Knob

Tune parameter value with dial

• 

Libraries:
Simulink / Dashboard

Description

The Knob block tunes the value of the connected block parameter to during simulation. For example, you can connect the Knob block to a Gain block in your model and adjust its value during simulation. You can modify the range of the Knob block's scale to fit your data. Use the Knob block with other Dashboard blocks to create an interactive dashboard to control your model.

Connect Dashboard Blocks

Dashboard blocks do not use ports to connect to model elements. To connect a dashboard block, use connect mode. To enter connect mode on an unconnected block, pause on the block you want to connect and click the Connect button . To enter connect mode on a connected block, select the block, pause on the ellipsis that appears (…), and in the action menu that expands, click the Connect button.

To connect a control block to a parameter in your model or to change the connection of a control block, enter connect mode. Select the block to whose parameter you want to connect. From the list that appears, select the parameter to which you want to connect. Then, pause on the dashboard block and click the Done Connecting button .

The control block cannot connect to a parameter defined by a variable until you update the model diagram. To connect to a parameter defined by a variable or to modify the value of a variable that defines the value of a connected parameter when the simulation is not running, update the model diagram by pressing Ctrl+D.

You can connect to a parameter with a scalar value or to an element of a matrix or structure. For more information, see Connect Dashboard Blocks to Simulink Model.

You can also connect dashboard blocks to a Stateflow^® chart. For more information, see Connect Dashboard Blocks to Stateflow (Stateflow).

This animation shows how to connect the Knob block to your model.

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 Workspace or File. The parameter data is stored in a Simulink.SimulationData.Parameter object, accessible as an element in the exported Simulink.SimulationData.Dataset.

Examples

Change Gain Value Using Knob Block

You can use a Knob block to set the value of a parameter to one of several values during simulation. For example, in the model knobGain, a Knob block is connected to the Gain parameter of a Gain block. The Knob block is configured such that you can choose a gain value between 0 and 20.

Simulate the model. To change the gain value during simulation, turn the Knob block.

Extended 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

Interactively Simulate Vehicle Climate Control System

Use a dashboard of controls and indicators to interact with the simulation of an automobile climate control system.

• Open Model

Limitations

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

• You cannot use the Connection table in the Block Parameters dialog box 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 — Block parameter value to connect

parameter value connection options

Dashboard blocks do not use ports to connect to model elements. To connect dashboard blocks to parameter values in your model, use connect mode, the Simulink^® Toolstrip, or the Connection table in the Block Parameters dialog box. You can connect to a parameter with a scalar value, or to an element of a matrix. For information about connect mode and how to connect using the toolstrip, see Connect Dashboard Blocks to Simulink Model.

To connect a control block to a parameter with a scalar value or change the connection of a control block to a parameter with a scalar value using the Connection table:

1. Select the block.

2. To connect the block, in the Property Inspector, on the Parameters tab, click Connect. To change the connection of the block, click Change instead.

3. Select the block to whose parameter value you want to connect.

4. In the table, select the parameter to which you want to connect.

5. Click Apply.

The control block cannot connect to a parameter defined by a variable until you update the model diagram. To connect to a parameter defined by a variable or to modify the value of a variable that defines the value of a connected parameter when the simulation is not running, update the model diagram by pressing Ctrl+D.

You can also connect dashboard blocks to a Stateflow chart. For more information, see Connect Dashboard Blocks to Stateflow (Stateflow).

Programmatic Use

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

Block Parameter: Binding

Type: Simulink.HMI.ParamSourceInfo

Default: []

Scale Type — Type of scale

Linear (default) | Log

Type of scale displayed on the block. Linear specifies a linear scale, and Log specifies a logarithmic scale.

Programmatic Use

Block Parameter: ScaleType

Type: string or character vector

Values: 'Linear' | 'Log'

Default: 'Linear'

Minimum — Minimum tick mark value

0 (default) | scalar

Finite, real, double, scalar value specifying the minimum tick mark value for the scale. The minimum must be less than the value of the Maximum parameter.

Programmatic Use

To programmatically set the Minimum parameter, use a 1-by-3 vector containing values for the Minimum, Tick Interval, and Maximum parameters, in that order. To use the auto value for the Tick Interval, leave the Tick Interval position in the vector empty or specify -1.

Block Parameter: Limits

Type: 1x3 vector

Default: [0 -1 100]

Maximum — Maximum tick mark value

100 (default) | scalar

Finite, real, double, scalar value specifying the maximum tick mark value for the scale. The maximum must be greater than the value of the Minimum parameter.

Programmatic Use

To programmatically set the Maximum parameter, use a 1-by-3 vector containing values for the Minimum, Tick Interval, and Maximum parameters, in that order. To use the auto value for the Tick Interval, leave the Tick Interval position in the vector empty or specify -1.

Block Parameter: Limits

Type: 1x3 vector

Default: [0 -1 100]

Tick Interval — Interval between major tick marks

auto (default) | scalar

Finite, real, positive, whole, scalar value specifying the interval of major tick marks on the scale. When set to auto, the block automatically adjusts the tick interval based on the values of the Maximum and Minimum parameters.

Programmatic Use

To programmatically set the Tick Interval parameter, use a 1-by-3 vector containing values for the Minimum, Tick Interval, and Maximum parameters, in that order. To use the auto value for the Tick Interval, leave the Tick Interval position in the vector empty or specify -1.

Block Parameter: Limits

Type: 1x3 vector

Default: [0 -1 100]

Label — Block label position

Top (default) | Bottom | Hide

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

Default: 'Top'

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 R2015a

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.

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.

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: 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.