Callback Button

Execute MATLAB code using button

• 

Libraries:
Simulink / Dashboard

Description

The Callback Button block executes MATLAB^® code in response to a click or a press of the button. When you press the button, the code executes after a time span that you specify has elapsed or at time intervals that you specify. You can configure the block to execute different code for a click versus for a press. When you use the Callback Button block from the Customizable Blocks library, you can also customize the appearance of the block to look like a button in your real system.

To push the virtual button, click the Callback Button block. While you press your pointer, the button is pushed. When you release your pointer, you release the button.

You can use callback functions to specify what you want the button to do:

• PressFcns functions run while the button is pushed. You can configure the button to run the PressFcn function only once while the button is pushed, or you can specify a repeat interval.

• ClickFcns functions run when you release the button.

You can configure the button to stay pushed when you release your pointer by setting the Button Type to Latched. When you choose the latched button type:

• To latch the button, click the button.

• To unlatch the button, click the button again.

The PressFcn function runs while the button is latched. The ClickFcn function runs once when you latch the button, and once when you unlatch the button.

You can use states to specify how the appearance of the Callback Button block changes when you interact with the button:

• While you push the button, the block is in the Pressed state.

• When the button is latched and you are not pushing it, the block is in the Latched state.

• When the button is latched and you are pushing it, the block is in the Latched and Pressed state.

• When the block is not in any of these three states, it is in the Default state.

A state pairs pointer actions with:

• A State Label

• A state icon

• A state image

Note

Double-clicking the Callback Button block does not open its dialog box during simulation or when the block is selected. To edit the block parameters, you can use the Property Inspector or open the block dialog box by:

• Double-clicking the block when the block is not selected and the model is not simulating

• Right-clicking the block and selecting Block Parameters from the context menu

Customize Callback Button Blocks

When you add a Callback Button block to your model, the block is preconfigured with a default design. You can use the block with the default design or customize the appearance of the block.

To customize the appearance of the block, use design mode. After selecting the block, you can enter design mode in one of three ways:

• In the Simulink^® Toolstrip, on the block-specific tab, under Design, click Edit.

• In the Property Inspector, on the Design tab, click Edit.

• Pause on the ellipsis that appears over the block and click the Edit Custom Block button .

When you design a Callback Button block, you configure the block appearance for each possible state. When you configure the Block Type as Momentary, the block has two states. When you configure the Block Type as Latch, the block has four.

You can use the toolbar above the block to switch states. For each state, you can:

• Upload a state image.

• Upload a state icon and specify the position of the icon relative to the state label.

• Specify the State Label text, color, opacity, and position.

You can also upload a foreground or a background image, or set a solid background color. The foreground and background apply to all states.

Use the toolbar above the block to configure the image, the icon, and the State Label color and opacity.

You can use the Design tab in the Property Inspector for fine control over the block design and to enter exact values for design settings.

Use the Design tab to:

• Specify the State Label text and position.

• Specify the icon position.

• Upload a foreground image.

• Upload a background image.

• Set a solid background color.

When you finish editing the design, to exit design mode, click the X in the upper right of the canvas.

Examples

Change Gain Value Using Callback Button Block

You can use a Callback Button block to control a parameter value before or during simulation. For example, in the model callbackGain, three Callback Button blocks are configured to set the Gain parameter of the Gain block to a value of 5, 10, or 15.

Simulate the model. To change the gain value, click the Callback Button blocks.

Extended Examples

Initialize Your Model Using the Callback Button Block

Use the Callback Button block to perform initialization routines on your model.

• Open Model

Parameters

Use the Property Inspector and the Block Parameters dialog box to specify the values of the block parameters. To set the core parameters of the dashboard block, use the Block Parameters dialog box or the Parameters tab in the Property Inspector. To customize the block, use the Design tab in the Property Inspector. To open the Block Parameters dialog box for a block, double-click the block. To open the Property Inspector, on the Modeling tab, under Design, select Property Inspector.

