Record

View and log data to the workspace, a file, or both

Since R2021a

• 

Libraries:
Simulink / Sinks

Alternative Configurations of Record Block:
XY Graph

Description

Use the Record block or the XY Graph block to record data to the workspace, a file, or to both the workspace and a file. When you log data to a file, you can choose to log to a MAT file, an MLDATX file, an Excel^® file, or a Parquet file (since R2025a). Signals connected to a Record block always log to the Simulation Data Inspector. If you decide that you need to save data after simulation, you can export data from the Record block to the workspace or to any supported file type except a Parquet file.

You can also use the Record block to visualize connected signals. To view data for signals connected to the Record block, double-click the block. You have access to simulation controls, such as the Run button, while viewing data in the Record block.

By default, the Record block displays all connected signals on a sparklines plot. A sparkline is added for each connected signal. After sparklines fill the visible space, a scrollbar allows you to continue plotting signals.

Build Visualizations

The Record block supports most visualizations available in the Simulation Data Inspector. When a different visualization makes sense for your data, you can modify the plot layout and plot types using the Layouts option and the plot types selector, labeled Sparklines by default. Use the Layouts list to select a layout of subplots. To change the plot type of a subplot, select the subplot then select the desired plot type from the plot types selector.

For more information, see Log Data to the Workspace and a File Using the Record Block. For examples that show how to use each visualization type, see:

• Sparklines — View Many Signals Together Using Sparklines

• XY — Visualize Simulation Data on XY Plot and Analyze Data Using XY Plot

• Map — View and Replay Map Data

• Time plot and text editor — Create Plots Using the Simulation Data Inspector

Examples

Log Data to the Workspace and a File Using the Record Block

Use the Record block to log data to the workspace, to a file, or to both the workspace and a file.

• Open Model

Export Data to Parquet File Using Record Block

Use the Record block to export data to a Parquet file.

Plot a Circle Using the XY Graph Block

Plot x and y data for a circle using the XY Graph block.

• Open Live Script

Load Data Using Playback Block

Load data from the workspace, a file, and the Simulation Data Inspector using the Playback block.

• Open Live Script

Limitations

• The Record block does not support the array visualization available in the Simulation Data Inspector.

• The Record block supports logging multidimensional signal data, including variable-size signals, but does not support visualizing multidimensional data. To visualize the data for a multidimensional signal using the Record block, convert the signal with multidimensional sample values to a set of signals, called channels, that each have scalar sample values. For more information, see Analyze Multidimensional Signal Data.

• In R2025a: Live streaming is not supported for XY plots in external mode.

Ports

Input

Port_1 — Signal to record

scalar | vector | matrix | array | bus

Signal to record. You can add ports to the Record block by dragging lines to the edge of the block or by using the Ports parameter.

The Record block supports logging variable-size signals but does not support visualizing variable-size signals.

The XY Graph block is an alternative configuration of the Record block that visualizes data connected to two input ports on an XY plot. The first input port provides the x data for the XY plot, and the second input port provides the y data.

Tips

• To log frame-based data, specify the Input processing parameter for each port that receives a frame-based signal.

• When you connect a nonscalar signal to an input port of the XY Graph block, you must manually configure which channels or elements of the nonscalar signal provide the x and y data for the XY plot.

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

Parameters

To edit block parameters interactively, use the Property Inspector. From the Simulink^® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Main

Number of input ports — Number of input ports

1 (default) | integer in the range [1,100]

Number of input ports, specified as an integer between 1 and 100, inclusive.

The XY Graph block is an alternative configuration of the Record block that visualizes data connected to two input ports on an XY plot. In the XY Graphblock, the first input port provides the x data, and the second input port provides the y data.

Programmatic Use

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

Parameter:	NumPorts
Values:	1 (default) | integer in the range [1, 100]
Data Types:	integer

Example: set_param("myModel/Record","NumPorts",2)

Decimation — Decimation factor

1 (default) | positive integer

Since R2025a

Specify a decimation factor to reduce the effective sample rate for the logged data. For a decimation factor, n, the Record block logs every n^th sample value. For example, when you specify the Decimation value as 2, the Record block logs every other data point.

For more information about controlling which samples are logged during simulation, see Specify Signal Values to Log.

