Modelica.StateGraph

Library of hierarchical state machine components to model discrete event and reactive systems

Information

Note, there is a much improved version of this library called "Modelica_StateGraph2". If this library is not yet distributed with your Modelica tool, you can download it from https://github.com/modelica/Modelica_StateGraph2. In the Users Guide a detailed comparison is given. It is highly recommended to use Modelica_StateGraph2 instead of Modelica.StateGraph.

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 JGrafchart method and takes advantage of Modelica features for the "action" language. JGrafchart 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 deficiencies of StateCharts.

For an introduction, have especially a look at:

StateGraph.UsersGuide discusses the most important aspects how to use this library.
StateGraph.Examples contains examples that demonstrate the usage of this library.

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 JGrafcharts, 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 JGrafcharts, Grafcet, Sequential Function Charts and StateCharts global variables are nearly always needed).

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name	Description
UsersGuide	User's Guide of StateGraph Library
Examples	Examples to demonstrate the usage of the components of the StateGraph library
Interfaces	Connectors and partial models
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
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
Alternative	Alternative splitting of execution path (use component between two steps)
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)

Name	Description
Fire condition
condition	= true, if transition may fire (time varying expression)
Custom Parameters
localCondition	= true, if transition may fire
Timer
enableTimer	= true, if timer is enabled
waitTime	Wait time before transition fires [s]

Connectors

Name	Description
inPort	Vector of transition input connectors
outPort	Vector of transition output connectors

Modelica.StateGraph.TransitionWithSignal

Transition where the fire condition is set by a Boolean input signal

Information

Extends from Interfaces.PartialTransition (Partial transition with input and output connections).

Parameters

Name	Description
Custom Parameters
localCondition	= true, if transition may fire
Timer
enableTimer	= true, if timer is enabled
waitTime	Wait time before transition fires [s]

Connectors

Name	Description
condition
inPort	Vector of transition input connectors
outPort	Vector of transition output connectors

Modelica.StateGraph.Alternative

Alternative splitting of execution path (use component between two steps)

Parameters

Name	Description
nBranches	Number of alternative branches

Connectors

Name	Description
inPort
outPort
join[nBranches]
split[nBranches]

Modelica.StateGraph.Parallel

Parallel splitting of execution path (use component between two transitions)

Parameters

Name	Description
nBranches	Number of parallel branches that are executed in parallel

Connectors

Name	Description
inPort
outPort
join[nBranches]
split[nBranches]

Modelica.StateGraph.PartialCompositeStep

Superclass of a subgraph, i.e., a composite step that has internally a StateGraph

Parameters

Name	Description
Exception connections
nSuspend	Number of suspend ports
nResume	Number of resume ports

Connectors

Name	Description
inPort
outPort
suspend[nSuspend]
resume[nResume]

Modelica.StateGraph.StateGraphRoot

Root of a StateGraph (has to be present on the highest level of a StateGraph)

Information

On the highest level of a StateGraph, an instance of StateGraphRoot has to be present.

The StateGraphRoot object is needed, since all Step objects have an "outer" reference to communicate with the "nearest" CompositeStep (which inherits from PartialCompositeStep), especially to abort a CompositeStep via the "suspend" port. Even if no "CompositeStep" is present, on highest level a corresponding "inner" definition is needed and is provided by the StateGraphRoot object.

Extends from StateGraph.Interfaces.CompositeStepState (Communication channel between CompositeSteps and steps in the CompositeStep).

Connectors

Name	Description
subgraphStatePort

Automatically generated Thu Oct 1 16:07:37 2020.