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From Workspace

Load signal data from workspace into Simulink model

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  • From Workspace block

Libraries:
Simulink / Sources

Description

The From Workspace block reads data into a Simulink® model from a workspace and provides the data as a signal or a nonvirtual bus at the block's output. You can load data from the base workspace, model workspace, or mask workspace. You can use the From Workspace block to load signal data into any model or subsystem in a model hierarchy from a workspace accessible to the referenced model or subsystem.

You can specify how the block constructs the output from the workspace data, including the output sample period, interpolation and extrapolation behavior, and whether to use zero-crossing detection.

The From Workspace block icon shows the value of the Data parameter. For example, if you use the From Workspace block to load data in the variable x, you specify x as the value for the Data parameter, and the block displays x.

Specify Data to Load

Specify data for the From Workspace block to load using the Data parameter. You can specify the value of the Data parameter as a MATLAB® expression, such as a variable name. The expression in the Data parameter must evaluate to data in a format that the From Workspace block supports. For details about how the expression is evaluated, see Symbol Resolution.

The From Workspace block does not load data from a data dictionary. Use a data dictionary to store only design data for a model, not simulation input data. You can store design data related to the From Workspace block, such as the value for the Sample time parameter, in a data dictionary.

Examples

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Open Model

This example shows how to read a 2-D structure from the MATLAB workspace. When you open the model, the following code is executed by a PreLoadFcn callback:

t1 = 0.2 * [0:49]';
m = magic(10);
M = repmat(m,[1 1 length(t1)]);
data.time=t1;
data.signals.values = M;
data.signals.dimensions=[10 10];

This code creates 10-by-10 matrix (2-D signal) by using the magic function, and then creates a 3-D matrix by adding a time vector. 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. The first element is the number of rows and the second element is the number of columns in the signals.values field.

When you run the model, the From Workspace block reads the structure data from the workspace.

Extended Examples

Load Data Using the From Workspace Block

Load Data Using the From Workspace Block

Load simulation input data using the From Workspace block.

Load Input Data for Basic Test Cases

Load Input Data for Basic Test Cases

Create input data for a basic test of model behavior.

Ports

Output

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Data loaded from workspace, provided at the block output as a signal or a nonvirtual bus. Depending on the data you load, the output signal may be a scalar, vector, multidimensional, or variable-size signal, a bus, or an array of buses (since R2021a). The From Workspace block supports loading real and complex data of all built-in numeric data types and custom fixed-point data types. You can also load string data and data with custom enumerated or bus data types.

Before R2024b: The From Workspace block does not support loading input signal values with int64 or uint64 data types.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus
Complex Number Support: Yes

Parameters

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Data to load from workspace, specified as a MATLAB variable or MATLAB expression that evaluates to data in a format supported by the From Workspace block. The expression could create the data the From Workspace block provides at its output, or the expression could reference a workspace variable that contains the data to load. For more information about how the expression is evaluated, see Symbol Resolution.

The From Workspace block can load real or complex data for scalar, multidimensional, and variable-size signals as well as data for a bus or array of buses.

The From Workspace block supports different input data formats depending on the type of output you want the block to produce in your model. For all types of outputs and data formats:

  • Time values in the input data must have double data type and increase monotonically.

  • Time and data values must not contain Inf or NaN values.

Type of OutputData FormatsTips

Scalar or vector signal

  • timetable that contains a single column (since R2020a)

  • timeseries object

  • Simulink.SimulationData.Signal object

  • Structure with fields and hierarchy that match the Structure or Structure with time logging format.

  • Two-dimensional array in which the first column is time and one or more additional columns contain the signal value for each timestamp

  • For scalar and vector signals, the number of rows in the signal data must match the number of rows in the time vector.

  • To create a timetable, the time values must be a duration vector.

    Simulation time always uses units of seconds. When you create a duration vector that uses units other than seconds, the software converts the value to seconds for use in the simulation.

  • Array format does not support signal values that are complex or that have a data type other than double.

