In Bus Element

Select input from external port

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Libraries:
Simulink / Ports & Subsystems
Simulink / Sources
HDL Coder / Ports & Subsystems
HDL Coder / Sources

Alternative Configurations of In Bus Element Block:
Bus Element In

Description

The In Bus Element block selects input from an external port that receives a bus, signal, or message.

When the port receives a bus, the In Bus Element block combines the functionality of an Inport block and a Bus Selector block. To select multiple elements from the bus, use multiple In Bus Element blocks. All In Bus Element blocks that correspond with the same port share a dialog box.

For interfaces that include buses composed of many bus elements, In Bus Element blocks:

• Reduce signal line complexity and clutter in a block diagram.

• Allow you to more easily make incremental changes to the interface.

• Allow access to a bus element closer to the point of usage, avoiding the use of a Bus Selector and Goto block configuration.

To convert an interface to use In Bus Element blocks, see Simplify Subsystem and Model Interfaces with Bus Element Ports.

The In Bus Element block does not support mixing message and signal elements as outputs.

Examples

Create Input Bus Element Port

In a model component, each input bus element port is represented by one or more In Bus Element blocks.

Open the example model named CreateInputBusElementPort.

How you add an input bus element port depends on whether you are working in the model component or its parent.

To add an input bus element port to the currently open subsystem or model, add an In Bus Element block to the subsystem or the top level of the model. For example, double-click the canvas and start typing the block name. Then, select the In Bus Element block.

To add an input bus element port to a Subsystem or Model block in the current component, click the edge of the block and select Create in bus port. For example, add an input bus element port to the Subsystem block.

To open the subsystem, double-click the Subsystem block.

The subsystem contains a default In Bus Element block that corresponds to the input port you created on the Subsystem block. The block label uses default values for its two interactive text fields: the port name (InBus) and the bus element (signal1).

To create another input bus element port from inside a model component, hold Ctrl while you drag an existing In Bus Element block to a new location. Upon releasing the pointer, click Create New Port.

An In Bus Element block with a unique port name appears.

In this example, the new port is named InBus1.

To edit the port name, click the port name in the block label. Then, enter a new name.

Alternatively, set the Port name block parameter to the desired name for the port.

When multiple blocks are associated with the same port and you change the name of the port, all blocks that share the port update to reflect the new port name.

Select Entire Input from Bus Element Port

The input to a bus element port can be a bus, signal, or message. To pass the entire input through an In Bus Element block instead of selecting an element of an input bus, remove the part of the block label that represents an element.

Open and compile the SelectTopLevelInput model. To compile the model, on the Modeling tab of the Simulink Toolstrip, click Update Model or Run. Compiling the model updates the line styles, which you can use to visually identify buses.

The Subsystem block has bus element ports named InBus and Constant. One of the ports connects to a bus. The other port connects to a signal.

Open the subsystem, which contains one In Bus Element block per port.

The top In Bus Element block selects the element named chirp from the port named InBus.

The bottom In Bus Element block selects the entire input from the port named Constant. The entire input is a constant signal.

To select the entire input from the port named InBus, delete the second text field from the block label. For example, click chirp to edit the text field.

Then, delete chirp. To commit the change, click elsewhere on the canvas.

Update the line styles by compiling the model.

The In Bus Element block passes the entire input into the subsystem. In this case, the entire input is the top-level bus for the port.

When you select the entire input from an In Bus Element block, you can propagate the line labels. In the Simulink Toolstrip, on the Debug tab, click Information Overlays. Then, select Propagated Signal Labels.

The In Bus Element blocks pass the bus named nonconstant and the signal named constant into the subsystem.

To pass a top-level bus into a referenced model using an In Bus Element block, you must perform one of these actions using the In Bus Element block:

• Define the bus with a Simulink.Bus object.

• Specify at least one leaf element of the bus with or without another In Bus Element block.

Select Elements of Subsystem Input Port

To select elements of an input bus element port of a subsystem, use an In Bus Element block for each element that you want to select.

Open and compile the example model named SelectInputBusElements. To compile the model, on the Modeling tab of the Simulink Toolstrip, click Update Model or Run. Compiling the model updates the line styles, which you can use to visually identify buses.