Programmatic Use

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

Parameter:	Decimation
Values:	"1" (default) | positive integer in quotes
Data Types:	character vector | string

Example: set_param("myModel/Record","Decimation","2")

Limit data points to last — Number of samples to log

inf (default) | scalar | vector

Since R2025a

When you want to save or analyze only the data from the end of a simulation, specify the number of samples you want to log as a positive integer greater than zero. By default, the Record block logs data for the entire simulation, and the value for the Limit data points to last parameter is inf.

Limiting logged data to the last n signal values directly impacts memory allocation. When you specify this parameter, the software allocates memory upfront based on the specified value, not on the time steps generated during the simulation. For this reason, the Limit data points to last parameter is not recommended when logging an indeterminate number of time steps.

For more information about controlling which samples are logged during simulation, see Specify Signal Values to Log.

Programmatic Use

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

Parameter:	MaxDataPoints
Values:	"inf" (default) | positive integer in quotes
Data Types:	character vector | string

Example: set_param("myModel/Record","MaxDataPoints","20")

Select port — Port for which to specify input processing mode

1 (default) | integer

Use the Select port and Input processing parameters together to specify the input processing mode for a port. The input processing mode determines how the Record block interprets matrix data:

• Sample-based — Each element in the matrix is a separate channel.

• Frame-based — Each column in the matrix is a separate channel.

To use frame-based input processing, the signal must have a discrete sample rate, and the sample values must be nonscalar with fixed dimensions.

By default, each port processes the input signal as sample-based.

To change the input processing mode for a port:

1. Select the port number using the Select port parameter.

2. Select the input processing mode using the Input processing parameter.

Programmatic Use

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

Programmatically specify the input processing mode for each port by specifying the FrameSettings parameter as a row vector with as many elements as block ports. The element index corresponds to the port number on the block. Specify 1 to use frame-based input processing for the port and 0 to use sample-based processing.

Parameter:	FrameSettings
Values:	false (default) | 1-by-n row vector of logical values, where n is equal to the number of ports
Data Types:	logical array

Example: set_param("myModel/Record","FrameSettings",[true,false,true])

Input processing — Input processing mode for selected port

Elements as channels (sample-based) (default) | Columns as channels (frame-based)

Use the Select port and Input processing parameters together to specify the input processing mode for a port. The input processing mode determines how the Record block interprets matrix data:

• Sample-based — Each element in the matrix is a separate channel.

• Frame-based — Each column in the matrix is a separate channel.

To use frame-based input processing, the signal must have a discrete sample rate, and the sample values must be nonscalar with fixed dimensions.

By default, each port processes the input signal as sample-based.

To change the input processing mode for a port:

1. Select the port number using the Select port parameter.

2. Select the input processing mode using the Input processing parameter.

Programmatic Use

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

Programmatically specify the input processing mode for each port by specifying the FrameSettings parameter as a row vector with as many elements as block ports. The element index corresponds to the port number on the block. Specify 1 to use frame-based input processing for the port and 0 to use sample-based processing.

Parameter:	FrameSettings
Values:	false (default) | 1-by-n row vector of logical values, where n is equal to the number of ports
Data Types:	logical array

Example: set_param("myModel/Record","FrameSettings"[true,false,true])

Record

Record to workspace — Workspace logging option

off (default) | on

Workspace logging option. By default, the Record block logs data only to the Simulation Data Inspector. Select Record to workspace to log data for signals connected to the Record block to the MATLAB^® workspace in a Simulink.SimulationData.Dataset object.

Use the Workspace variable name parameter to specify the name of the Dataset object that contains the logged Record block data.

Tips

• When you log data to the workspace, the way you access the data depends on your model configuration. By default, models provide all logged data in a single output variable as a Simulink.SimulationOutput object. You can access the Record block data using the get function or a dot with the Record block workspace variable name. When the Single simulation output option is disabled, logging data appears in separate variables in the workspace, and you access the Record block data directly.

• Logging intervals specified using the Logging intervals configuration parameter apply to data logged to the workspace using the Record block.

• Use a single Record block to log data to the Simulation Data Inspector, the workspace, and a file.

