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State Tree Structure Simulator

General Info

The STS simulator can be used to validate and visualize the (events based) behaviour of STS models and the control functions generated with Ma/Wonham’s experimental sts tool (for more info on the use of this tool please check NBC help file) . With this simulator the user can step through STS models (event by event) and check what the result of designed requirements and generated control functions is on the behaviour of the STS model.


This program uses the python version of wxWidgets to build its GUI. In order to run this program correctly you need to install the wxPython package in you local python directory. The installation files for this package can be found here.

The simulator cannot be used for general STS models as defined by Ma/Wonham. For more info on the restrictions please check the help file or help menu item. Also, the python STS parser is somewhat more restrictive that the NBC program, for more info please check the sts_template.txt file in the zip file.

State Tree Structure info

For a short introduction to STS and the sythesis of control functions using STS please check this file

File info

  • - Main python code containing the GUI and internal visualization functions.
  • - Python code containing the python classes of State Trees (ST), Holons (HOLON) and BDD's (BDD). The code also includes the functions for loading and saving STS files from python and the functions needed to step through the model and calulate the set of eligible and valid events at a predefined state whitin the model.
  • sts_template.txt - The style file for saving your STS models. When not using this template the buildin STS parser will not be able load your STS model and generate an error.
  • stsSim_help.txt - Help file explaining all functions and menu items of the program.
  • Example directory - Directory containing an example STS file and simulation window (
  • - Python code used to generate Example

Screen capture

For a screen capture of the program please click screen_cap.jpg


STS simulator v3.01

The STS simulator v3.01 in Python

STS simulator v3.02

This version can also handle AND superstates that are in layers under the root-state.

Also a program is made which can check if a STS is well-formed (, an explanation file is added (checkWF_help.txt).

The STS simulator v3.02 in Python

IMPORTANT NOTE: If you already have created a canvas and you want to use this canvas in the STS simulator v3.02 you must change the following line from pySTS_v4 import * into from pySTS_v5 import *. Otherwise the file will not be able to load correct and errors will occur.

wonham/state_tree_structure_simulator.txt · Last modified: Thursday, 04 October 2007 : 08:32:28 (external edit)