NX Open (API)
Siemens' multi-language API for NX customisation — C++, .NET, Java, Python.
Definition
NX Open provides full-feature API access: open files, create features, query geometry, customise UI, drive automation. Available in C++, .NET (C#, VB), Java, Python (via Open Python). Knowledge Fusion (KF) is a proprietary rule-based language for parametric design automation. Legacy UFUN (User Function) API is C-only and pre-dates NX Open.
Why it matters
Enterprises with deep NX customisation needs (CAD-PLM bridges, design rule enforcement, custom workbenches) build on NX Open. Python is the lowest-effort starting point; C++ and .NET deliver the deepest integration.
Technical Deep Dive & Core Mechanics
In 2D vector engines like Siemens NX, NX Open (API) directly influences the system's memory-mapped database structure. Rather than storing arbitrary pixel rasters, the DWG/DXF format describes each entity using grouped DXF codes (such as code 10 for coordinates, code 8 for layers, and code 100 for class markers). The virtual screen index utilizes highly optimized spatial indexing trees (like quad-trees or R-trees) to manage viewport pan and zoom sweeps efficiently.
Cross-Discipline Collaboration & Handoff
In global multi-office projects, NX Open (API) is a high-frequency handoff node between diverse software packages. During cross-platform export (for example, exporting Siemens NX drawings to IFC for coordination in Navisworks or Solibri, or converting mechanical STEP files into BIM detail families):
Common pitfalls
- Mixing multiple NX Open languages on the same project — maintenance overhead.
- NX Open code without version pinning — every NX release requires testing.
- Knowledge Fusion when NX Open Python would be more maintainable.
This concept is a core structural element of the Siemens NX drafting and engineering environment developed by Siemens Digital Industries Software. Siemens' high-end CAD/CAM/CAE platform — synchronous + parametric hybrid modelling, strong CAM, and Teamcenter PLM integration.
Relevant Siemens NX FAQs
❓ What is the difference between NX and UG?
Same product, different name. UG (UniGraphics) is the legacy name from 1973 until 2002, when Siemens (then EDS) rebranded to NX. Veteran users still say 'UG.' The .prt file format is continuous across the rename — UG files can open in modern NX.
❓ Can NX open SOLIDWORKS files?
❓ What is Knowledge Fusion?
NX's proprietary rule-based language for parametric design automation — pre-dates the modern NX Open API. KF rules capture engineering knowledge inside NX parts (e.g., 'if material is steel, use this fastener'). Modern projects often use NX Open Python or .NET instead, but KF still ships and is in active use in legacy enterprise customisations.
⚡ Concept Self-Test
🎓 Recommended Practice Lessons
Step-by-step practical exercises and certification-aligned paths chosen by our editors to master this concept:
Siemens NX Professional Design & Engineering Specialization
The Complete Siemens NX 2026 Masterclass: From Beginner to Pro
Siemens NX Certified Associate Exam Study Guide & Mock Practice
🌳 Semantic Crossroads & Navigation Pathways
Trunk-Branch-Leaf ModelCore glossary, interactive graph, and domain-wide concept index.
Parent design environments and platforms implementing this method natively.