Programmatic Use

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

Parameter:	RecordToWorkspace
Values:	"off" (default) | "on" | false or 0 | true or 1

Example: set_param("myModel/Record","RecordToWorkspace","on")

Workspace variable name — Name for workspace variable that contains logged block data

recordout (default) | character vector | string

Name for the workspace variable that contains the logged block data.

Dependencies

To enable this parameter, select the Record to workspace parameter.

Programmatic Use

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

Parameter:	VariableName
Values:	"recordout" (default) | valid MATLAB variable name
Data Types:	character vector | string

Example: set_param("myModel/Record","VariableName","RecordedData")

Record to file — Log to file option

off (default) | on

Log to file option. By default, the Record block logs data to the Simulation Data Inspector only. Select Record to file to log data for signals connected to the Record block to a file.

Tips

• Use the File name parameter to specify a name for the file.

• Use the File type parameter to specify whether to log data to an MLDATX file, a MAT file, an Excel file, or a Parquet file (since R2025a).

• Use the File location parameter to specify the path to the file.

• Logging intervals specified using the Logging intervals configuration parameter do not apply to data logged to a file using the Record block.

Programmatic Use

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

Parameter:	RecordToFile
Values:	"off" (default) | "on" | false or 0 | true or 1

Example: set_param("myModel/Record","RecordToFile","on")

File name — Name of file with logged data

recording.mldatx (default) | character vector | string

Name of the file that contains the logged data. The name does not need to include the file extension. If you do include the file extension in the name, ensure the name uses a valid extension for the specified File type.

Tips

• If you do not change the name or location of the file you log to from one run to the next, the Record block overwrites prior data in the file.

• When you want to save the file in a location other than your working directory, use the File location parameter to specify the path to the directory where you want to save the file.

Dependencies

To enable this parameter, select the Record to file parameter.

Programmatic Use

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

Specify the File name, File type, and File location parameters. Include the extension for the desired file type in the name you pass to set_param. When you want to save the file somewhere other than the current working directory, specify the path with the filename and extension.

Parameter:	FileName
Values:	"recording.mldatx" (default) | valid filename
Data Types:	character vector | string

Example: set_param("myModel/Record","FileName","myRecording.mldatx")

File type — Type of file for logged data

*.mldatx (default) | *.mat | *.xslx | *.parquet

Use the File type parameter to specify whether you want to log data to an MLDATX, MAT, Excel, or Parquet file (since R2025a).

Tips

• When you log data to an Excel file, the data is formatted as described in Microsoft Excel Import, Export, and Logging Format.

• When you log data to an Excel file, you can specify whether to share time columns using the Time parameter and which signal attributes to log using the Attributes parameter.

Dependencies

To enable this parameter, select Record to file.

Programmatic Use

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

Use the FileName parameter to specify the File name, File type, and File location parameters. Include the extension for the desired file type in the name you pass to set_param. When you want to save the file somewhere other than the current working directory, specify the path with the filename and extension.

Parameter:	FileName
Values:	"recording.mldatx" (default) | valid filename
Data Types:	character vector | string

Example: set_param("myModel/Record","FileName","myRecording.parquet")

File location — Path to file with logged data

working directory (default) | character vector | string

Use the File location parameter to specify the location where you want to save the file with the logged data when you want to save the file somewhere other than the working directory. Ensure you have write permissions in the directory you specify.

Dependencies

To enable this parameter, select Record to file.

Programmatic Use

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

Use the FileName parameter to specify the File name, File type, and File location parameters. Include the extension for the desired file type in the name you pass to set_param. When you want to save the file somewhere other than the current working directory, specify the path with the filename and extension.

Parameter:	FileName
Values:	"recording.mldatx" (default) | valid filename
Data Types:	character vector | string

Example: set_param("myModel/Record","FileName","myRecording.mldatx")

Time — Options for exporting time data to Excel or Parquet file

Shared Time Columns (default) | Individual Time Columns

Specify how to log signal time data when you log the Record block data to an Excel file or Parquet file (since R2025a).

• Shared Time Columns — When time data is identical for multiple signals, the signals share a single time column in the logging file. The logging file can still include multiple time columns if the Record block logs data for signals with unique time data.

• Individual Time Columns — Each logged signal always has its own time column in the logging file.

Dependencies

To enable this parameter, select Record to file and specify File type as *.xlsx or *.parquet (since R2025a).

