fiobjects in Model Explorer
You can view and edit
fi objects and their
fimath properties using Model Explorer in Simulink®.
You can change the writable properties of
from the Model Explorer, but you cannot change the numeric type properties
fi objects after creation.
You can read fixed-point data from the MATLAB® workspace
into a Simulink model via the From
Workspace block. To do so, the data must be in a structure
format with a
fi object in the
In array format, the From Workspace block only accepts real, double-precision
To read in
fi data, the Interpolate
data parameter of the From Workspace block must not be
selected, and the Form output after final data value by parameter
must be set to anything other than
You can write fixed-point output from a model to the MATLAB workspace via the To Workspace block in either array or structure format. Fixed-point data written by a To Workspace block to the workspace in structure format can be read back into a Simulink model in structure format by a From Workspace block.
To write fixed-point data to the MATLAB workspace as a
select the Log fixed-point data as a fi object check
box on the To Workspace block dialog. Otherwise, fixed-point data
is converted to
double and written to the workspace
For example, you can use the following code to create a structure
in the MATLAB workspace with a
fi object in
values field. You can then use the From Workspace
block to bring the data into a Simulink model.
a = fi([sin(0:10)' sin(10:-1:0)']) a = 0 -0.5440 0.8415 0.4121 0.9093 0.9893 0.1411 0.6570 -0.7568 -0.2794 -0.9589 -0.9589 -0.2794 -0.7568 0.6570 0.1411 0.9893 0.9093 0.4121 0.8415 -0.5440 0 DataTypeMode: Fixed-point: binary point scaling Signedness: Signed WordLength: 16 FractionLength: 15 s.signals.values = a s = signals: [1x1 struct] s.signals.dimensions = 2 s = signals: [1x1 struct] s.time = [0:10]' s = signals: [1x1 struct] time: [11x1 double]
The From Workspace block in the following model has the
the Data parameter.
Remember, to write fixed-point data to the MATLAB workspace
fi object, select the Log fixed-point
data as a fi object check box on the To Workspace block
dialog. Otherwise, fixed-point data is converted to
written to the workspace as
In the model, the following parameters in the Solver pane of the Model Configuration Parameters dialog have the indicated settings:
Start time —
Stop time —
(no continuous states)
Fixed step size (fundamental sample time) —
The To Workspace block writes the result of the simulation to
the MATLAB workspace as a
simout.signals.values ans = 0 -8.7041 13.4634 6.5938 14.5488 15.8296 2.2578 10.5117 -12.1089 -4.4707 -15.3428 -15.3428 -4.4707 -12.1089 10.5117 2.2578 15.8296 14.5488 6.5938 13.4634 -8.7041 0 DataTypeMode: Fixed-point: binary point scaling Signedness: Signed WordLength: 32 FractionLength: 25
You can use Fixed-Point Designer™ expressions to specify the value and data type of block parameters in Simulink. For more information, see Specify Fixed-Point Data Types (Simulink).
When fixed-point signals are logged to the MATLAB workspace
via signal logging, they are always logged as
To enable signal logging for a signal:
Select the signal.
Open the Record dropdown.
Select Log/Unlog Selected Signals.
For more information, refer to Export Signal Data Using Signal Logging (Simulink).
When you log signals from a referenced model or Stateflow® chart in your model, the
word lengths of
fi objects may be larger than you
expect. The word lengths of fixed-point signals in referenced models
and Stateflow charts are logged as the next largest data storage
Simulink provides an application program interface (API)
that enables programmatic access to block data, such as block inputs
and outputs, parameters, states, and work vectors, while a simulation
is running. You can use this interface to develop MATLAB programs
capable of accessing block data while a simulation is running or to
access the data from the MATLAB command line. Fixed-point signal
information is returned to you via this API as
For more information on the API, refer to “Accessing Block
Data During Simulation” in the Simulink documentation.