Parameters

To set the core parameters of the dashboard block, open the Property Inspector and click the Parameters tab.

Main

Button Type — Button response to click

Momentary (default) | Latch

Specify how the block responds to a click.

• Momentary — The button changes state only while pressed. When you release the click, the button returns to its default state.

• Latch — The button latches the state change when clicked. The button remains in the pressed state until you click it again.

When you configure Button Type as Momentary, the block has these states:

• Default — Default state for the block when it is not pressed

• Pressed — Block state when the block is pressed

When you configure Button Type as Latch, the block has these states:

• Default — Default state for the block when it is not pressed.

• Pressed — Transitional state when you press the button while it is in the Default state. The block transitions to the Latched state when you release the click.

• Latched — Latched state for the block when it is not pressed.

• Latched and Pressed — Transitional state when you press the button while it is in the Latched state. The block transitions to the Default state when you release the click.

Programmatic Use

Block Parameter: ButtonType

Type: string or character array

Value: 'Momentary' | 'Latch'

Text — Button label text

'Callback Button' (default) | string | character array

Specify the text for the button label. The label is applied to the button for the state that is selected in the Select State section of the States component on the Design tab.

Programmatic Use

Specify the ButtonText parameter for the block as a string or a character vector.

Block Parameter: ButtonText

Type: character vector | string

Lock Aspect Ratio — Option to maintain block aspect ratio

on (default) | off

Select this parameter to maintain the aspect ratio when resizing the block in the Simulink canvas.

When the aspect ratio is locked, adding a new background image changes the aspect ratio of the block to match the aspect ratio of the background image. When the aspect ratio is unlocked, adding a new background image does not change the aspect ratio of the block, but instead changes the aspect ratio of the background image to fit the size of the block.

When the aspect ratio is locked, pressing the Shift key while resizing a block temporarily unlocks the aspect ratio. When you release the Shift key, the aspect ratio locks. When the aspect ratio is unlocked, pressing the Shift key while resizing a block temporarily locks the aspect ratio. When you release the Shift key, the aspect ratio unlocks.

Callbacks

ClickFcn — MATLAB code that executes in response to click

MATLAB code

MATLAB code that executes in response to a click of the button.

Every time you click the button, the ClickFcn code executes once, at the point in time when you release the click.

To specify code for the ClickFcn, select ClickFcn from the drop-down menu. Enter the code in the text box below the menu.

Programmatic Use

Specify the ClickFcn parameter for the block as MATLAB code that is formatted as a string or a character vector.

Block Parameter: ClickFcn

Type: character vector | string

Values: MATLAB code

PressFcn — MATLAB code that executes in response to press

MATLAB code

MATLAB code that executes in response to a press of the button.

While the button is in the pressed state, the PressFcn code executes once when the Press Delay time has elapsed and periodically at every Repeat Interval.

To specify code for the PressFcn, select PressFcn from the drop-down menu. Enter the code in the text box below the menu.

How you press the button to execute the PressFcn code depends on the Button Type.

• If the Button Type is Momentary, hold down your click for the duration that you want to press the button.

• If the Button Type is Latch, click to press the button, but do not hold down your click. The button remains pressed until you click it again.

Note

Every time that you click on the button, even when you do so as part of the process for pressing the button, the ClickFcn code executes once, at the point in time when you release the click.

Programmatic Use

Specify the PressFcn parameter for the block as MATLAB code that is formatted as a string or a character vector.

Block Parameter: PressFcn

Type: character vector | string

Values: MATLAB code

Press Delay (ms) — Time to hold button for press

500 (default) | scalar

Amount of time required to cause the PressFcn code to execute.

Dependencies

Press Delay (ms) is visible only when PressFcn is selected as the callback.

Programmatic Use

Specify the PressDelay parameter for the block as a positive scalar value.

Block Parameter: PressDelay

Type: scalar

Repeat Interval (ms) — Time interval to repeat PressFcn code

0 (default) | scalar

Time interval after which the PressFcn code executes again if the Callback Button block is still pressed.

