Discrete Event Control Case Study (TIA Portal)

This repository contains a case study implementation of a Discrete Event Control Architecture for a Siemens SIMATIC PLC workflow using TIA Portal and SCL-based function blocks.

The project combines:

• Discrete event operating logic (modes, interlocks, force states, alarms)
• Analog and digital module templates
• Process behavior simulation blocks for test and validation
• Supporting technical reports and plant description material

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1. Project Scope

The case study focuses on building a modular control structure that is suitable for process units with:

• Manual/Auto operation
• Interlocks and permissives
• Force and safety-oriented override behavior
• Alarm handling and feedback supervision
• Simulation-first validation before deployment

The overall control philosophy aligns with operating mode/state-driven process control concepts used in industrial automation.

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2. Repository Structure

AO_Project Files/
  AO_Project Files/
    DO_Data.udt
    DO_Module.scl
    Do_Sim.scl
    Motor_AO.scl
    Pump Simulation.scl
    Pump_Data.udt
assets/
  images/
docs/
  reports/
archives/
Material/
  Plant Description/
    Festo Plant Description Translated/
PLC SIEMENS/

Additional technical reports and diagrams are available at the workspace root and in Material/.

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3. Main Control Blocks

3.1 DO_Module.scl

Digital output module with:

• Enable gating
• Interlock handling
• Manual/Auto command arbitration
• Force-off priority behavior
• Feedback supervision timers and mismatch detection
• Alarm reporting through DO_Data

3.2 Motor_AO.scl

Analog output module for motor/pump-style control with:

• Enable/Interlock/Manual-Auto operating logic
• Selector-based interlock handling
• Range validation of operator and interlock values
• Force behavior and alarm handling
• Not-following supervision against feedback
• Alarm reporting through Pump_Data

3.3 Pump Simulation.scl

First-order lag process model:

• Simulates pump output response to command value
• Uses configurable Tau, Gain, and Ts
• Includes output limiting and numerical protection

3.4 Do_Sim.scl

Discrete-time thermal-like simulation for digital command response:

• Real elapsed-time-based update
• Temperature-like state response between min/max limits
• Feedback bit generation

3.5 UDTs and Alarm DB

• DO_Data.udt: alarm fields for digital module
• Pump_Data.udt: warning/alarm fields for analog module
• Alarms.db: centralized alarm storage structure

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4. Control Priorities (Design Intent)

The implemented blocks follow a clear priority structure:

1. Disable and safety states dominate normal control behavior.
2. Force conditions override normal commands.
3. Interlocks take precedence over Manual/Auto requests.
4. Manual/Auto command logic applies only when higher-priority conditions are healthy.
5. Supervision and alarm logic monitor consistency between command and feedback.

This pattern improves maintainability and reduces ambiguity during commissioning and troubleshooting.

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5. How to Use in TIA Portal

1. Create/open your SIMATIC project in TIA Portal.
2. Import the SCL sources from AO_Project Files/AO_Project Files/.
3. Import/create UDTs (DO_Data, Pump_Data) before compiling FBs.
4. Create instance DBs for DO_Module, Motor_AO, and simulation FBs.
5. Map physical or simulated I/O to FB inputs/outputs.
6. Download to PLC or run PLCSIM to validate mode changes, interlocks, and alarms.

Recommended validation sequence:

1. Verify Enable/Disable behavior.
2. Verify Force and Interlock priority paths.
3. Verify Manual/Auto transitions.
4. Verify feedback mismatch timing and alarm reset behavior.

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6. Visuals and Diagrams

6.1 AO and DO Logic Views

6.2 Interlock and Feedback

6.3 Simulation Views

6.4 Reference State Graph

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7. Reference Documents

• Material/Control of Discrete Event Systems-Case Study Report.pdf
• Material/Development and Implementation of a Discrete Event Control Architecture for Simatic S7.pdf
• docs/reports/Control Theory.pdf
• docs/reports/Plant Components and Description.pdf

These reports provide the theoretical background, plant-level context, and implementation rationale.

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8. Notes

• File and folder naming currently includes spaces in some locations (for example, DO_Module .jpeg).
• If you plan to automate documentation pipelines, consider normalizing names to avoid path edge cases.
• This README is designed to be a practical entry point for engineers reviewing or extending the case study.