A Bus Creator block creates a virtual bus that contains two elements: a nested bus named nonconstant and a signal named constant. The nonconstant bus contains two signals named sine and chirp. The top-level bus connects to the input port of the Subsystem block.

To open the subsystem, double-click the Subsystem block.

The subsystem contains an In Bus Element block that corresponds to the input port. The block label indicates that the block selects the signal named constant from the input port.

To change the element that the block selects, edit the second text field in the block label. When the second text field is empty, a menu provides the elements of the port along with the previously selected element.

When the list of input elements is long, filter the list of elements by starting to type the name of the element you want to select.

For this example, type chirp.

The list provides the text you type as an option. However, the top-level input bus does not contain a signal named chirp. The nested bus named nonconstant contains the signal named chirp. Therefore, select the option named nonconstant.chirp. Each dot in the label follows the name of a bus in the input bus hierarchy.

Open the Property Inspector. Then, select the In Bus Element block. Alternatively, double-click the block to open a dialog box.

The element that the block selects is highlighted. The elements that an In Bus Element block does not select are gray and italicized.

To add blocks for additional input elements, click an element name or hold Ctrl as you click multiple element names. Then, click Add blocks for selected signals.

Corresponding In Bus Element blocks appear in the block diagram.

Multiple In Bus Element blocks can select the same element. For example, add another block that selects the element named constant.

The duplicate block is highlighted.

Define Interface Without Bus Object

To specify the elements of an input bus element port at an interface, you can:

• Add elements to the interface with or without adding blocks to the block diagram.

• Define the bus hierarchy with a Simulink.Bus object.

Note

For you to specify a Simulink.Bus object as the data type of an input bus at a bus element port, an In Bus Element block must select the bus or an element of the bus.

This example shows how to define an input bus element port at an interface without a Simulink.Bus object.

In a blank model or subsystem, add an In Bus Element block.

Open the Property Inspector. Then, select the In Bus Element block. Alternatively, double-click the block to open a dialog box.

To add an element to the port with a block, select the element that you want to contain the new element. Then, click .

The new element is nested under the previously selected element. In the block diagram, a block that selects the new element appears.

To add an element without a block, in the Property Inspector or dialog box, select the element that you want to contain a new element. Then, click the button arrow, and select Add element without block.

The new element is nested under the previously selected element in the Property Inspector or dialog box. The block diagram is unchanged.

By adding elements without adding blocks, you can define the entire bus hierarchy with only one In Bus Element block and without a Simulink.Bus object.

Optionally:

• Add more elements with or without blocks.

• Rename elements by double-clicking their names and entering new names.

• Reorder elements by dragging them to new locations.

• Specify element properties by pausing on their names, then clicking the pencil button that appears. For more information, see Attributes.

Defining the properties of elements at an interface is useful when you create a file for reuse. The interface definition determines the input that a referenced subsystem or model supports. The hierarchy and properties of the input bus must match the definition at the corresponding port.

Suppose you add elements without blocks then decide that you want In Bus Element blocks that select them. To add blocks for input elements, click an element name or hold Ctrl as you click multiple element names. Then, click .

Corresponding In Bus Element blocks appear in the block diagram.

Remove Invalid Elements and Related Blocks

An In Bus Element block can expect elements that are not available at the corresponding input port.

To remove the invalid elements and all In Bus Element blocks that select them, in the Property Inspector or dialog box:

1. Select the invalid elements to remove.

   For a subsystem interface, when an element is not available in the input bus, the element name is red. When you pause on the element name, a tooltip indicates that the element is not in the input bus.

2. Click .

For example, suppose you have a subsystem interface that receives a bus named InBus. An element named pulse has been removed from the input bus. However, at least one In Bus Element block selects the element.

To remove the blocks that select the invalid element, click the element name. Then, click .

The operation removes the invalid element and corresponding block.

When you select an element that is available at the input port of a subsystem, and then click , you remove all In Bus Element blocks that select the element. The element remains in the list because it is part of the input bus.

Find Duplicate In Bus Element Blocks

When multiple In Bus Element blocks select the same element, selecting one of the blocks highlights the other blocks that select the same element.

