Read data from workspace

Sources

The From Workspace block reads data from a workspace and outputs the data as a signal.

The From Workspace icon displays the expression specified in
the **Data** parameter. For details about how Simulink^{®} software
evaluates this expression, see Symbol Resolution.

In the **Data** parameter of the block, enter
a MATLAB^{®} expression that specifies the workspace data. The expression
must evaluate to one of the following:

A MATLAB

`timeseries`

objectA structure of MATLAB

`timeseries`

objectsAn array or structure containing an array of simulation times and corresponding signal values

The format of a MATLAB `timeseries`

object,
array, or structure loaded (imported) by a From Workspace block is
the same as that used to load root-level input port data from the
workspace.

To load any non-bus data from the workspace, use a MATLAB

`timeseries`

object or a structure with time. For guidelines on choosing time vectors for discrete systems, see Techniques for Importing Signal Data.To load bus data, use a structure of MATLAB

`timeseries`

objects. For details, see Import Structures of timeseries Objects for Buses.

You can use the From Workspace block to load MATLAB `timeseries`

object
data that was saved by a To File block, without making any changes
to the data.

To use the From Workspace block to load `Array`

format
data, transpose the array data before the From Workspace block loads
the data that a To File block saved. The data saved by the To File
block contains columns with consecutive time stamps, followed by the
corresponding data. The transposed data contains rows with consecutive
time stamps, followed by the corresponding data. To provide the required
format, use MATLAB `load`

and `transpose`

commands with
the MAT-file (see Reshaping a Matrix). To avoid having to transpose
the data again later, resave the transposed data for future use.

To use the From Workspace block to load data exported by a To Workspace block in a previous simulation
for use in a later simulation, save the To Workspace block data in
either `Timeseries`

or ```
Structure
with Time
```

format. For details, see Techniques for Importing Signal Data.

You can use a To Workspace block (with `Structure`

or ```
Structure
With Time
```

format) or a root Outport block to log variable-size
signals. You can then use the To Workspace variable with the From
Workspace block.

Alternatively, you can create a MATLAB structure to contain
variable-size signal data. For each `values`

field
in the structure, include a `valueDimensions`

field
that specifies the run-time dimensions for the signal. For details,
see Simulink Models Using Variable-Size Signals.

If you select the **Interpolate data** option,
the block uses linear Lagrangian interpolation to compute data values
for time hits that occur between time hits for which the workspace
supplies data.

For variable-size signals, clear **Interpolate data**.

Combine the settings of the **Form output
after final data value by** and **Interpolate
data** parameters to determine the block output after the
last time hit for which workspace data is available. For details,
see the **Form output after final data value by** parameter.

The **Enable zero-crossing detection** parameter
applies only if the sample time is continuous (`0`

).

If you select the **Enable zero-crossing detection** parameter,
and if the input array contains more than one entry for the same time
hit, Simulink detects a zero crossing at that time hit.

For bus signals, Simulink detects zero crossings across all leaf bus elements.

The From Workspace block accepts data from the workspace and outputs real or complex signals of any type supported by Simulink, including fixed-point and enumerated data types.

The From Workspace block also accepts a bus object as a data
type. To load bus data, use a structure of MATLAB `timeseries`

objects.
For details, see Import Structures of timeseries
Objects for Buses.

Real signals of type `double`

can be in any
format that the From Workspace block supports. For complex signals
and real signals of a data type other than `double`

,
use any format except `Array`

.

A MATLAB expression that evaluates to one of the following:

A MATLAB timeseries object

A structure of MATLAB timeseries objects

To load bus data, use a structure of MATLAB timeseries objects. For details, see Import Structures of timeseries Objects for Buses.

A two-dimensional matrix:

The first element of each matrix row is a time stamp.

The rest of each row is a scalar or vector of signal values.

