From Workspace

Load signal data from workspace into Simulink model

• Library:

• Simulink / Sources

• 

Description

The From Workspace block reads data into a Simulink^® model from a workspace and provides the data as a signal 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 data is loaded, including the sample time, interpolation and extrapolation behavior, and whether to use zero-crossing detection.

In the model, the From Workspace block 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 in the model.

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.

Ports

Output

Port_1 — Data loaded from workspace

scalar | matrix | bus | array of buses

Data loaded from workspace, provided at the block output as a signal. Depending on the data you load, the output signal may be a scalar, multidimensional, or variable-size signal, a bus, or an array of buses. The From Workspace block supports loading real and complex data of all built-in data types except int64 and uint64.

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

Parameters

Data — Data to load from workspace

timeseries object | timetable object | structure | 2-D array | MATLAB expression

Data to load from workspace, specified as a variable name 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 it 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 data for scalar, multidimensional, and variable-size signals as well as data for a bus or array of buses. The From Workspace block supports loading data in these formats:

• timeseries object

• timetable object

• Simulink.SimulationData.Signal object

• Structure that represents bus data. The structure hierarchy must match the hierarchy of the bus and use timeseries and timetable objects to represent the signal data.

• Structure that represents data for a single signal, with fields and hierarchy that match the Structure or Structure with time logging format.

• Two-dimensional array that represents data for a single signal. The first column in the array represents time and one or more additional columns contain the signal data.

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

When you load data for a bus, specify the Output data type parameter as the Simulink.Bus object that defines the bus.

Real signals of type double can be in any data 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.

The From Workspace block supports loading variable-size signal data in the Structure or Structure with time formats.

Programmatic Use

Block Parameter: VariableName

Type: character vector

Values: MATLAB expression | timeseries object | timetable object | structure | 2-D array

Default: 'simin'

Output data type — Loaded workspace data type

Inherit: auto (default) | double | single | half | int8 | uint8 | int16 | uint16 | int32 | uint32 | boolean | fixdt(1,16,0) | fixdt(1,16,2^0,0) | Enum: <class_name> | Bus: <bus_object> | <data type expression>

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.

When you load data for a scalar 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.

Programmatic Use

Block Parameter: OutDataTypeStr

Type: character vector

Values: 'Inherit: auto' | 'double' | 'single' | 'half' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'boolean' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | 'Enum: <class name>' | 'Bus: <object name>' | '<data type expression>'

Default: 'Inherit: auto'

Sample time — Sample rate of loaded data

0 (default) | scalar | vector

Sample rate of the loaded workspace data. By default, the From Workspace block uses continuous sample time, specified as 0. To inherit sample time from downstream blocks, specify -1. For discrete input data, specify the sample rate.

For more information, see Specify Sample Time.

Programmatic Use

Block Parameter: SampleTime

Type: character vector

Values: scalar | vector

Default: '0'

Interpolate data — Interpolation method

on (default) | off

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.

When you load enumerated, fixed-point, or variable-size signal data, clear the Interpolate data parameter.

To provide output values after the last value in the loaded workspace data, the From Workspace block uses a combination of the Interpolate data parameter and the Form output after final data value by parameter.

The Interpolate data parameter value also affects how the From Workspace block extrapolates output values for simulation times prior to the first data point in the loaded workspace data. When Interpolate data is selected, the From Workspace block uses the first two data points in the workspace data to linearly extrapolate output values for simulation times prior to the first data point. When Interpolate data is not selected, the block provides ground as the output value for simulation times prior to the first workspace data point. For complete information regarding the From Workspace block extrapolation behavior, see Extrapolation.

Programmatic Use

Block Parameter: Interpolate

Type: character vector

Values: 'off' | 'on'

Default: 'on'

Enable zero-crossing detection — Zero-crossing detection

on (default) | off

Zero-crossing detection is a technique used to locate discontinuities and avoid using excessively small time steps near the discontinuity, which can slow down a simulation. A zero crossing refers to the discontinuity in the data. You can enable zero-crossing detection for the From Workspace block when the sample time is continuous.

The From Workspace block detects zero crossings in the loaded workspace data when the data includes multiple samples with the same time. For example, suppose this is the workspace data:

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

The From Workspace block detects a zero crossing at time 2 due to the discontinuity in the input data.

