Getting Started with the Python language

The Ansys Motion Standalone Preprocessor C# library can be used in the python code by using Python.NET or IronPython.

System requirements

If you are using CPython, you will need to install Python.NET first.

pip install pythonnet

It's a good idea to add the Motion\bin directory to your PATH environment variable. You can do this in the Python code as follows:

import sys
sys.path.append('Ansys installed path/Motion/bin')

The API class

The Ansys Motion Standalone Preprocessor C# library supports the headless application interface. The API class allows you to use it.

import clr
clr.AddReference("dfpreAPI")
from VM.Managed.DAFUL.Pre import Api

app = Api.Start()
# Enter your code here.
app.Dispose()

The Session Class

All operations of the Ansys Motion Standalone Preprocessor must be called within the Session in the following way:

import clr
clr.AddReference("dfpreAPI")
from VM.Managed.DAFUL.Pre import Api

app = Api.Start()
session = app.UseSession("Session name")
# Enter your code here.
session.Dispose()
app.Dispose()

Disable History

It is highly recommended to disable the History Manager when using the headless application interface.

import clr
clr.AddReference("VMHist")
from VM.Managed.History import HistoryManager

HistoryManager.UseHistoryManager = False

Example

The following sample code illustrates how to create and analyze a simple free-fall model:

# Please ensure that the 'Motion/bin' directory is registered in the PATH environment variable before running this script.
# If doing so in this code, uncomment the following two lines and set the exact location of the Motion installation as your configuration.
# import sys
# sys.path.append('Ansys installed path/Motion/bin')

# Using Pythoh.NET
import clr

# Adding references from Ansys Motion Standalone Preprocessor
clr.AddReference("dfpreAPI")
clr.AddReference("VM")
clr.AddReference("VM.API.Pre")
clr.AddReference("VM.Models.Pre")
clr.AddReference("VMHist")

# Import the appropriate classes from the Ansys Motion Standalone Preprocessor C# library.
from VM import Vector
from VM.API.Pre import SolidBodyAPI, SimulationAPI
from VM.Managed.DAFUL.Pre import Api
from VM.Managed.History import HistoryManager
from VM.Models.Pre import ExpressionValueVariable as ExpVar

# Start the headless application interface
app = Api.Start()

# Disable History Manager
HistoryManager.UseHistoryManager = False

# Start a session to run custom Python code.
session = app.UseSession("Session name")

# Create new subsystem file
doc = app.CreateDocument("free_fall.dfsub")

# Create a solid sphere in the inertial reference frame with a radius of 10.0.
sphere = SolidBodyAPI.CreateSolidSphere(doc, Vector(0, 0, 10), ExpVar(10))

# Running the Solver
SimulationAPI.RunSimulation(doc)

# Save the new subsystem file
app.SaveFile(doc)

# Close session
session.Dispose()

# Shutdown headless application interface
app.Dispose()

Motion Standalone Preprocessor C# library 2026 R1