A structure, with or without time, which contains:

A

`signals.values`

field, which contains a vector of signal valuesAn optional

`signals.dimensions`

array, which contains the dimensions of the signalAn optional

`time`

vector, which contains time stampsIf you do not specify a time vector:

Set

**Sample time (-1 for inherited)**to a value other than`0`

(continuous).Clear

**Interpolate data**.Set

**Form output after final data value by**to a value other than`Extrapolate`

.

The

`n`

'th`time`

element is the time stamp of the`n`

'th`signals.values`

element. For details, see Techniques for Importing Signal Data.

For example, suppose that the workspace contains a column vector
of times named `T`

and a column vector of corresponding
signal values named `U`

. Entering the expression ```
[T
U]
```

for this parameter yields the required input array. If
the required array or structure already exists in the workspace, enter
the name of the structure or matrix in this field.

The required data type for the data for the workspace variable
that the From Workspace block loads. For non-bus types, you can use ```
Inherit:
auto
```

to skip any data type verification. For more information,
see Specify Block Output Data Types.

To load bus data, use a structure of MATLAB timeseries objects. For details, see Import Structures of timeseries Objects for Buses.

`Inherit: auto`

— Default.`double`

`single`

`int8`

`uint8`

`int16`

`uint16`

`int32`

`uint32`

`boolean`

`fixdt(1,16,0)`

— Data type is fixed-point (1,16,0).`fixdt(1,16,2^0,0)`

— Data type is fixed-point (1,16,2^0,0).`Enum: <class_name>`

— Data type is enumerated, for example,`Enum: Basic Colors`

.`Bus: <bus_object>`

— Data type is a bus object.`<data type expression>`

— The name of a data type object, for example`Simulink.NumericType`

. Do not specify a bus object as the expression.

Displays the **Data Type Assistant**, to help
you to set the **Output data type** parameter.

The category of data to specify. For more information, see Specify Block Output Data Types.

`Inherit`

— Inheritance rule for data types. Selecting`Inherit`

enables a second menu/text box to the right. (Default)`Built in`

— Built-in data types. Selecting`Built in`

enables a second menu/text box to the right. Select one of the following choices:`double`

— Default`single`

`int8`

`uint8`

`int16`

`uint16`

`int32`

`uint32`

`boolean`

`Fixed point`

— Fixed-point data types`Enumerated`

— Enumerated data types. Selecting`Enumerated`

enables a second menu/text box to the right, where you can enter the class name.`Bus`

— Bus object. Selecting`Bus`

enables a**Bus object**parameter to the right, where you enter the name of a bus object that you want to use to define the structure of the bus. If you need to create or change a bus object, click**Edit**(to the right of the**Bus object**field) to open the Simulink Bus Editor. For details, see Manage Bus Objects with the Bus Editor.`Expression`

— Expression that evaluates to a data type. Selecting`Expression`

enables a second menu/text box to the right, where you enter the expression. Do not specify a bus object as the expression.

Sample rate of loaded data. For details, see Specify Sample Time.

Select this option to have the block linearly interpolate at time hits for which no corresponding workspace data exists. Otherwise, the current output equals the output at the most recent time for which data exists.

The From Workspace block interpolates using the two corresponding workspace samples:

For

`double`

data, linearly interpolates the value using the two corresponding samplesFor

`Boolean`

data, uses`false`

for the first half of the time between two time stamps and`true`

for the second halfFor a built-in data type other than

`double`

or`Boolean`

, upcasts the data to`double`

, performs linear interpolation (as described above for`double`

data), and then downcasts the interpolated value to the original data type

You cannot use linear interpolation with enumerated (`enum`

)
data.

The block uses the value of the last known data point as the value of time hits that occur after the last known data point.

Combine the settings of the **Interpolate
data** and **Form output after final
data value by** parameters to determine the block output
after the last time hitfor which workspace data is available. For
details, see the **Form output after final data
value by** parameter.

