Comparison to classical control development

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🔄 Classical way: Open loop with many breaks

In a classic PLC project it typically goes like this:

1. Requirements are defined

2. An expert translates them manually into PLC code

3. The code is tested – does it match the requirement?

4. Documentation is created separately – usually afterwards

5. When changes occur:

   • Adjust code

   • Update documentation

   • Re-run tests

   • Review by a specialist required

6. Result: An open loop

   • high effort for review, traceability, maintenance

   • any deviation in operation requires manual intervention

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🧠 Selmo & SDEA: Closed, automated loop

With Selmo it works differently – structured and end-to-end:

1. Requirements are formulated as a process model (SDEA) formulated

2. From this are generated automatically:

   • the control (logic, states, transitions)

   • the Monitoring (bit control, CMZ, interlock, MXIC)

   • the Documentation (signal directory, sequence, safety functions)

3. Code and HMI are generated directly from the model

4. Changes in the requirement → Update model → everything adapts

5. In operation:

   • the model checks the machine in real time

   • no undefined states

   • automated fault diagnosis & documentation

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🎯 Conclusion: Difference in depth

Aspect	Classical	Selmo with SDEA
Requirements	manually translated into code	directly modeled
Code review	by experts	automatically validated
Documentation	retrospective and costly	automatically from model
Changes	error-prone, costly	simple via model change
Real-time behavior	hard to verify	formally monitored by the model
States	often open, implicit	deterministic and visible
CE evidence	manually assembled	structured, directly derivable

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With Selmo and the SDEA model a closed, audit-proof loop, in which logic, behavior, safety, operation and documentation are always synchronized – and any deviation is detected immediately is.

📌 Selmo replaces testing effort with model clarity – and makes automation traceable, scalable and safe.

🆕 Chapter: Comparison to the classic PLC – methodology & behavior

What is Selmo (SDEA) compared to the classic PLC?

Criterion	Classic PLC	Selmo (SDEA model)
Sequence logic	via code, jump markers, conditions	via modeled states and transitions
Control logic	distributed in the code	central in the model (logic layer)
Signal behavior	programmed directly (e.g., set/reset)	modeled via bit control (0, S, i)
Safety behavior	manually programmed	modeled (interlock, CMZ, MXIC)
Manual mode	via auxiliary logic and button handling	automatically released/locked by MXIC
Operator diagnosis	created manually	automatically from the model (texts, colors, zone display)
Restart	programmed individually	model-driven with synchronization and reset
Documentation	manually or externally	automatically generated from the model

Advantages of the Selmo approach

• Clarity: Model instead of code – everyone sees what is happening

• safety: Structured CMZ and MXIC logic

• Maintainability: every change documented traceably

• Fault tolerance: Diagnosis comes directly from the model

• CE conformity: Operating modes, reset logic, safety reactions representable

With Selmo a consistent behavior is created – from the sensor to the HMI display, documented and testable.