Open the ModelingControllerStandalone model.

Select one of the In Bus Element blocks labeled sensor.x1.

The block diagram highlights the other In Bus Element block labeled sensor.x1, indicating that the block is a duplicate of the selected In Bus Element block.

Suppose you have a more complicated controller model that uses more than two In Bus Element blocks that select sensor.x1 from the input port.

To find duplicate blocks when the block diagram is complicated, select the block, pause on the ellipsis, and in the action bar, click Related Blocks.

When multiple blocks correspond to the selected block, a list of related blocks opens. You can filter the list of related blocks by entering a search term in the text box. Clicking a related block in the list selects the block in the block diagram.

Customize Appearance of In Bus Element and Out Bus Element Blocks

Use compact labels and block colors to customize the appearance of In Bus Element and Out Bus Element blocks.

Open the example model named BusElementPortBlocks.

The model contains:

• In Bus Element blocks that represent two unique bus element ports named Inbus and pulse

• Out Bus Element blocks that represent a bus element port named OutBus

To reduce the size of the block labels, display only the leaf element names. Select an In Bus Element or Out Bus Element block, pause on the ellipsis, and in the action bar, click Compact Notation.

All In Bus Element and Out Bus Element blocks in the block diagram display shortened block labels that use only the leaf element name.

To show the full block label, in the action bar, you can click Expanded Notation. For this example, keep the compact block labels.

Block colors can help differentiate unique ports when the block labels are compact.

Open the Property Inspector. Then, select an In Bus Element block that corresponds with the port named InBus. For example, select the block labeled constant. Alternatively, double-click the block to open a dialog box.

In the Property Inspector or dialog box, select InBus. Then, click Set color and select a color from the menu.

The blocks related to the port use the chosen color.

To identify the blocks that select the nested bus named nonconstant or its elements, select nonconstant. Then, click Set color and select a different color from the menu.

The blocks related to the nested bus use the chosen color.

Extended Examples

Explore Simulink Bus Capabilities

Work with buses in components, use bus ports at component interfaces, and perform common bus workflows faster.

Open Model

Load Input Data for a Bus Using In Bus Element Blocks

Load input data for a bus using In Bus Element blocks.

Open Live Script

Programmatically Create Bus Element Ports

Add blocks for bus element ports and specify element attributes using MATLAB^® functions.

Open Live Script

Ports

Output

Port_1 — Selected input from external port

scalar | vector | matrix | array | bus

Select a bus, signal, or message from the corresponding external input port of the parent subsystem or model.

While you can select bus elements, you cannot select elements of arrays of buses.

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

Parameters

To interactively edit the parameters of the block, the corresponding port, and the elements at the port, double-click the block or open the Property Inspector and select the block.

Port name — Name of input port

InBus (default) | port name

Specify a port name that is not already in use by another block or port. The name appears on the parent Subsystem or Model block. The name also appears next to the block. Multiple blocks can access the same port.

Programmatic Use

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

Parameter:	PortName
Values:	'InBus' (default) | port name in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/PortBlock','PortName','myBus')

Port number — Position of port on parent block

1 (default) | real integer

Specify the order in which the port that corresponds to the block appears on the parent Subsystem or Model block.

• If you add a block that creates another port, the port number is the next available number.

• Deleting all blocks associated with a port deletes the port. Other ports are renumbered so that they are sequential and do not skip any numbers.

• Specifying a port number that exceeds the number of ports creates a port for that number and for any skipped sequential numbers.

Programmatic Use

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

Parameter:	Port
Values:	'1' (default) | real integer in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/PortBlock','Port','5')

Set color — Block background color

Black (default) | White | Red | Green | Blue | Cyan | Magenta | Yellow | Gray | Light Blue | Orange | Dark Green | More Colors

Specify the block background color. This specification sets the color of blocks associated with selected elements, or of all blocks associated with the port if you do not select any elements.

