviewed system. → Any change to behavior must be documented via change management.

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4. Exemplary analogy

Comparison	Mechanical engineering	Electrical engineering	Automation (Selmo)
Formal basis	Technical drawing	Circuit diagram	Process model
Tool	CAD system	EPLAN	Selmo Studio
Description	Geometry, tolerances, movement	Circuit, wiring diagram, I/O	States, logic, signals, safety
Test equipment	Dimensional inspection, CAD validation	Continuity test	Logic validator, simulation
Deviation	Part does not fit → check drawing	Signal missing → check circuit diagram	Behavior wrong → check process model
Reaction	Adjust the drawing or rework	Adjust the circuit diagram or wiring	Adjust the process model or PTF

Selmo follows the same principle as design: A deviation in reality does not lead to a “workaround in the field”, but to an adjustment of the formal description.

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5. Handling deviations

Case A – Deviation in the code

• If it is found during commissioning or testing that the code does not correspond to the process model, → the code must not be manually corrected, → but the Process model adjusted and regenerated.

• Every change is documented and versioned (audit trail).

Case B – Hardware deviation from the specification

• If sensors, actuators or interfaces do not correspond to the PTF definition, → the technology description (PTF-TECH) is adjusted. → Only after this adjustment may the model be updated.

Case C – Non‑Selmo‑compliant implementation

• If the machine builder implements parts of the plant not in Selmo-compliant manner, e.g. incomplete logic, missing CMZ or manual “special functions”, → this is marked in the PTF as “Non‑Selmo‑compliant” marked. → These functions are not formally verifiable, → they are considered documented risk, → and the responsibility lies with the Marketing authorization holder or with the customer.

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6. Responsibility for the process

The process owner defines, what what is to be achieved. Selmo ensures that how it is implemented deterministically, safely and documented. The Marketing authorization holder bears the responsibility that the machine as a whole – mechanics, electrics, control and process – executes the defined behavior safely and in compliance with standards.

Selmo cannot compensate for faulty engineering.

However, it can make it visible – and thereby turn uncertainty into a documented responsibility.

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7. Limits of the method

Selmo guarantees:

• formal correctness of the process model,

• deterministic execution,

• automatic traceability,

• safety through CMZ / MXIC / interlock logic,

• complete documentation.

Selmo does not guarantee:

• the technical functionality of the hardware,

• the physical feasibility of a process,

• the completeness or logic of the customer-side requirements,

• the quality of the installation or commissioning,

• the responsibility of the economic operator for safety and liability.

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8. Responsibility in case of error

Situation	Assessment	Responsible
Logic error in the model	formal error, visible in the validator	Selmo modeler / Automation
Function deviates from the PTF	Deviation from the specification, to be documented	Process owner / PTF lead
Hardware does not function as specified	fault in execution / integration	Mechanics / Electrical / Economic operator
Non‑Selmo‑compliant logic or bypass	documented risk, not verifiable	Economic operator / Customer
Deviation discovered only during commissioning	Failure in PTF or model review	Project management / PTF lead

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9. Conclusion

Selmo does not replace the responsibility of the engineers, but gives them a tool to carry it out demonstrably.

Selmo makes visible,

• where a process was correctly described,

• where an implementation was carried out correctly,

• and where deviations or risks exist.

Thus a engineering system is created that structures responsibility – from the customer to the economic operator.

Selmo stands for:

• formal language, not interpretation,

• traceability instead of assumption,

• correction in the model instead of improvisation in the code,

• and documented responsibility instead of scapegoating.

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In short:

Selmo is the CAD system for logic.

It draws, checks, documents and proves the behavior – but it does not replace the designer.

Responsibility remains human – Selmo only makes it finally visible and traceable.