If you select the **Enable zero-crossing detection** parameter,
then when the input array contains more than one entry for the same
time hit, Simulink detects a zero crossing at that time. For
example, suppose the input array has this data:

time: 0 1 2 2 3 signal: 2 3 4 5 6

At time 2, there is a zero crossing from input signal discontinuity. For more information, see Zero-Crossing Detection.

For bus signals, Simulink detects zero crossings across all leaf bus elements.

Combine the settings of the **Form output
after final data value by** and **Interpolate
data** parameters to determine the block output after the
last time hit for which workspace data is available. The following
table describes the block output based on the values of the two options:

Setting for Form Output After Final Data Value By | Setting for Interpolate Data | Block Output After Final Data |
---|---|---|

| On | Extrapolated from final data value |

Off | Error | |

| On | Zero |

Off | Zero | |

| On | Final value from workspace |

Off | Final value from workspace | |

| On | Error |

Off | Repeated from workspace if the workspace data is in structure-without-time format. Error otherwise. |

For example, if **Form output after final
data value by** is `Extrapolation`

and **Interpolate data** is selected, the block uses
the last two known data points to extrapolate data points that occur
after the last known point. Consider the following model.

In this model, the From Workspace block reads data from the workspace consisting of the output of the Simulink Sine block sampled at one-second intervals. The workspace contains the first 16 samples of the output. The top and bottom X-Y plots display the output of the Sine Wave and From Workspace blocks, respectively, from 0 to 20 seconds. The straight line in the output of the From Workspace block reflects the block's linear extrapolation of missing data points at the end of the simulation.

The From Workspace block allows you to read 1-D and 2-D signals into Simulink. The From Workspace block does not read n-D signals into Simulink.

Create two signals `x`

and `y`

with
a time vector `t`

, and then import the values into Simulink with
an array.

In the MATLAB Command Window, enter

t = [0:0.2:10]'; x = sin(t); y = 10*sin(t);

The time vector must be a column vector.

Add a From Workspace block to your model.

Double-click the block to open the block parameters dialog. In the

**Data**field, enter the array [t,x,y],

Create two signals `x`

and `y`

with
a time vector `t`

, and then import the values into
Simulink with a structure.

In the MATLAB Command Window, enter

t = [0:0.2:10]'; x = sin(t); y = 10*sin(t); wave.time = t; wave.signals.values = [x,y]; wave.signals.dimensions =2;

The time vector must be a column vector. The

`signals.dimensions`

field for the signal is a scalar corresponding to number of columns in the`signals.values`

field.Add a From Workspace block to your model.

Double-click the block to open the block parameters dialog. In the

**Data**field, enter the structure name.

If you do not have a time vector, you can define the sample time in your model.

In the MATLAB Command Window, enter

wave.time = [];

Double-click the From Workspace block to open the block parameters dialog. In the

**Sample time**field, enter a time interval. For example, enter`0.2`

. Clear the**Interpolate data**check box. From the**Form output after final data value by**, select either`Setting to zero`

,`Holding final value`

, or`Cyclic repetition`

. Do not select`Extrapolation`

.

To load 2-D signals from the MATLAB workspace into Simulink,
you must have the signals in a structure format. This example creates
a 10–by–10 matrix (2-D signal) using the `magic`

function,
and then creates a 3-D matrix by adding a time vector.

In the MATLAB Command Window, enter

t1 = [0:0.2:10]'; m = magic(10); M = repmat(m,[1 1 length(t1)]); data.time=t1; data.signals.values = M; data.signals.dimensions=[10 10];

The time vector must be a column vector. The

`signals.values field`

is a 3-D matrix where the third dimension corresponds to time. The`signals.dimensions`

field is a two element vector where the first element is the number of rows and the second element is the number of columns in the`signals.values`

field.Double-click the From Workspace block to open the block parameters dialog. In the

**Data**field, enter the name of the structure.

Sample Time | Specified in the |

Scalar Expansion | No |

Dimensionalized | Yes |

Multidimensionalized | Yes |

Zero-Crossing Detection | Yes, if enabled. |

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