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From File

Load data from MAT file into Simulink model

  • Library:
  • Simulink / Sources

  • From File block

Description

The From File block reads data into a Simulink® model from a MAT file and provides the data as a signal or bus at the block output. You can load data from a MAT file that is on or off the MATLAB® path. A model can contain multiple From File blocks that load data from the same MAT file.

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

The From File block icon shows the name of the MAT file that supplies the data to the block. For example, if you use the From File block to load data from the file myData.mat, the block displays myData.mat.

MAT File Data

The From File block can load data from a MAT file that is stored in a timeseries object or in an array where the first row contains time data and subsequent rows contain data for a scalar or vector signal. Loading data stored in a timeseries object supports a wider range of data and output types and requires that the MAT file is Version 7.3.

Note

Logging outputs or states or a signal connected to a To Workspace block using the Array format generates an array in a different format than the From File block expects. In the Array format for logging, the first column contains time values, and in the array format for the From File block, the first row contains time values. The From File block and To File block use the same array format.

Data Consideration

timeseries Format

Array Format

Supported signal data types

  • Any built-in data types except half, int64, and uint64

  • Enumerated data type

  • Fixed-point data type with up to a 32-bit word length

double

Signal data complexity

Real or complex

Real

Signal data requirements

Must not contain NaN, Inf, or -Inf values

Must not contain NaN, Inf, or -Inf values

Type of output

  • Scalar, vector, or multidimensional signal

  • Bus

Scalar or vector signal

Time data requirements

  • Data type must be double

  • Values must increase monotonically

  • Data type must be double

  • Values must increase monotonically

MAT file version

Version 7.3

All versions

The From File block loads data from only one variable in the MAT file, regardless of the number of variables the MAT file contains. When you load data from a Version 7.3 MAT file that contains multiple variables, the From File block loads the data in the variable that is first alphabetically. The ordering algorithm used by Version 7.0 and earlier MAT files is more complicated, so ensure that the MAT file only contains data for a single variable when you load data from a Version 7.0 or earlier MAT file.

MAT File Version

The version of the MAT file also affects how the From File block loads the data. When you load data from a Version 7.3 MAT file, data is loaded incrementally during simulation. When you load data from a Version 7.0 or earlier MAT file, all the data is loaded into memory at the start of simulation.

To convert a MAT file to Version 7.3, use the load function to load the data in the Version 7.0 or earlier MAT file into the base workspace, then save the data to a Version 7.3 MAT file using the save function with the version specified as '-v7.3'. For example, suppose you want to convert the file myData.mat that contains the variable inputData to Version 7.3. Use these commands:

load('myData.mat');
save('myData.mat','inputData','-v7.3');

For more information, see MAT-File Versions.

Ports

Output

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Output created using data loaded from the specified MAT file. Depending on the data you load, the output may be a scalar or multidimensional signal or a bus. The From File block supports loading real and complex data of all built-in data types except half, int64, and uint64.

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

Parameters

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MAT file name or path to MAT file with data you want to load. Specify the path to the file when the file is not on the MATLAB path or in the current working directory.

You can type the path or file name into the text box, or you can browse to the MAT file by clicking the Browse for a MAT-file button. On UNIX® systems, the path can start with a tilde (~), which indicates your home folder.

You cannot load data from a file to which the model logs data.

Tips

  • The From File block supports loading data from a file created using a To File block without any modification to the data or file.

  • To determine the current working directory, enter pwd into the MATLAB Command Window.

  • For information about data requirements for C/C++ code generation with the From File block, see Code Generation.

Programmatic Use

Block Parameter: FileName
Type: character vector
Values: MAT file name | path to MAT file
Default: 'untitled.mat'

Data type of the data in the MAT file loaded by the From File block. By default, the From File block inherits the output signal data type from the data in the file or from a downstream block that defines the data type for the signal. An error occurs if the data type of the data in the MAT file does not match the inherited data type.

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 data in the MAT file.

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

To 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.

Click the Show data type assistant button to display the Data Type Assistant, which helps you set the data type attributes. For more information, see Specify Data Types Using Data Type Assistant.

Programmatic Use

Block Parameter: OutDataTypeStr
Type: character vector
Values: 'Inherit: auto' | 'double' | 'single' | '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'

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

Block Parameter: SampleTime
Type: character vector
Values: scalar | vector
Default: '0'

Extrapolation method used to determine output values for simulation times before the first sample in the MAT file data.

MethodDescriptionExample
Linear extrapolation

How the block determines the output value depends on the type of data in the MAT file.

  • For double data, the From File block linearly extrapolates the output value using the first two samples.

  • For Boolean data, the From File block uses the first value in MAT file data for the output value.

  • For all other built-in data types, the From File block:

    1. Upcasts the data to double.

    2. Linearly extrapolates the output value using the first two samples in the MAT file data.

    3. Downcasts the extrapolated data value to the original data type.

If the MAT file data only contains one sample, the From File block provides that value at the output.

Do not use the Linear extrapolation option when the From File block loads enumerated or fixed-point data.

The extrapolation setting is applied to all signals in a bus. If any signal in the bus contains enumerated or fixed-point data, do not use the Linear extrapolation option.

Plot that shows the output for a From File block configured to linearly extrapolate the output value for simulation times before the first sample in the loaded data. The block loads data that starts 2 seconds into the simulation.

Hold first value

The From File block uses the first data value in the MAT file as the output value.

Plot that shows the output for a From File block configured to hold the first value in the loaded data for simulation times before the first sample in the loaded data. The block loads data that starts 2 seconds into the simulation.

Ground value

The From File block output value depends on the type of data in the MAT file.

