Combo Box

Select parameter value from drop-down menu

• 

Libraries:
Simulink / Dashboard

Description

The Combo Box block lets you set the value of a parameter to one of several values. You can define each selectable value and its label through the Combo Box block parameters. Use the Combo Box block with other Dashboard blocks to build an interactive dashboard of controls and indicators for your model.

Double-clicking the Combo Box block does not open its dialog box during simulation and when the block is selected. To edit the block's parameters, you can use the Property Inspector, or you can right-click the block and select Block Parameters from the context menu.

Connect Dashboard Blocks

Dashboard blocks do not use ports to connect to model elements. To connect dashboard blocks to variables and block parameters, use connect mode. Connect mode facilitates the process of connecting dashboard blocks in your model, especially when you want to connect multiple blocks at once. To connect a single dashboard block, you can also use the Connection table in the block dialog box.

Tip

You can modify dashboard block connections in your model during normal and accelerator mode simulations.

Note

Dashboard blocks cannot connect to variables until you update the model diagram. To connect dashboard blocks to variables or modify variable values between opening your model and running a simulation, update the model diagram using Ctrl+D.

To enter connect mode, in the canvas, select the dashboard block to connect. On the Simulink^® Toolstrip, a tab named after the type of the selected block appears. On the block tab, click Connect. In connect mode, when you select one or more blocks, a list of parameters and variables available for connection appears. Select a variable or parameter from the list to connect to the selected dashboard block.

When the value of the selected variable or block parameter is nonscalar, use the text box at the bottom of the Connection table to specify the element you want to connect to the dashboard block. To connect to an element of a vector, matrix, or array, specify the element index, for example, 3 or (1,3). To connect to an element in a bus or structure, specify the element in the context of the bus or structure hierarchy by using dots to indicate different levels in the hierarchy, and omit the top level. For example, specify a.b to connect to scalar element b of the structure or bus a nested inside the selected composite variable or parameter.

To connect another dashboard block, pause on another dashboard block and click the Connect button above it. Then, make a selection of signals and blocks in your model and choose a model element to connect.

When you finish connecting the dashboard blocks in your model, on the block tab, click Done Connecting.

Tip

You can hide the message shown on unconnected blocks using the set_param function with the ShowInitialText block parameter. The message also disappears when you connect the block.

Parameter Logging

Tunable parameters connected to dashboard blocks are logged to the Simulation Data Inspector, where you can view the parameter values along with logged signal data. You can access logged parameter data in the MATLAB^® workspace by exporting the parameter data from the Simulation Data Inspector by using the UI or the Simulink.sdi.exportRun function. For more information about exporting data using the Simulation Data Inspector UI, see Export Data to the Workspace or a File. The parameter data is stored in a Simulink.SimulationData.Parameter object, accessible as an element in the exported Simulink.SimulationData.Dataset.

Examples

Interactively Simulate a Thermal Model of a House

Use Dashboard blocks to configure and then interactively simulate a thermal model of a house.

Open Model

Limitations

• Except for the Dashboard Scope block and the Display block, dashboard blocks can only connect to real scalar signals.

• The toolstrip does not support blocks that are inside a panel.

• You cannot use the Connection table in the block dialog to connect a dashboard block to a block that is commented out. When you connect a dashboard block to a commented block using connect mode, the dashboard block does not display the connected value until the you uncomment the block.

• Dashboard blocks cannot connect to model elements inside referenced models.

• When you simulate a model hierarchy, dashboard blocks inside referenced models do not update.

• Dashboard blocks do not support rapid accelerator simulation.

• When you connect a dashboard block to a variable or parameter during simulation, the data for that variable or parameter is not logged to the Simulation Data Inspector. To log variable and parameter data to the Simulation Data Inspector, connect the dashboard block to the variable or parameter prior to simulation.

• When you simulate a model in external mode with the Default parameter behavior set to Inlined, dashboard blocks can appear to change parameter and variable values. However, the change does not propagate to the simulation. For example, Gain blocks display changes made to the Gain parameter using the dashboard blocks, but the Gain value used in the simulation does not change.

Parameters

Connection

Connection — Select a variable or block parameter to connect

variable and parameter connection options

Select the variable or block parameter to control using the Connection table. To connect the block to a signal:

1. Make a selection in the model that includes one or more blocks.

2. Select the variable or parameter you want to connect.

   When the value of the selected variable or block parameter is nonscalar, use the text box at the bottom of the Connection table to specify the element you want to connect to the dashboard block. To connect to an element of a vector, matrix, or array, specify the element index, for example, 3 or (1,3). To connect to an element in a bus or structure, specify the element in the context of the bus or structure hierarchy by using dots to indicate different levels in the hierarchy, and omit the top level. For example, specify a.b to connect to scalar element b of the structure or bus a nested inside the selected composite variable or parameter.