Programmatic Use

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

Programmatically setting the Time parameter is supported only for Parquet files.

Parameter:	SharedTimeColumn
Values:	"on" (default) | "off"

Example: set_param("myModel/Record","SharedTimeColumn", "off")

Signal Attributes — Signal attributes to export to Excel file

Data Type | Units | Port Index | Block Path | Interpolation

Select one or more signal attribute options to include in the logging file when you log data to an Excel file. Selected signal attributes appear in the signal column above the first data point according to the format described in Microsoft Excel Import, Export, and Logging Format.

Dependencies

To enable this parameter, select Record to file and specify File type as *.xlsx.

Compression Type — Compression options

Fastest (snappy) (default) | Balanced for Size and Speed (gzip) | Compact (brotli) | None (uncompressed)

Since R2025a

Specify compression as one of these options:

• Fastest (snappy) — Similar save speed to an uncompressed file, smaller file size

• Balanced for Size and Speed (gzip) — Balance between file size and save speed

• Compact (brotli) — Smallest file size, slowest save speed

• None (uncompressed) — Largest file size, fastest save speed

Dependencies

To enable this parameter, select Record to file and specify File type as *.parquet.

Programmatic Use

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

Parameter:	ParquetCompression
Values:	"fastest" (default) | "balanced" | "compact" | "none"

Example: set_param("myModel/Record","ParquetCompression","balanced")

Generate Sidecar — Option to generate JSON sidecar

on (default) | off

Since R2025a

Select this parameter to generate a JSON sidecar that contains all the logged metadata.

Dependencies

To enable this parameter, select Record to file and specify File type as *.parquet.

Programmatic Use

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

Parameter:	ParquetMetaData
Values:	"on" (default) | "off"

Example: set_param("myModel/Record","ParquetMetaData","off")

Row Group Policy — Options for grouping rows in Parquet file

Row Group Height (default) | Row Group Size (MB)

Since R2025a

Specify row groups in the Parquet file.

• Row Group Height — Specify the number of rows per group.

• Row Group Size (MB) — Specify the size of the row group in megabytes.

Dependencies

To enable this parameter, select Record to file and specify File type as *.parquet.

Programmatic Use

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

Parameter:	ParquetRowGroupPolicy
Values:	"height" (default) | "sizeinmb"

Example: set_param("myModel/Record","ParquetRowGroupPolicy","sizeinmb")

Row Group Policy Value — Height or size of row group

auto (default when Row Group Policy is Row Group Height) | 512 (default when Row Group Policy is Row Group Size (MB) | number of rows | size of row group

Since R2025a

To specify the number of rows in each row group, set the Row Group Policy parameter to Row Group Height. Then, use the Row Group Policy Value parameter to define the number of rows in each group, choosing a value between 1 and 67,108,864. By default, the value is auto, which creates the largest possible row group without exceeding 512 MB.

To specify the size of each row group, set the Row Group Policy parameter to Row Group Size (MB). Then, use the Row Group Policy Value parameter to set the data size of the row group in megabytes, up to 1GB.

Dependencies

To enable this parameter, select Record to file and specify File type as *.parquet.

Programmatic Use

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

Parameter:	ParquetRowGroupHeight
Values:	"auto" (default) | integer in the range [1, 67108864] in quotes
Data Types:	character vector | string

Example: set_param("myModel/Record","ParquetRowGroupPolicy","height","ParquetRowGroupHeight","5000")

Parameter:	ParquetRowGroupSize
Values:	"512" (default) | positive number in the range (0, 1000] in quotes
Data Types:	character vector | string

Example: set_param("myModel/Record","ParquetRowGroupPolicy","sizeinmb","ParquetRowGroupsize","450")

Block Characteristics

Data Types	Boolean | bus | double | enumerated | fixed point | half | integer | single | string
Direct Feedthrough	no
Multidimensional Signals	yes
Variable-Size Signals	yes
Zero-Crossing Detection	no

Alternative Configurations

XY Graph — Log and visualize two input signals on XY plot

The XY Graph block in the Simulink Sinks library is an alternative configuration of the Record block that visualizes two input signals on an XY plot. The first input port provides the x data for the XY plot. The second input port provides the y data.