Multidimensional signal

  • timeseries object

  • timetable that contains a single column (since R2020a)

  • Simulink.SimulationData.Signal object

  • Structure with fields and hierarchy that match the Structure or Structure with time logging format

  • For a multidimensional signal with values that have two or more dimensions, the length of the last dimension must match the length of the time vector.

    For example, input data for 10 samples of a 2-by-2 matrix signal has a time vector that contains 10 rows and an array of signal values that has dimensions 2-by-2-by-10.

  • To create a timetable, the time values must be a duration vector.

    Simulation time always uses units of seconds. When you create a duration vector that uses units other than seconds, the software converts the value to seconds for use in the simulation.

Variable-size signal

Structure with fields and hierarchy that match the Structure or Structure with time logging format

To log a variable-size signal in a format you can load using the From Workspace block, connect the signal to a top-level Outport block and set the Format configuration parameter for the model to Structure or Structure with time.

Bus

Structure of timetable (since R2020a) or timeseries objects:

  • Specify the Output data type parameter as the Simulink.Bus object that defines the bus.

  • The hierarchy and field names of the structure must match the hierarchy and element names of the bus.

  • Each timetable or timeseries object contains data for a leaf signal in the bus.

  • Each timetable must contain only one column.

To partially specify input data for a bus, set bus elements for which you do not need to load data to [] in the input data structure.

Array of buses (since R2021a)

Array of structures that each represent data for a bus within the array of buses

  • Loading data for an array of buses is not supported for rapid accelerator simulations.

  • From Workspace blocks in the top model support loading data for an array of buses in normal and accelerator mode simulations.

  • From Workspace blocks in referenced models support loading data for an array of buses only when the referenced model executes in normal mode.

  • To partially specify input data for an array of buses, set bus elements for which you do not need to load data to [] in the structure that represents the data for that bus.

For details, see Load Data Using the From Workspace Block.

Tips

  • To load data that was logged in array format using the To File block, transpose the array so that the time values are in a single column rather than a single row. You can use the transpose function and save the transposed data to a new file.

  • For programmatic simulations you run using the sim, parsim, or batchsim functions, you can use a Simulink.SimulationInput object to specify the data for the From Workspace block to load.

    • Set the value of the VariableName parameter to use in the simulation on the block using the setBlockParameter function.

    • Add the variable that contains the input data to the SimulationInput object using the setVariable function.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Parameter: VariableName
Values: 'simin' (default) | MATLAB expression | timeseries object | timetable | structure | 2-D array
Data Types: char | string

Example: set_param("myModel/From Workspace","VariableName","inData") configures the From Workspace block named From Workspace in the model myModel to load data stored in the MATLAB variable named inData.

Data type of the workspace data the From Workspace block loads. By default, the From Workspace block inherits the output signal data type from the workspace data or from a downstream block that defines the data type for the signal.

Tips

  • When you load data for a scalar, vector, or multidimensional signal, you can choose to inherit the output data type or you can specify the output data type to match the data type of the workspace data.

  • To load data for a bus or an array of buses, set the Output data type to Bus: <bus_object> and specify the name of the Simulink.Bus object that defines the output bus.

    When you load enumerated data, set the Output data type to Enum: <class_name> and specify the name of the enumeration class that defines the enumerated data values.

  • The Data Type Assistant helps you set data attributes. To use the Data Type Assistant, click the Show data type assistant button. For more information, see Specify Data Types Using Data Type Assistant.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Parameter: OutDataTypeStr
Values: 'Inherit: auto' (default) | 'double' | 'single' | 'half' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'boolean' | 'string' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | 'Enum: <class name>' | 'Bus: <object name>' | data type expression
Data Types: char | string

Example: set_param("myModel/From Workspace","OutDataTypeStr","int32") specifies that data type must be int32 for the data the From Workspace block named From Workspace loads into the model myModel.

The Sample time parameter specifies when the block computes a new output value during simulation. For details, see Specify Sample Time.

Specify the Sample time parameter as a scalar when you do not want the output to have a time offset. To add a time offset to the output, specify the Sample time parameter as a 1-by-2 vector where the first element is the sampling period and the second element is the offset.