Dependencies

Repeat Interval (ms) is visible only when PressFcn is selected as the callback.

Programmatic Use

Specify the RepeatInterval parameter for the block as a positive scalar value.

Block Parameter: RepeatInterval

Type: scalar

Design

To customize the dashboard block, open the Property Inspector, click the Design tab, and click Edit.

Button

Lock Aspect Ratio — Option to maintain block aspect ratio

on (default) | off

Select this parameter to maintain the aspect ratio when resizing the block in the Simulink canvas.

When the aspect ratio is locked, adding a new background image changes the aspect ratio of the block to match that of the background image. When the aspect ratio is unlocked, adding a new background image does not change the proportions of the block but instead stretches or scales the background image to fit the size of the block.

When the aspect ratio is locked, pressing the Shift key while resizing a block unlocks the aspect ratio. When you release the Shift key, the aspect ratio locks. When the aspect ratio is unlocked, pressing the Shift key while resizing a block locks the aspect ratio. When you release the Shift key, the aspect ratio unlocks.

States

Select State — Selection of state to configure

Default (default) | Pressed | Latched | Latched and Pressed

Select a state that you want to configure from the drop-down menu in the Select State section of the States component. When the Button Type is Momentary, you can select these states:

• Default — Default state for the block when it is not pressed

• Pressed — Block state when the block is pressed

When the Button Type is Latch, you can select these states:

• Default — Default state for the block when it is not pressed.

• Pressed — Transitional state when you press the button while it is in the Default state. The block transitions to the Latched state when you release the click.

• Latched — Latched state for the block when it is not pressed.

• Latched and Pressed — Transitional state when you press the button while it is in the Latched state. The block transitions to the Default state when you release the click.

Note

You can configure all of the parameters in the States component of the Design tab for a state. For example, you can select an icon that will appear on the button when it is in the state. When you configure any of the parameters in the States component, the changes are applied to the state that is selected in the Select State section of the States component.

Example: Pressed

Text — Button label text

'Callback Button' (default) | string | character array

Specify the text for the button label. The label is applied to the button for the state that is selected in the Select State section of the States component on the Design tab.

Programmatic Use

Specify the ButtonText parameter for the block as a string or a character vector.

Block Parameter: ButtonText

Type: character vector | string

Color — Label font color

[r g b] vector

Choose a font color for the label text from the palette of standard colors, or specify a custom color. The color is applied to the label text for the state that is selected in the Select State section of the States component on the Design tab.

Horizontal Alignment — Horizontal alignment of label and icon pair with block

Left (default) | Center | Right

Set the alignment of the label and icon pair in the horizontal direction. The table lists the horizontal position of the label and icon pair when the X Offset is zero. A nonzero X Offset moves the label and icon pair from the position listed in the table.

Alignment	Position of the Label and Icon Pair
Left	The left edge of the label and icon pair is at the left edge of the block.
Center	The horizontal middle of the label and icon pair is at the horizontal middle of the block.
Right	The right edge of the label and icon pair is at the right edge of the block.

Vertical Alignment — Vertical alignment of label and icon pair with block

Center (default) | Bottom | Top

Set the alignment of the label and icon pair in the vertical direction. The table lists the vertical position of the label and icon pair when the Y Offset is zero. A nonzero Y Offset moves the label and icon pair from the position listed in the table.

Alignment	Position of the Label and Icon Pair
Top	The top edge of the label and icon pair is at the top edge of the block.
Center	The vertical middle of the label and icon pair is at the vertical middle of the block.
Bottom	The bottom edge of the label and icon pair is at the bottom edge of the block.

Icon and Label X Offset — Horizontal offset of icon and label pair from block

0 (default) | scalar

How the X Offset is measured depends on the value of the Horizontal Alignment. The table lists how the offset is measured for each Horizontal Alignment value. Relative to the position when the offset is 0, an offset with a negative value moves the text left, and an offset with a positive value moves the text right.