3. Click Apply.

To facilitate understanding and debugging your model, you can connect Dashboard blocks to variables and parameters in your model during simulation.

Note

To see workspace variables in the connection table, update the model diagram using Ctrl+D.

Programmatic Use

To programmatically connect a dashboard block to a tunable parameter or a variable, use a Simulink.HMI.ParamSourceInfo object. The Simulink.HMI.ParamSourceInfo object contains four properties. Some of the properties apply to connecting dashboard blocks to parameters, and some apply to connecting dashboard blocks to variables. Not all fields have a value for a connection because a given dashboard block connects to either a parameter or a variable.

Block Parameter: Binding

Type: Simulink.HMI.ParamSourceInfo

Default: []

Main

Enumerated Data Type — Specify state values and labels using an enumerated data type

off (default) | on

You can use an enumerated data type that pairs a numeric value with each enumeration to configure the state values and labels for the block. To specify the states for the block using an enumerated data type, first select the Enumerated Data Type option. Then, specify the name of the enumerated data type in the text box. The definition for the specified enumerated data type must be saved on the MATLAB path or in the base workspace.

Example: myEnumType

Programmatic Use

To programmatically specify the state labels and values for the block using an enumerated data type, specify 'on' for the UseEnumeratedDataType parameter and the name of the enumerated data type for the EnumeratedDataType parameter.

Block Parameter: UseEnumeratedDataType

Type: string or character array

Values: 'on' | 'off'

Default: 'off'

Block Parameter: EnumeratedDataType

Type: string or character array

Default: ''

Label — Block label position

Hide (default) | Bottom | Top

Position of the block label. When the block is connected to an element in the model, the label is the name of the connected element.

Programmatic Use

Block Parameter: LabelPosition

Type: character vector

Values: 'Hide' | 'Bottom' | 'Top'

Default: 'Hide'

States — Set of states to select for connected parameter

scalar and character vector

Set of states from which to select a value for the connected parameter. Each State consists of a State Value and a State Label.

• State Value — Value assigned to the connected variable or parameter when you select the state with the corresponding Label.

• State Label — Label for each state. You can use the Label to display the value the connected parameter takes when the switch is positioned at the bottom, or you can enter a descriptive text label.

Click the + button to add additional States.

The default configuration for the block includes these States.

State Value	State Label
0	Label1
1	Label2
2	Label3

Programmatic Use

To programmatically configure the States for a block, use an array of structures containing the fields Value and Label. Include a structure in the array for each state you want to configure on the block.

state1.Value = 1;
state1.Label = 'State 1';
state2.Value = 2;
state2.Label = 'State 2';
radioStates = [state1 state2];

Block Parameter: States

Type: structure

Default: 3x1 structure array

Format

Opacity — Block background opacity

1 (default) | scalar

Block background opacity, specified as a scalar value between 0 and 1.

Example: 0.5

Programmatic Use

Block Parameter: Opacity

Type: scalar

Default: 1

Foreground Color — Block foreground color

[r g b] vector

Block foreground color, including the text. You can select a color from a palette of standard colors or specify a custom color.

Programmatic Use

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

Block Parameter: ForegroundColor

Type: character vector | string

Values: [r g b] vector

Background Color — Block background color

[r g b] vector

Block background color. You can select a color from a palette of standard colors or specify a custom color.

Programmatic Use

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

Block Parameter: BackgroundColor

Type: character vector | string

Values: [r g b] vector

Block Characteristics

Data Types	double | half | integer | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
Zero-Crossing Detection	no

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

R2021a: Tune matrix and structure elements using dashboard blocks

Starting in R2021a, you can connect a block from the Dashboard library to a scalar element of a matrix or structure that defines the value of a tunable block parameter. When you connect a dashboard block to a tunable parameter, you first select one or more blocks. Then, in a dialog box, you select the parameter to which you want to connect. When you select a parameter that has a nonscalar value, specify the element you want to tune using the text box in the dialog box.

R2020b: Background Color, Foreground Color, and Opacity properties added for several dashboard blocks

Starting in R2020b, you can specify a background color, a foreground color, and opacity for these blocks from the Dashboard library:

• Check Box

• Combo Box

• Edit

• Push Button

• Radio Button

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.

R2019b: Enhanced enumerated data type support for the Rotary Switch block and Combo Box block

Starting in R2019b, you can use an enumeration class to configure the values and labels for the states of a Rotary Switch block and a Combo Box block.

To configure the States for a Rotary Switch or Combo Box block with an enumerated data type, select Enumerated Data Type. In the text box, enter the name of the enumeration class you want to use.

When you use an enumeration class to configure the states of the block, you cannot manually edit, add, or remove states from the States table.

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.