Programmatic Use

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

Parameter:	BackgroundColor
Values:	'black' (default) | 'white | 'red' | 'green' | 'blue' | 'cyan' | 'magenta' | 'yellow' | 'gray' | 'lightBlue' | 'orange' | 'darkGreen' | '[r,g,b]' where r, g, and b, are the red, green, blue values of the color in the range 0.0 to 1.0

Example: set_param('mymodel/Subsystem1/PortBlock','BackgroundColor','magenta')

Filter — Filter for displayed bus elements

no default

Specify a search term to use for filtering a long list of bus elements. Do not enclose the search term in quotation marks. The filter does a partial string search and supports regular expressions. To use a regular expression character as a literal, include an escape character (\). For example, to use a question mark, type sig\?1.

Attributes

To specify attributes, such as data type, pause on the name of a bus, signal, or message. Then, click the pencil button that appears.

When you specify attributes, they appear next to the name of the bus, signal, or message. Click an attribute summary to edit the attributes of the bus, signal, or message.

Data type — Data type

Inherit: auto (default) | double | single | half | int8 | uint8 | int16 | uint16 | ...

The data type of a bus, signal, or message can be inherited, specified directly, or expressed as a data type object such as a Simulink.NumericType object.

You can specify any of these options:

• Inherited data type

• Built-in Simulink^® data type — For example, specify single or uint8. See Data Types Supported by Simulink.

• Fixed-point data type — Use the fixdt function. For example, specify fixdt(1,16,0).

• Enumerated data type — Use the name of the type preceded by Enum:. For example, specify Enum: myEnumType.

• Bus data type — Use the name of the Simulink.Bus object preceded by Bus:. For example, specify Bus: myBusObject.

• Value type — Use the name of the Simulink.ValueType object preceded by ValueType:. For example, specify ValueType: windVelocity.

• Custom data type — Use a MATLAB expression that specifies the type. For example, you can specify a Simulink.NumericType object whose DataTypeMode property is set to a value other than 'Fixed-point: unspecified scaling'.

When you specify a Simulink.ValueType object as the data type, some parameters of the element are ignored. For example, the Min, Max, and Unit parameters are ignored. The software uses the corresponding properties of the Simulink.ValueType object. For example, suppose you set Unit to ft/s for an element. When the Data type of the element specifies a ValueType object that has m/s as its unit, the element uses m/s instead of ft/s.

When you specify a Simulink.Bus object as the data type, some parameters of the element are reset to their default values. For example, the Min, Max, and Unit parameters are reset. The software uses the corresponding properties of the Simulink.BusElement objects in the Simulink.Bus object instead.

Tips

When you specify a bus using a Simulink.Bus object or a Simulink.ValueType object with a Simulink.Bus object data type, the Property Inspector and block dialog box display the elements defined by the corresponding Simulink.BusElement objects.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	OutDataTypeStr
Values:	'Inherit: auto' (default) | 'double' | 'single' | 'half' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'boolean' | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | 'string' | 'Enum: <class name>' | 'Bus: <object name>' | 'ValueType: <object name>' | '<data type expression>'

Example: set_param('mymodel/Subsystem1/myBus.signal1','OutDataTypeStr','int32')

Bus virtuality — Virtual or nonvirtual bus

inherit (default) | virtual | nonvirtual

Specify whether to inherit the bus virtuality or define the bus as virtual or nonvirtual. For more information, see Composite Interface Guidelines.

This parameter determines whether the blocks inherit or define the bus virtuality. If the blocks define the bus virtuality and the virtuality of the input bus does not match, compiling the model produces an error.

Dependencies

To enable this parameter, Data type must resolve to a Simulink.Bus object. For example, set Data type to a Simulink.Bus object or a Simulink.ValueType object that specifies a Simulink.Bus object as its data type.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	BusVirtuality
Values:	'inherit' (default) | 'virtual' | 'nonvirtual'

Example: set_param('mymodel/Subsystem1/myBus.nestedBus','BusVirtuality','nonvirtual')

Data mode — Data mode of input element

inherit (default) | signal | message

Specify the data mode of the input element.

• inherit — Input element inherits its data mode.

• signal — Input element must be a signal or a bus that contains signals.

• message — Input element must be a message or a bus that contains messages.

When you choose message as the data mode of a message or bus, an envelope button appears next to the message or bus. Use the envelope button to specify custom queue properties.

