PLC DevOps Tools

A complete DevOps toolchain for PLC projects supporting CODESYS, Rockwell/Allen-Bradley, and Siemens TIA Portal / AX platforms. Export, diff, merge, and import with full support for additions, modifications, and deletions.

Why These Tools?

Problem: CODESYS V3.x GUI PLCOpenXML export/import is broken - exported XML files cannot be re-imported reliably.

Solution: Use the CODESYS Scripting API which:

✅ Direct project manipulation (no broken export/import cycle)
✅ Full text-based workflow for version control
✅ Supports additions, modifications, AND deletions
✅ Can run headless for CI/CD
✅ Authoritative imports (import directory is source of truth)

Quick Start (PowerShell Driver Scripts)

CODESYS Projects

Export Project

# From PLCOpenXML file (no CODESYS needed)
.\codesys-export.ps1 -FromXml "MyProject.xml" -OutputDir ".\export"

Rockwell/Allen-Bradley Projects

Export L5X Files

# Export single L5X file
.\l5x-export.ps1 -Input "Motor_Control.L5X" -OutputDir ".\export"

# Export all L5X files in directory
.\l5x-export.ps1 -Input ".\PLC" -OutputDir ".\export"

Siemens TIA Portal / AX Projects

Parse Siemens ST Files

# Parse a single Siemens ST file
.\siemens-export.ps1 -Input "conveyorControl.st"

# Parse all ST files in a directory
.\siemens-export.ps1 -Input ".\siemens_project"

# Parse and run ontology analysis
.\siemens-export.ps1 -Input ".\siemens_project" -Analyze

Generate Diff

.\codesys-diff.ps1 -BaseDir ".\export_v1" -TargetDir ".\export_v2" -OutputDir ".\diffs"

Apply Diff (Merge)

.\codesys-apply.ps1 -DiffDir ".\diffs" -TargetDir ".\export" -OutputDir ".\merged"

Import to Project

# Preview changes first
.\codesys-import.ps1 -ProjectPath "MyProject.project" -ImportDir ".\merged" -DryRun

# Apply changes
.\codesys-import.ps1 -ProjectPath "MyProject.project" -ImportDir ".\merged"

Complete Merge Workflow

# One command to apply diffs and import
.\codesys-merge.ps1 -DiffDir ".\diffs" -TargetDir ".\export" -ProjectPath "MyProject.project" -DryRun

Project Structure

.
├── codesys-export.ps1    # Driver: Export CODESYS project to text files
├── codesys-diff.ps1      # Driver: Generate diffs between exports
├── codesys-apply.ps1     # Driver: Apply diffs to exports
├── codesys-import.ps1    # Driver: Import text files to CODESYS project
├── codesys-merge.ps1     # Driver: Complete merge workflow
├── l5x-export.ps1        # Driver: Export Rockwell L5X files to text
├── siemens-export.ps1    # Driver: Parse Siemens ST files
├── scripts/              # Python implementation
│   ├── codesys_export.py           # Export (runs in CODESYS)
│   ├── codesys_export_from_xml.py  # Export from PLCOpenXML
│   ├── codesys_import.py           # Import (runs in CODESYS)
│   ├── codesys_import_external.py  # Import wrapper (headless)
│   ├── codesys_diff.py             # Generate unified diffs
│   ├── codesys_apply.py            # Apply diffs to text files
│   ├── l5x_export.py               # Export Rockwell L5X files
│   └── siemens_parser.py           # Parse Siemens TIA/AX ST files
├── PLC/                  # Sample Rockwell L5X files
├── legacy/               # Deprecated XML-based tools
├── tests/                # Test files and outputs
└── docs/                 # Documentation

File Formats

CODESYS Exported Text Files (.st)

Extension	Type
`NAME.prg.st`	Program
`NAME.fb.st`	Function Block
`NAME.fun.st`	Function
`NAME.gvl.st`	Global Variable List
`POU_METHOD.meth.st`	Method (in POU)

Rockwell/Allen-Bradley Exported Files (.sc)

Extension	Type
`NAME.aoi.sc`	Add-On Instruction
`NAME.udt.sc`	User Defined Type

Siemens TIA Portal / AX Source Files (.st)