Horizontal Alignment	Offset
Left	Specify the horizontal offset of the left edge of the label and icon pair from the left edge of the block as a ratio of the block width.
Center	Specify the horizontal offset of the horizontal middle of the label and icon pair from the horizontal middle of the block as a ratio of the block width.
Right	Specify the horizontal offset of the right edge of the label and icon pair from the right edge of the block as a ratio of the block width.

Icon and Label Y Offset — Vertical offset of icon and label pair from block

0 (default) | scalar

How the Y Offset is measured depends on the value of the Vertical Alignment. The table lists how the offset is measured for each Vertical Alignment value. Relative to the position of the text when the offset is 0, an offset with a negative value moves the text up, and an offset with a positive value moves the text down.

Horizontal Alignment	Offset
Top	Specify the vertical offset of the top edge of the label and icon pair from the top edge of the block as a ratio of the block width.
Center	Specify the vertical offset of the vertical middle of the label and icon pair from the vertical middle of the block as a ratio of the block width.
Bottom	Specify the vertical offset of the bottom edge of the label and icon pair from the bottom edge of the block as a ratio of the block width.

Icon Placement — Placement of icon relative to label

Left (default) | Top | Right | Bottom

Specify the placement of the icon relative to the label.

Note

Changing the placement of the icon moves the label, but does not change the offset or alignment of the label.

Icon Width — Icon width

scalar

Specify the icon width as a ratio of the font height of the label text.

Example: 0.5

Icon Height — Icon height

scalar

Specify the icon height as a ratio of the font height of the label text.

Example: 0.5

Lock Aspect Ratio — Option to maintain image aspect ratio

on (default) | off

Enable this option to maintain the aspect ratio when resizing the image using the Property Inspector.

Image X Offset — Horizontal offset of left edge of image from left edge of block

scalar

Specify the horizontal offset of the left edge of the image from the left edge of the block as a ratio of the block width. Relative to the position of the image when the offset is 0, an offset with a negative value moves the image left, and an offset with a positive value moves the image right.

Example: 1

Image Y Offset — Vertical offset of top edge of image from top edge of block

scalar

Specify the vertical offset of the top edge of the image from the top edge of the block as a ratio of the block height. Relative to the position of the image when the offset is 0, an offset with a negative value moves the image up, and a positive value moves the image down.

Example: 1

Image Width — Image width

scalar

Specify the image width as a ratio of the block width.

Example: 0.5

Image Height — Image height

scalar

Specify the image height as a ratio of the block height.

Example: 0.5

Background Image

Use Background Color — Option to specify solid background color for button

on (default) | off

You can provide a background image for the block or select a solid background color for the button. To select a solid background color for the button, select this parameter. To provide a background image for the block, clear this parameter.

Note

• The state images are not visible when you set a solid background color for the button. To make the state images visible, turn off Use Background Color.

• Changing the background color using the Format tab of the Simulink Toolstrip removes the background image and turns on the Use Background Color parameter.

Example: on

Color — Button background color

[r g b] vector

To select a solid background color for the button, enable the Use Background Color parameter. Then, choose a background color from the palette of standard colors, or specify a custom color.

Note

The state images are not visible when you set a solid background color. To make the state images visible, in the Property Inspector, on the Design tab, in the Background Image component, turn off Use Background Color.

Tip

You can also specify the Background Color in the Format tab of the Simulink Toolstrip.

To specify the color of the block text, use the Font Color parameter.

Programmatic Use

Specify the BackgroundColor parameter for the block as a 1-by-3 [r g b] vector with values between 0 and 1 that is formatted as a string or a character vector.

Block Parameter: BackgroundColor

Type: character vector | string

Values: [r g b] vector

Opacity — Button background opacity

1 (default) | scalar

Specify the opacity of the solid background color as a scalar value from 0 to 1.

Example: 0.5

Corner Radius — Corner radius of area with button background color

scalar

Specify the corner radius of the area covered by the solid background color.