  • Built-in numeric types — 0

  • Booleanfalse

  • Fixed-point data types — Representation for value of 0, which may not be exactly 0 due to scaling and limited precision.

  • Enumerated data types — Default value

Plot that shows the output for a From File block configured to use the ground value as the output value for simulation times before the first sample in the loaded data. The block loads data that starts 2 seconds into the simulation.

Tips

To generate code that builds ERT or GRT targets or uses SIL or PIL simulation modes, specify Data extrapolation before first data point as Linear extrapolation. For more information about C/C++ code generation with the From File block, see Code Generation.

Programmatic Use

Block Parameter: ExtrapolationBeforeFirstDataPoint
Type: character vector
Values: 'Linear extrapolation' | 'Hold first value' | 'Ground value'
Default: 'Linear extrapolation'

Interpolation method used to determine output values for simulation times between samples in the MAT file data.

MethodDescriptionExample
Linear interpolation

How the block determines the output value depends on the type of data in the MAT file.

  • For double data, the From File block linearly interpolates the output value using data values before and after the simulation time that needs an output value.

  • For all other built-in numeric data types, the From File block:

    1. Upcasts the data to double.

    2. Linearly interpolates the output value using the MAT file data values before and after the simulation time that needs an output value.

    3. Downcasts the extrapolated data value to the original data type.

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

If the MAT file data only contains one sample, the From File block provides that value at the output.

Do not use the Linear interpolation option when the From File block loads enumerated data.

The interpolation setting is applied to all signals in a bus. If any signal in the bus contains enumerated data, do not use the Linear interpolation option.

Plot that shows the output for a From File block configured to linearly interpolate the output value for simulation times between the samples in the loaded data.

Zero order hold

The From File block holds each data value from one sample to the next. The output value for a simulation time between two samples in the MAT file data is the value of the sample that precedes the simulation time.

Plot that shows the output for a From File block configured to use zero-order-hold interpolation for simulation times between the samples in the loaded data.

Tips

To generate code that builds ERT or GRT targets or uses SIL or PIL simulation modes, specify Data interpolation within time range as Linear interpolation. For more information on C/C++ code generation with the From File block, see Code Generation.

Programmatic Use

Block Parameter: InterpolationWithinTimeRange
Type: character vector
Values: 'Linear interpolation' | 'Zero order hold'
Default: 'Linear interpolation'

Extrapolation method used to determine output values for simulation times after the last sample in the MAT file data.

MethodDescriptionExample
Linear extrapolation

How the block determines the output value depends on the type of data in the MAT file.

  • For double data, the From File block linearly extrapolates the output value using the last two samples in the MAT file.

  • For Boolean data, the From File block uses the sample value in MAT file for the output value.

  • For all other built-in data types, the From File block:

    1. Upcasts the data to double.

    2. Linearly extrapolates the output value using the last two samples in the MAT file data.

    3. Downcasts the extrapolated data value to the original data type.

If the MAT file data only contains one sample, the From File block uses that value as the output.

Do not use the Linear extrapolation option when the From File block loads enumerated data.

The extrapolation setting is applied to all signals in a bus. If any signal in the bus contains enumerated data, do not use the Linear extrapolation option.

Plot that shows the output for a From File block configured to linearly interpolate the output value for simulation times after the last sample in the loaded data. The block loads data that ends 2 seconds before the end of the simulation.

Hold last value

The From File block uses the last data value in the MAT file as the output value.

Plot that shows the output for a From File block configured to hold the last output value for simulation times after the last sample in the loaded data. The block loads data that ends 2 seconds before the end of the simulation.

Ground value

The From File block output value depends on the type of data in the MAT file.

  • Built-in numeric types — 0

  • Booleanfalse

  • Fixed-point data types — Representation for value of 0, which may not be exactly 0 due to scaling and limited precision.

  • Enumerated data types — Default value

Plot that shows the output for a From File block configured to use the ground value as the output value for simulation times after the last sample in the loaded data. The block loads data that ends 2 seconds before the end of the simulation.

Tips

To generate code that builds ERT or GRT targets or uses SIL or PIL simulation modes, specify Data extrapolation after last data point as Linear extrapolation. For more information on C/C++ code generation with the From File block, see Code Generation.

Programmatic Use

Block Parameter: ExtrapolationAfterLastDataPoint
Type: character vector
Values: 'Linear extrapolation' | 'Hold last value' | 'Ground value'
Default: 'Linear extrapolation'

Zero-crossing detection locates discontinuities, or zero crossings, in the block output and prevents excessively small time steps near the discontinuities, which can slow down a simulation. You can enable zero-crossing detection for the From File block when the Sample time parameter is set to 0 for continuous sample time.

The loaded 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 File block can also create discontinuities in the output based on how you configure interpolation and extrapolation.

  • Setting Data extrapolation before first data point to Ground value can create a discontinuity at the first sample in the loaded data.

  • Setting Data extrapolation after the last data point to Ground value can create a discontinuity at the last sample in the loaded data.

  • Setting Data interpolation within time range to Zero-order hold creates a discontinuity at each sample in the loaded data, including the last.

For more information, see Zero-Crossing Detection.

Tips

To generate code that builds ERT or GRT targets or uses SIL or PIL simulation modes, clear this check box. For more information on C/C++ code generation with the From File block, see Code Generation.

Programmatic Use

Block Parameter: ZeroCross
Type: character vector
Values: 'off' | 'on'
Default: 'on'

Block Characteristics

Data Types

Boolean | bus | double | enumerated | fixed point[a] | integer | single

Direct Feedthrough

no

Multidimensional Signals

yes

Variable-Size Signals

no

Zero-Crossing Detection

yes

[a] Supports up to 32-bit fixed-point data types.

Extended Capabilities

Introduced before R2006a