Tips

To specify different custom queue properties for each message in a bus, set the Data mode parameter for each message instead of the bus.

Dependencies

To enable this parameter, the block must be at the top level of a model.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	DataMode
Values:	'inherit' (default) | 'signal' | 'message'

Example: set_param('mymodel/InBus','DataMode','signal')

Dimensions — Signal dimensions

-1 (default) | integer | 1-by-2 vector of integers

Specify the dimensions of a signal.

• -1 — The signal can have any dimensions.

• N — The signal must be a vector of size N.

• [R C] — The signal must be a matrix having R rows and C columns.

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to 1. The software uses the dimensions specified by the Simulink.BusElement objects in the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the dimensions specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	PortDimensions
Values:	'-1' (default) | integer in quotes | 1-by-2 vector of integers in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/myBus.signal1','PortDimensions','[1 3]')

Dims mode — Option to allow only variable-size or fixed-size signals

Inherit (default) | Fixed | Variable

Specify the type of signals allowed.

• Inherit — Allow variable-size and fixed-size signals.

• Variable — Allow only variable-size signals.

• Fixed — Allow only fixed-size signals. Do not allow variable-size signals.

When the signal is variable-sized, the Dimensions parameter specifies the maximum dimensions of the signal.

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to Inherit. The software uses the dimensions modes specified by the Simulink.BusElement objects in the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the dimensions mode specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	VarSizeSig
Values:	'Inherit' (default) | 'No' | 'Yes'

Example: set_param('mymodel/Subsystem1/myBus.signal1','VarSizeSig','No')

Unit — Physical unit

inherit (default) | unit supported by Simulink software

Specify the physical unit of the signal. For a list of supported units, in the MATLAB Command Window, enter showunitslist.

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to inherit. The software uses the units specified by the Simulink.BusElement objects in the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the unit specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	Unit
Values:	'inherit' (default) | unit supported by Simulink software in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/myBus.signal1','Unit','m/s')

Complexity — Numeric type

auto (default) | real | complex

Specify the numeric type of the signal. To choose the numeric type of the signal, select auto. Otherwise, choose a real or complex signal type.

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to auto. The software uses the complexity specified by the Simulink.BusElement objects in the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the complexity specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	SignalType
Values:	'auto' (default) | 'real' | 'complex'

Example: set_param('mymodel/Subsystem1/myBus.signal1','SignalType','real')

Minimum — Minimum value

[] (default) | scalar

Lower value of the range that the software checks.

This number must be a finite real double scalar value.

The software uses this value to perform:

• Simulation range checking. For more information, see Specify Signal Ranges.

• Automatic scaling of fixed-point data types.

• Optimization of the code that you generate from the model. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. For more information, see Optimize using the specified minimum and maximum values (Embedded Coder).

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to []. The software uses the minimum values specified by the Simulink.BusElement objects in the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the minimum value specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	OutMin
Values:	'[]' (default) | scalar in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/myBus.signal1','OutMin','0')

Maximum — Maximum value

[] (default) | scalar

Upper value of the range that the software checks.

This number must be a finite real double scalar value.

The software uses this value to perform:

• Simulation range checking. For more information, see Specify Signal Ranges.

• Automatic scaling of fixed-point data types.

• Optimization of the code that you generate from the model. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. For more information, see Optimize using the specified minimum and maximum values (Embedded Coder).

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to []. The software uses the maximum values specified by the Simulink.BusElement objects in the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the maximum value specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	OutMax
Values:	'[]' (default) | scalar in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/myBus.signal1','OutMax','2')

Description — Description of bus, signal, or message

no default

Use the description to document information about the bus, signal, or message, such as where it is used. This information does not affect processing.

Dependencies

• When Data type specifies a Simulink.Bus object, the software sets this parameter to '' (empty). The software uses the description specified by the Simulink.Bus object.

• When Data type specifies a Simulink.ValueType object, the software ignores the value of this parameter. The software uses the description specified by the Simulink.ValueType object instead.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	Description
Values:	'' (default) | description in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/myBus.signal1','Description','This signal is used by...')