Example: 0.25

Foreground Image

X Offset — Horizontal offset of left edge of foreground image from left edge of block

scalar

Specify the horizontal offset of the left edge of the image from the left edge of the block as a ratio of the block width. Relative to the position of the image when the offset is 0, an offset with a negative value moves the image left, and an offset with a positive value moves the image right.

Example: 1

Y Offset — Vertical offset of top edge of foreground image from top edge of block

scalar

Specify the vertical offset of the top edge of the image from the top edge of the block as a ratio of the block height. Relative to the position of the image when the offset is 0, an offset with a negative value moves the image up, and a positive value moves the image down.

Example: 1

Width — Foreground image width

scalar

Specify the width of the foreground image as a ratio of the block width.

Example: 0.5

Height — Foreground image height

scalar

Specify the height of the foreground image as a ratio of the block height.

Example: 0.5

Lock Aspect Ratio — Option to maintain foreground image aspect ratio

on (default) | off

Select this parameter to maintain the aspect ratio when resizing the image using the Property Inspector.

Block Characteristics

Data Types
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

Tips

To design a button that changes the value of a variable or parameter in your model, use the Push Button block.

Extended Capabilities

C/C++ Code Generation

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

Dashboard blocks are ignored for code generation.

Version History

Introduced in R2017b

R2023b: Open panel in new window

Starting in R2023b, you can open a dashboard panel in a new window. To do so, select the panel and pause on the ellipsis that appears. In the action menu that expands, click the Open In New Window button .

You can minimize and restore the new window containing the panel separately from the model window. From the panel window, you can run, pause, stop, and step through the simulation. In the panel window, you can edit the panel and the blocks it contains.

To return the panel to the model canvas, in the panel window toolstrip, click Open in canvas .

For more information about opening a panel in a new window, see Open Panels in New Window.

R2023a: Persistent panels tab in Simulink Toolstrip

When you add a dashboard panel to a model, the Panels tab appears in the Simulink Toolstrip and shows options for managing and editing panels.

Previously, the Panels tab was only visible when a panel was selected. Starting in R2023a, the Panels tab stays visible when no panel is selected.

The Panels tab also contains these new options:

• You can add an empty panel.

• You can rename the selected panel.

• You can hide the selected panel.

R2023a: Callback Button blocks in Dashboard Library and Customizable Blocks Library have same customization

Starting in R2023a, the Callback Button block from the Dashboard library has the same customization options as the Callback Button block from the Customizable Blocks library.

R2022b: Undo and redo support for customizable dashboard blocks in panel

Starting in R2022b, you can undo and redo the changes you make to customizable dashboard blocks that are in a panel.

To undo or redo a change:

1. Click the panel or a block in the panel.

2. Press Ctrl+Z to undo the change, or press Ctrl+Y to redo the change.

Note

The keyboard shortcuts are based on Windows^®. On a Mac, press command (⌘) instead of Ctrl.

R2022b: Toolstrip support for panels

Starting in R2022b, you can use the Simulink Toolstrip to manage and edit panels and the dashboard blocks that they contain.

When you click a dashboard block in a panel, the toolstrip tab for the block appears. For example, when you click a Circular Gauge block, the Gauge tab appears in the toolstrip.

When you click a panel, the Panel tab appears in the toolstrip. The tab provides these options:

• Manage the visibility of panels in the model.

• Fit all unhidden panels within the current view.

• Collapse the selected panel.

• Customize the size and the contents of the panel.

• Set a custom background image for the selected panel.

• Add a new tab to the selected panel.

R2020b: Simulink Toolstrip support for dashboard blocks

Starting in R2020b, the Block tab in the Simulink Toolstrip turns into a block-specific tab when you select a block in your model that is from the Dashboard library in the Simulink library or from the Flight Instruments library in the Aerospace Blockset™ Flight Control Analysis library. From the toolstrip, you can connect, disconnect, and modify connections for the selected block. You can jump to the model element connected to the selected block, and you can add the selected block to a panel.

R2019a: Programmatically add and configure dashboard blocks

Starting in R2019a, you can use functions such as add_block and set_param to create and configure blocks from the Dashboard library in your model.