The From Workspace block also detects the zero crossing that may occur after the last data point in the workspace data when you configure the block to set the output to zero after the final workspace data point. For example, if the last loaded data value is 3 and the block is configured to set the output to zero after the final workspace data point, setting the value to zero creates a discontinuity that the From Workspace block detects as a zero crossing.

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

For more information, see Zero-Crossing Detection.

Programmatic Use

Block Parameter: ZeroCross

Type: character vector

Values: 'off' | 'on'

Default: 'on'

Form output after final data value by — Method to determine block output after final data point

Extrapolation (default) | Setting to zero | Holding final value | Cyclic repetition

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 by	Setting for Interpolate data	Block 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

Block Parameter: OutputAfterFinalValue

Type: character vector

Values: 'Extrapolation' | 'Setting to zero' | 'Holding final value' | 'Cyclic repetition'

Default: 'Extrapolation'

Model Examples

Read Structure From Workspace Using Model Sample Time

Read a structure from the MATLAB workspace using a sample time specified in the From Workspace block.

Open Model

Read 2-D Signals in Structure Format From Workspace

Read a 2-D structure from the MATLAB workspace.

Open Model

Block Characteristics

Data Types	Boolean | bus | double | enumerated | fixed point[a] | 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.

Tips

• The From Workspace block supports loading partially specified data for a bus. To partially specify bus data, set bus elements for which you do not need to load data to [].

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

Algorithms

Interpolation

Interpolation is the process the From Workspace block uses to provide output values for simulation times that are between sample times in the loaded workspace data. When you select Interpolate data, the From Workspace block linearly interpolates the output value using two adjacent points in the workspace data. When you do not select Interpolate data, the From Workspace block uses the value of the prior workspace data point as the output value. For example, this model has one From Workspace block with Interpolate data selected and another with Interpolate data cleared. Both blocks load the same sine wave data from the base workspace.

When you select the Interpolate data parameter, the From Workspace block performs different steps, depending on the type of data you load.

For double data, the From Workspace block linearly interpolates the value using the workspace data values before and after the simulation time.

For Boolean data, if the simulation time is between two workspace data points with different values, the From Workspace block positions the value transition halfway between the workspace data points. For example, if the workspace data transitions from true to false, the From Workspace data provides an output value of true for simulation times in the first half of the interval between the workspace data points and provides an output value of false for simulation times in the latter half of the interval.

For built-in data types other than double and Boolean, the From Workspace block performs these steps:

1. Upcast the data to double data type.

2. Linearly interpolate the output value using the double values.

3. Downcast the interpolated value to the original data type.

Extrapolation

Extrapolation is the process the From Workspace block uses to provide output values for simulation times that are before the first data point and after the last data point in the loaded workspace data. You can control how the From Workspace block extrapolates output values before the first workspace data value using the Interpolate data parameter. Use the Interpolate data and Form output after final data value by parameters to specify how the block extrapolates output values for simulation times after the final workspace data point.

Interpolate data	Output Before First Data Point	Form output value after final data by	Output After Final Data Point
On	Linearly extrapolated using first two workspace data points	Extrapolation	Linearly extrapolated using final two workspace data values
		Setting to zero	Zero
		Holding final value	Final workspace data value
		Cyclic repetition	Error
Off	Zero	Extrapolation	Error
		Setting to zero	Zero
		Holding final data value	Final workspace data value
		Cyclic repetition	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 example, consider this model that has a From Workspace block with Interpolate data enabled and Form output after final data value by set to Extrapolation. The From Workspace block reads workspace data that was created by logging the output of the Sine Wave block for a 16-second simulation. The Dashboard Scope blocks display the Sine Wave block output and the From Workspace block output for a 20-second simulation. After the simulation reaches 16 seconds, the From Workspace block output diverges from the Sine Wave block output as the From Workspace block linearly extrapolates output values for the remainder of the simulation.

Extended Capabilities

Fixed-Point Conversion

Design and simulate fixed-point systems using Fixed-Point Designer™.

Supports input via fi (Fixed-Point Designer) objects created using Fixed-Point Designer™.