 | Examples
Examples to demonstrate the usage of the components of the StateGraph library |
 | Interfaces
Connectors and partial models |
 | Temporary
Components that will be provided by other libraries in the future |
 | UsersGuide
User's Guide of StateGraph Library |
 | Alternative
Alternative splitting of execution path (use component between two steps) |
 | InitialStep
Initial step (= step that is active when simulation starts) |
 | InitialStepWithSignal
Initial step (= step that is active when simulation starts). Connector 'active' is true when the step is active |
 | Parallel
Parallel splitting of execution path (use component between two transitions) |
 | PartialCompositeStep
Superclass of a subgraph, i.e., a composite step that has internally a StateGraph |
 | StateGraphRoot
Root of a StateGraph (has to be present on the highest level of a StateGraph) |
 | Step
Ordinary step (= step that is not active when simulation starts) |
 | StepWithSignal
Ordinary step (= step that is not active when simulation starts). Connector 'active' is true when the step is active |
 | Transition
Transition where the fire condition is set by a modification of variable condition |
 | TransitionWithSignal
Transition where the fire condition is set by a Boolean input signal |
Library StateGraph is a free Modelica package providing
components to model discrete event and reactive
systems in a convenient
way. It is based on the JGraphChart method and
takes advantage of Modelica features for
the "action" language. JGraphChart is a further development of
Grafcet to include elements of StateCharts that are not present
in Grafcet/Sequential Function Charts. Therefore, the StateGraph
library has a similar modeling power as StateCharts but avoids
some deficiences of StateCharts.
For an introduction, have especially a look at:
A typical model generated with this library is shown
in the next figure where on the left hand side a two-tank
system with a tank controller and on the right hand side the
top-level part of the tank controller as a StateGraph is shown:
The unique feature of the StateGraph library with respect to JGraphCharts,
Grafcet, Sequential Function Charts, and StateCharts, is Modelica's
"single assignment rule" that requires that every variable is defined
by exactly one equation. This leads to a different "action" definition
as in these formalisms. The advantage is that the translator can either
determine a useful evaluation sequence by equation sorting or
reports an error if this is not possible, e.g., because a model
would lead to a non-determinism or to a dead-lock. As a side effect,
this leads also to simpler and more easier to understand models and
global variables are no longer needed (whereas in JGraphCharts,
Grafcet, Sequential Function Charts and StateCharts global variables
are nearly always needed).
The StateGraph library is currently available in a beta release.
The available components will most likely not be changed for the
release version. It is planned to improve the convenience of
building models with the StateGraph library for the release version
(this may require to introduce some additional annotations).
It is planned to include the StateGraph library in the
Modelica standard library.
It is most useful to combine this libray with the Modelica libraries
- Modelica.Blocks.Logical that provides
components available in PLCs (programmable logic controllers).
- UserInteraction that provides components to
interactively communicate with models in a running simulation.
Copyright © 1998-2009, Modelica Association and DLR
This Modelica package is free software; it can be redistributed and/or modified
under the terms of the Modelica license, see the license conditions
and the accompanying disclaimer
here.
