Extract Subsystems for Analysis
Overview of Subsystem Extraction
If you have a large model that slows down your analysis or has unreachable objectives, you may want to analyze atomic subsystems or Stateflow® atomic subcharts using Simulink® Design Verifier™. This technique allows you to implement a bottom-up approach to analyzing a large model, as described in Bottom-Up Approach to Model Analysis.
When you analyze a subsystem or atomic subchart, the software:
Extracts the subsystem or subchart into a new model.
If required, adds blocks to the newly created model that replicate the execution context of the subsystem or subchart within its parent model.
Analyzes the extracted model and produces results.
allows you to extract subsystems and atomic subcharts for component
verification. By extracting the subsystem or atomic subchart, you
can verify the component in isolation from the rest of the system,
allowing you to test the component algorithm. For more information,
see What Is Component Verification? and Functions for Component Verification.
Structure of the Extracted Model
When you analyze a subsystem or atomic subchart, Simulink Design Verifier creates a new model that contains the subsystem or atomic subchart, and any input and output ports that correspond to the ports connected to the original subsystem.
The software assigns the following properties to the ports in the new model, as determined by compiling the original model:
Minimum and maximum values of the signal ranges
The software names the new model
subsystem_name is the name of the
The next sections provide examples of how Simulink Design Verifier extracts and analyzes subsystems.
Analyze Subsystems That Read from Global Data Storage
A data store is a repository to which you can write data, and from which you can read data, without having to connect an input or output signal directly to the data store.
You create a data store using a Data Store Memory block or a
Simulink.Signal object. The
Data Store Memory block or
object represents the data store and specifies its properties. Every data store must
have a unique name.
When you analyze a subsystem that reads data from a data store that is accessed outside the subsystem, the analysis:
Adds a Data Store Memory block to the new model.
Adds an input port that writes to the data store. Since the input writes to the data store, the data can have any values (within the specified data type) for the purpose of the Simulink Design Verifier analysis.
If the data store specifies minimum and maximum values, those values are assigned to the new input port.
The following example analyzes a subsystem in the
This model defines a data store A, from which the atomic subsystem Reader reads data using a Data Store Read block.
Right-click the Reader subsystem and select Design Verifier > Generate Tests for Subsystem.
The Simulink Design Verifier log window shows that the software extracts the subsystem into a new model named
Reader, analyzes the extracted model, and offers you the choice of which results to produce.
Open the new
Readermodel that the software created in
The new Inport block A writes into the data store, which is used by the subsystem Reader in the new model.
Analyze Function-Call Subsystems
A function-call subsystem is a triggered subsystem whose execution is determined by logic internal to a C MEX S-function instead of by the value of a signal. Function-call subsystems are always atomic.
For more information, see Implement Function-Call Subsystems with S-Functions.
When you analyze a model with a function-call subsystem, Simulink Design Verifier creates a new model with an Inport block that mimics the trigger and a copy of the subsystem. The software then analyzes the new model.
The following example analyzes a function-call subsystem in
This model contains a Stateflow chart named Chart that triggers the function-call subsystem f.
Right-click the f subsystem and select Design Verifier > Generate Tests for Subsystem.
The software extracts the subsystem into a new model named
f0, analyzes the extracted model, and produces results.
f0model that the software created in
The Inport block and the new subsystem block mimic the trigger for the function-call subsystem f in the new
Analyze Global Simulink Function
A Simulink function is a computational unit that calculates a set of outputs when provided with a set of inputs.
When you analyze Simulink Function
Design Verifier creates a new model containing a MATLAB function block
_SldvExportFcnScheduler and a copy of the subsystem. This
MATLAB function block invokes Simulink Functions aperiodically and is driven by inports which
represent the input arguments of the Simulink Function. An additional Inport block called
FcnTriggerPort, the value of which indicates whether to
invoke a particular function in a time step or not.
The following example analyzes a global Simulink function in the
Right-click the subsystem and select Design Verifier > Generate Tests for Subsystem.
The software extracts the subsystem into a new model and analyzes the extracted model, and produces results.
Open the new model
SimulinkFunctionRunnable0that the software creates in
The Inport block
FcnTriggerPort, invokes the Simulink Function
SimulinkFunctionRunnablein the new