Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

23.3 STATE BASED MODELLING

 

· When we have a single sequence of modes we can use state diagrams.

 

· State diagrams divide a system behavior into discrete states.

 

· The basic technique uses states and transitions to model the systems.

 

 

· The most essential part of creating state diagrams is identifying states. Some key questions to ask are,

  1. 1. Consider the system,
    1. What does the system do normally?
    2. Does the system behavior change?
    3. Can something change how the system behaves?
    4. Is there a sequence to actions?
  2. 2. List `modes' of operation where the system is doing one identifiable activity that will start and stop. Keep in mind that some activities may just be to wait.

 

· Consider a coffee vending machine,

 

 

· These states can be organized into a state diagram and transitions can be added.

 

 

· Draw a state diagram for the problem below.

 

 

· Draw a state diagram for,

 

 

 

23.3.1 State Diagrams Example