Install Python

Download & Install Python from

Please install python Version >=3.5.


Moddy does not support Python 2.x.

During install, click checkbox add python to PATH

Tested with python 3.5, 3.6 and 3.7 under Windows 10.

Installing GraphViz

Install GraphViz from

Then ensure that the bin/ subdirectory of the GraphViz installation is in your PATH.

Install Moddy

$ pip install -U moddy

Test Moddy

Copy the text from this Basic Demo and save it to into an arbitrary directory on your machine.

Then try to run the demo:

$ python

Demo output

The console log should end with

TRC:      11.8s STA     Bob(Part) //
TRC:      11.8s >MSG    Bob.mouth(OutPort) //  req=11.8s beg=11.8s end=12.8s dur=1.0s msg=[Hm?]
SIM: Stops because stop_time reached
SIM: Simulator stopped at 12.0s. Executed 9 events in 0.000 seconds
saved sequence diagram in output/1_hello.html as iaViewer
Saved structure graph to output/1_hello_structure.svg
saved output/1_hello.csv as CSV

You should also find a folder output in your directory that contains the result files:


Open 1_hello.html into a web browser and it should look like this The sequence diagram

Using Moddy with Eclipse


This step is optional, you can use Moddy also without Eclipse. I just put it here because I personally use Eclipse.

Installing Eclipse

Download & Install Eclipse from

Installing PyDev

In Eclipse, select Help->Install new Software and enter for both Name and location


Create a Moddy Project

In Eclipse Select New --> Project --> PyDev Project:


Name the project myFirstModdyProject:


Create a module named


Copy the text from this Basic Demo and paste it into

Now you can Run the You should get an output as described in Demo output.