The XY Graph block supports logging and visualizing data for nonscalar inputs. However, the XY visualization does not support multidimensional data. When you connect nonscalar signals to the XY Graph block, you must manually configure which channels or elements of the nonscalar signal provide the x and y data for the XY plot.

Libraries:
Simulink / Sinks
HDL Coder / Sinks

Tips

• To open the Record block in a new window, right-click the block, then select Open In New Window.

• To open the Record block in a new tab, right-click the block, then select Open In New Tab.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

This block is ignored for code generation.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Architecture

Architecture	Description
No HDL	Do not generate HDL code for this block.

HDL Block Properties

PreserveUpstreamLogic

Control the removal of unconnected logic. The default is off, which means unconnected logic is not preserved in HDL code. For more details, see PreserveUpstreamLogic (HDL Coder).

PLC Code Generation

Generate Structured Text code using Simulink® PLC Coder™.

This block is ignored for code generation.

Version History

Introduced in R2021a

R2025a: Log datetime data

The Record block supports logging datetime data.

R2025a: Live streaming no longer supported in XY visualizations

To avoid scalability issues, data is no longer streamed to XY visualizations in the Simulation Data Inspector, Record block, or XY Graph block.

R2025a: Limit data logged by Record block

Limit the size of data logged by the Record block by specifying signal values to log. You can specify signal values to log using these two parameters:

• Decimation — Log every nth signal value.

• Limit data points to last — Log only the last n signal values.

R2025a: Export data to a Parquet file using the Record block

Use the Record block to export data from scalar and multidimensional signals, as well as data from buses or arrays of buses, to a Parquet file. The Record block logs and can export real and complex data of any built-in data type, as well as enumerations, strings, and fixed-point data. For more information, see Export Data to Parquet File Using Record Block.

R2023b: Log unbounded variable-size signals

In normal and accelerator mode simulations, the Record block supports logging unbounded variable-size signals but does not support visualizing unbounded-variable-size signals. Logging is not supported for nonvirtual buses that contain unbounded variable-size signals.

R2023a: Log nonvirtual buses that contain variable-size signals

In normal and accelerator mode simulations, the Record block supports logging:

• Nonvirtual buses that contain variable-size signals directly or in nested buses

• Buses with nested nonvirtual buses that contain variable-size signals

In normal mode simulations only, the Record block supports logging:

• Arrays of buses with nonvirtual buses that contain variable-size signals

The Record block does not support visualizing variable-size signals.

R2022b: Scale individual signals

You can set the display scale and offset for an individual signal in the Record block.

• Time plots and sparklines — Scale and offset the display of y values.

• XY plots — Scale and offset the display of the x values and y values independently.

• Maps — Scale and offset the longitude and latitude independently.

Cursors continue to show the unscaled values.

R2021b: XY Graph block replaced with alternative configuration of the Record block

The XY Graph block is replaced with a Record block that is preconfigured to display two input signals on an XY plot. Using the updated XY Graph block, you can:

• View data on the XY plot during simulation.

• Record the XY plot data to the workspace, a file, or the workspace and a file.

• Zoom, pan, fit to view, and adjust the axis limits for the XY plot without having to simulate again.

• Analyze the XY trace by using cursors and by adding a trend line.

• Add additional ports and subplots to visualize additional simulation data alongside the XY plot on several visualization types, including time plots, maps, or additional XY plots.

• Visualize multiple traces on the XY plot.

Upon simulation, the prior version of the XY Graph block opened a new window to display the connected signal data during simulation. To view data on the updated XY Graph block, double-click the block in the model. To view the XY plot in a new window, right-click the block and select Open in New Window.

XY Graph blocks in existing models are automatically replaced with the new XY Graph block. XY Graph viewers are also replaced with the new XY Graph block. Goto and From blocks connect signals to the XY Graph block that replaces the XY Graph viewer.

Signals connected to an XY Graph block always stream to the Simulation Data Inspector.

R2021a: Logging intervals configuration parameter applies to data logged to the workspace using the Record block

The Logging intervals configuration parameter applies to data logged to the workspace using the Record block.

The Logging intervals parameter does not affect data logged to a file using the Record block or how signals are displayed in the Record block. You can also access complete signal data for signals connected to the Record block in the Simulation Data Inspector.