Construct	Maps To
`CLASS ... END_CLASS`	Function Block (FB)
`TYPE ... STRUCT ... END_TYPE`	User Defined Type (UDT)
`PROGRAM ... END_PROGRAM`	Program
`CONFIGURATION ... END_CONFIGURATION`	Configuration (tasks, I/O mapping)
`METHOD ... END_METHOD`	Routine (within a CLASS)
`NAMESPACE ... END_NAMESPACE`	Grouping / package

Diff Files

Extension	Meaning
`*.diff`	Unified diff (modifications)
`*.added`	New file content
`*.removed`	Marker for deletion
`diff_summary.txt`	Summary statistics

Workflow Examples

1. Version Control Workflow

# Export current state
.\codesys-export.ps1 -FromXml "Project.xml" -OutputDir ".\v1"

# Make changes in CODESYS, export again
.\codesys-export.ps1 -FromXml "Project_modified.xml" -OutputDir ".\v2"

# Generate diff for review/commit
.\codesys-diff.ps1 -BaseDir ".\v1" -TargetDir ".\v2" -OutputDir ".\changes"

2. Merge Changes from Branch

# You have: diffs from feature branch, current project export
.\codesys-merge.ps1 `
    -DiffDir ".\feature_diffs" `
    -TargetDir ".\current_export" `
    -ProjectPath "MyProject.project" `
    -DryRun  # Preview first!

3. Add New Variables to GVL

# Edit GVL.gvl.st in your text editor, then import
.\codesys-import.ps1 -ProjectPath "MyProject.project" -ImportDir ".\modified"

4. Export Rockwell L5X Files for Version Control

# Export all L5X files from PLC directory
.\l5x-export.ps1 -Input ".\PLC" -OutputDir ".\export"

# Commit the .sc files to version control
git add export/
git commit -m "Add PLC logic from Rockwell project"

Rockwell/Allen-Bradley L5X Export

The L5X export tool converts Rockwell Logix 5000 L5X files to structured code (.sc) format for version control and code review.

What Gets Exported

Add-On Instructions (AOIs): Complete instruction definitions including parameters, local tags, and ladder logic
User Defined Types (UDTs): Custom data structures with member definitions
Ladder Logic: RLL rungs with comments preserved
Structured Text: ST code blocks (when present)

Output Format

Each L5X file is exported to a subdirectory containing:

export/
├── Motor_Reversing/
│   ├── Motor_Reversing.aoi.sc      # Main AOI
│   ├── HMI_MotorControl.udt.sc     # Custom data type
│   ├── Error_Motor.udt.sc          # Error structure
│   └── HMIBitEnable.aoi.sc         # Dependency AOI
└── IO_DigitalInput/
    ├── IO_DigitalInput.aoi.sc
    └── HMI_DigitalInput.udt.sc

.sc File Structure

(* AOI: Motor_Reversing *)
(* Type: AddOnInstruction *)
(* Revision: 1.0 *)
(* Vendor: De Clerck Arnaud *)
(* Description: Controls a reversing motor contactor *)

(* PARAMETERS *)
VAR_INPUT
    tInTimeout: INT;  // Timeout time
    bInEstop: BOOL;   // Estop
END_VAR

VAR_OUTPUT
    bOutCommandForward: BOOL;  // Output for motor relay forward
    bOutError: BOOL;           // Motor Error Exists
END_VAR

(* LOCAL TAGS *)
VAR
    bTemp: BOOL;
    TON_TimeOut: TIMER;
END_VAR

(* IMPLEMENTATION *)
(* ROUTINE: Logic [RLL] *)

// Rung 0: Inputs
OTU(bTemp);

// Rung 1: Read HMI input buttons
[EQU(mode,2) OTE(bTemp) ,HMIBitEnable(...) ];

Benefits

Version Control: Track changes to PLC logic over time
Code Review: Review ladder logic in pull requests
Documentation: Self-documenting with comments preserved
Diffing: Use standard diff tools to compare versions
Search: Grep through PLC logic to find specific tags/instructions

Siemens TIA Portal / AX ST Parsing

The Siemens parser reads .st source files (Structured Text exported from TIA Portal or Siemens AX) and extracts them into the same internal data model used by the Rockwell pipeline, so the ontology analyzer works identically for both platforms.

