NXOpen Python Tutorials

A collection of NXOpen Python tutorials for automating Siemens NX CAD/CAM/CAE software.

Introduction

NXOpen is an Application Programming Interface (API) that gives users access to the Siemens NX/Simcenter 3D model and tool commands, allowing customization and extension of the baseline software capabilities. Applications include:

Creation and manipulation of part geometry and/or drawings
Data importing or parsing of model geometry information and analysis results
Automation of repetitive CAD/CAM/CAE tasks
Custom feature creation and batch processing

NXOpen can be used with multiple programming languages including C#, C++, Java, Python, and Visual Basic. This repository focuses on Python examples.

Getting Started

First Steps: Configuring NX for Python

To start with NX Python programming, you need to prepare your NX settings.

Step 1: Find or activate the Developer tab at the top NX ribbon:

Fig. 1 - Find or activate the Developer tab.

If the tab does not exist already, right-click on the top ribbon and find the Developer tab to activate it.

Step 2: Change the macro recording language from Visual Basic to Python.

One great way to develop or learn NX Python programming is to record macros while using the GUI. By default, NX saves macros in Visual Basic. To change that to Python, go to File > Preferences > User Interface:

Fig. 2 - Go to the User Interface Preference panel.

Or press Ctrl + 2 keyboard shortcut. Then in the User Interface Preferences dialog, change the Journal Language to Python:

Fig. 3 - Change the Journal Language to Python.

Tutorials

Example 1: Hello World! (Message Box)

Let's start with a very simple "Hello World!" example where a message window will show a text message.

# ex0001.py
import NXOpen.UF

def main(): 
    NXOpen.UF.UFSession.GetUFSession().Ui.DisplayMessage("Hello World!", 1)

if __name__ == '__main__':
    main()

Running the code:

Go to the Developer tab and find the Play button:

Fig. 4 - Find the Play button.

In the Journal Manager panel, click Browse to find and run the code:

Fig. 5 - The Journal Manager panel.

The result will be:

Fig. 6 - Message box window.

Example 2: Hello World! (Listing Window)

The message box window is good for alerting users of specific issues. However, the text is not searchable or selectable. Alternatively, we can use the Listing Window:

# ex0002.py
import NXOpen

def main(): 
    listing_window = NXOpen.Session.GetSession().ListingWindow
    
    listing_window.Open()
    listing_window.WriteFullline("Hello world!")
    listing_window.Close()

if __name__ == '__main__':
    main()

The result:

Fig. 7 - Information/Listing window.

Example 3: Creating a Cylinder Feature

This example demonstrates how to create 3D geometry programmatically using the CylinderBuilder:

# ex0003.py
import NXOpen
import NXOpen.Features

def cylinder_builder(session=NXOpen.Session.GetSession(), 
                     work_part=NXOpen.Session.GetSession().Parts.Work, 
                     height=100, 
                     diameter=50):
    mark_id = session.SetUndoMark(NXOpen.Session.MarkVisibility.Visible, "Cylinder")
    cylinder = work_part.Features.CreateCylinderBuilder(NXOpen.Features.Feature.Null)
    cylinder.Diameter.SetFormula(str(diameter))
    cylinder.Height.SetFormula(str(height))
    nx_object = cylinder.Commit()
    return nx_object, mark_id

def main():
    cylinder_builder(height=40, diameter=100)

if __name__ == '__main__':
    main()

This creates a cylinder with the specified height and diameter that you can edit manually from the model history or update programmatically.

Repository Structure

NXOpen_Python_tutorials/
├── Examples/
│   ├── ex0001.py    # Message box "Hello World"
│   ├── ex0002.py    # Listing window output
│   └── ex0003.py    # Cylinder feature creation
├── Pictures/        # Screenshots for documentation
├── .gitignore
├── LICENSE          # CC0-1.0 Public Domain
└── README.md

Repository History

This repository was created in August 2021 and has evolved through contributions focused on educational content for NX automation.

gitGraph
   commit id: "init" tag: "v0.1"
   commit id: "gitignore"
   commit id: "license"
   commit id: "first-steps"
   commit id: "ex0001"
   commit id: "ex0002"
   commit id: "ex0003"
   commit id: "typo-fix"
   branch contributor
   checkout contributor
   commit id: "png-lowercase"
   commit id: "readme-paths"
   checkout main
   merge contributor id: "PR#3"
   commit id: "grammar-fixes" tag: "current"

Timeline

August 2021: Foundation

Initial commit with .gitignore and CC0 license
Added "First Steps" guide for NX Python setup
Created examples ex0001.py, ex0002.py, and ex0003.py
Fixed variable name typo (xn_object → nx_object)

January–February 2022: Standardization

File extension standardization (.PNG → .png) by contributor @j-eggi
README path updates for cross-platform compatibility
Merged Pull Request #3

September 2022: Polish

Grammar and capitalization fixes
Improved documentation clarity and formatting

Resources

Official Documentation

Community Resources

NX Journaling Forum - Community Q&A for NX automation
Siemens Community - Official Siemens support forums

Related Articles

What Is NX Open? (Explained with examples)
Automating Load Case Combination in Simcenter 3D using NXOpen + Python

Contributing

Contributions are welcome! If you have NXOpen Python examples you'd like to share:

Fork this repository
Create a new branch for your feature
Add your example to the Examples/ folder
Update the README with documentation
Submit a Pull Request

Support This Project

If you find these tutorials helpful, please consider:

License

This work is dedicated to the public domain under CC0 1.0 Universal. You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission.

Author

Dr. Foad Sojoodi Farimani

GitHub: @Foadsf
Stack Overflow: Foad S. Farimani
Twitter: @fsfarimani
LinkedIn: fsfarimani