By default, the Sample time parameter value is 0, which indicates continuous sample time with no time offset. For a discrete signal, specify the Sample time as the discrete sampling interval. For example, specify the Sample time as 0.1 to model a discrete signal sampled every 100ms. Specify the Sample time as -1 to inherit the value.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Parameter: SampleTime
Values: '0' (default) | scalar | vector
Data Types: char | string

Example: set_param("myModel/From Workspace","SampleTime","0.1") configures the From Workspace block named From Workspace in the model myModel to execute with a sample time of 0.1 seconds.

Interpolation method used to provide output values for simulation times that are in between time values in the loaded workspace data. When you select Interpolate data, the From Workspace block linearly interpolates an output value using adjacent values in the loaded workspace data. When Interpolate data is not selected, the From Workspace block provides the value of the previous data point in the loaded workspace data. For more information about the interpolation algorithm, see Interpolation.

The Interpolate data and Form output after final data value by parameters control how the From Workspace block extrapolates output values for simulation times that occur prior to the first data point or after the last data point in the loaded workspace data. For complete information regarding the From Workspace block extrapolation behavior, see Extrapolation.

Clear the Interpolate data parameter and set the Form output after final data value by parameter to a value other than Extrapolation when:

  • You load string, enumerated, fixed-point, or variable-size signal data.

  • You load int64 or uint64 data for a rapid accelerator simulation.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Parameter: Interpolate
Values: 'on' (default) | 'off'
Data Types: char | string

Example: set_param("myModel/From Workspace","Interpolate","off") configures the From Workspace block named From Workspace to use zero-order hold interpolation for loading data into the model myModel.

Zero-crossing detection is a technique used to locate discontinuities in the block output and avoid using excessively small time steps near the discontinuities, which can slow down a simulation. A zero crossing refers to a discontinuity in the data. The From Workspace block can detect zero crossings when the sample time is continuous (0).

The loaded workspace data creates a discontinuity in the block output when the data includes multiple samples with the same time. For example, for this input data, a discontinuity occurs at time 2.

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

The From Workspace block detects zero crossings caused by duplicate time values in the input data only when you select the Interpolation parameter.

The From Workspace block can also create a discontinuity in the output at the last sample in the workspace data when you set Form output after final data value by to Setting to zero.

When you load input data for a bus, the From Workspace block detects zero crossings for all bus elements.

This block supports zero-crossing detection only in simulations that use a variable-step solver. When you use a fixed-step solver for simulation, the software does not detect or locate zero crossings for this block.

For more information, see Zero-Crossing Detection.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Parameter: ZeroCross
Values: 'on' (default) | 'off'
Data Types: char | string

Example: set_param("myModel/From Workspace","ZeroCross","off") disables the Enable zero-crossing detection parameter for the From Workspace block named From Workspace in the model myModel.

The From Workspace block uses the Interpolate data and Form output after final data value by settings to determine the block output for simulation times after the last sample available in the workspace data.

Setting for Form output after final data value bySetting for Interpolate dataBlock Output After Final Data

Extrapolation

On

Extrapolated from final data value

Off

Error

Setting to zero

On

Zero

Off

Holding final value

On

Final value from workspace

Off

Cyclic repetition

On

Error

Off

When the loaded workspace data uses the structure without time format, repeats workspace data from the first value.

Errors for workspace data formats other than structure with time.

For complete information regarding the From Workspace block extrapolation behavior, see Extrapolation.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Parameter: OutputAfterFinalValue
Values: 'Extrapolation' (default) | 'Setting to zero' | 'Holding final value' | 'Cyclic repetition'
Data Types: char | string

Example: set_param("myModel/From Workspace","OutputAfterFinalValue","Holding final value") configures the From Workspace block named From Workspace in the model myModel to use the final input data value as the output value for time steps that occur after the last time value in the input data.

Block Characteristics

Data Types

Boolean | bus | double | enumerated | fixed pointa | half | integer | single | string

Direct Feedthrough

no

Multidimensional Signals

yes

Variable-Size Signals

yes

Zero-Crossing Detection

yes

a Supports input via fi objects created using Fixed-Point Designer.

Algorithms

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Extended Capabilities

Version History

Introduced before R2006a

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See Also

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