What Gets Parsed

Classes (Function Blocks): CLASS ... END_CLASS with public/private variables and methods
Types (UDTs): TYPE ... STRUCT ... END_STRUCT END_TYPE with member definitions
Programs: PROGRAM ... END_PROGRAM with external references and inline logic
Configurations: CONFIGURATION ... END_CONFIGURATION with task assignments and VAR_GLOBAL I/O mappings (AT %IX / %QX addresses)
Methods: Extracted as routines with local variables and ST logic bodies
Namespaces: Used as grouping metadata

Variable Mapping

Siemens Construct	Internal Direction
`VAR_INPUT`	Input
`VAR_OUTPUT`	Output
`VAR_IN_OUT`, `VAR_EXTERNAL`, `VAR_GLOBAL`	InOut
`VAR PUBLIC` (in CLASS)	Output (externally visible)
`VAR PRIVATE` (in CLASS)	Local
`VAR` (in PROGRAM/METHOD)	Local

Example: Parsing a Siemens Project

# Parse and display all blocks
.\siemens-export.ps1 -Input ".\scripts\siemensprocessing\examplesiemens"

# Run ontology analysis (requires ANTHROPIC_API_KEY)
python scripts/ontology_analyzer.py ".\scripts\siemensprocessing\examplesiemens" --siemens -v

# Parse a single file directly
python scripts/siemens_parser.py "conveyorControl.st"

Multi-Block Files

A single .st file can contain multiple blocks (e.g., a TYPE and a CLASS). The parser extracts each as a separate entity for individual analysis, which mirrors how Rockwell exports each AOI/UDT as a separate .sc file.

Authoritative Import Behavior

The import is authoritative - the import directory is the source of truth:

POUs/GVLs not in import directory → DELETED from project
Methods not in import directory → DELETED from their POU
GVL content is fully replaced (variables not in file are removed)

Use --dry-run to preview deletions before applying!

Requirements

CODESYS V3.5 SP21 or later
Python 3.x
PowerShell 5.1+ (for driver scripts)
Windows (CODESYS is Windows-only)

Python Scripts (Direct Usage)

CODESYS

# Export from XML
python scripts/codesys_export_from_xml.py "Project.xml" "output_dir"

# Generate diff
python scripts/codesys_diff.py "dir1" "dir2" "diff_output"

# Apply diff
python scripts/codesys_apply.py "diff_dir" "target_dir" "project.project" "output_dir"

# Import (runs CODESYS headless)
python scripts/codesys_import_external.py "Project.project" "import_dir" --dry-run

Rockwell/Allen-Bradley

# Export L5X file
python scripts/l5x_export.py "Motor_Control.L5X" "output_dir"

# Export all L5X files in directory
python scripts/l5x_export.py "PLC" "output_dir"

Siemens TIA Portal / AX

# Parse a single ST file
python scripts/siemens_parser.py "conveyorControl.st"

# Parse all ST files in a directory
python scripts/siemens_parser.py "siemens_project/"

# Run ontology analysis on Siemens ST files
python scripts/ontology_analyzer.py "siemens_project/" --siemens -v

# Analyze a single Siemens file (auto-detected by .st extension)
python scripts/ontology_analyzer.py "conveyorControl.st" -v

Name		Name	Last commit message	Last commit date
Latest commit History 24 Commits
docs		docs
electron-ui		electron-ui
legacy		legacy
scripts		scripts
.gitignore		.gitignore
README.md		README.md
build-log.txt		build-log.txt
build.ps1		build.ps1
codesys-apply.ps1		codesys-apply.ps1
codesys-diff.ps1		codesys-diff.ps1
codesys-export.ps1		codesys-export.ps1
codesys-import.ps1		codesys-import.ps1
codesys-merge.ps1		codesys-merge.ps1
l5x-export.ps1		l5x-export.ps1
l5x-ontology.ps1		l5x-ontology.ps1
pyinstaller.spec		pyinstaller.spec
requirements.txt		requirements.txt
siemens-export.ps1		siemens-export.ps1

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