Execution Attributes

To specify execution attributes, such as sample time, pause on the name of a bus, signal, or message. Then, click Specify execution attributes .

Sample time — Sample time

-1 (default) | scalar

Specify the discrete interval between sample time hits or specify another type of sample time, such as continuous (0) or inherited (-1). For more options, see Types of Sample Time.

By default, the signal inherits its sample time.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	SampleTime
Values:	'-1' (default) | scalar in quotes
Data Types:	char | string

Example: set_param('mymodel/Subsystem1/InBus.signal1','SampleTime','2')

Events — Option to trigger model partition based on flow of data into port

cell array of event trigger objects

In a rate-based system, you can configure an input port in the top model or on a model reference interface to trigger the execution of one or more model partitions in response to the flow of data into the port. The parameter stores the event triggers associated with the port. Each event trigger maps an input event to the name of the schedule event it triggers. The schedule for the model specifies the partition to execute in response to the schedule event and the priority of execution.

The table summarizes the event triggers you can configure. You can configure an input port with one event trigger for each input event.

Input Event	Input Event Description	Event Trigger Object
Input write	Value for input port updates.	simulink.event.InputWrite
Input write timeout	Input port value does not update within a specified amount of time.	simulink.event.InputWriteTimeout
Input write lost	Input port value update overwrites unprocessed data.	simulink.event.InputWriteLost

To configure the schedule for your model, use the Schedule Editor.

When you configure input events on a bus port, where you specify the event triggers depends on the virtuality of the bus.

• For a virtual bus, specify event triggers on leaf elements of the bus. Specifying input events on the virtual bus itself is not supported.

• For a nonvirtual bus, specify event triggers on the bus. Specifying input events on elements of a nonvirtual bus is not supported.

In Bus Element blocks must select each element with event triggers.

Dependencies

To enable this parameter, the block must be at the top level of a model.

Programmatic Use

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

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	EventTriggers
Values:	[] (default) | 1-by-1 cell array | 2-by-1 cell array | 3-by-1 cell array

Example: set_param('mymodel/PortBlock','EventTriggers',{inputWrite,writeTimeout,writeLost})

Example: set_param('mymodel/InBus.signal1','EventTriggers',{inputWrite,writeTimeout,writeLost})

Queue Attributes

Queue attributes are visible only when the block is at the top level of a model and you set the Data mode parameter to message.

To specify queue attributes, click the envelope button next to the name of a bus or message.

Use default queue attributes — Default or custom queue specifications

on (default) | off

Use this parameter to select between default or custom queue specifications.

To use the default queue properties, leave the parameter selected. In this case, for each message bus element, a LIFO overwriting queue of capacity 1 is automatically inserted.

To use custom specifications, clear the parameter and configure the queue properties. Queue attributes are applicable if there is no storage block placed outside a component.

For more information, see Specify Queue Properties for Message Interface.

Dependencies

To enable this parameter for an element, set the Data mode of the element to message.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	MessageQueueUseDefaultAttributes
Values:	'on' (default) | 'off'

Example: set_param('mymodel/InBus.message1','MessageQueueUseDefaultAttributes','off')

Queue capacity — Message storage capacity

1 (default) | scalar

Specify the number of messages elements the queue can store.

Dependencies

To enable this parameter for an element, set the Data mode of the element to message.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	MessageQueueCapacity
Values:	'1' (default) | scalar in quotes
Data Types:	char | string

Example: set_param('mymodel/InBus.message1','MessageQueueCapacity','10')

Queue type — Choose FIFO or LIFO queue

LIFO (default) | FIFO

Choose one of these queue types:

• FIFO — First-in-first-out

• LIFO — Last-in-first-out

Dependencies

To enable this parameter for an element, set the Data mode of the element to message.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	MessageQueueType
Values:	'LIFO' (default) | 'FIFO'

Example: set_param('mymodel/InBus.message1','MessageQueueType','FIFO')

Queue overwriting — Queue message overwriting policy

on (default) | off

Select this parameter to choose between two queue overwriting policies.

• If you select the parameter, an incoming message element overwrites the oldest message if the queue is full.

• If you clear the parameter, the block does not accept new messages if the queue is full.

Dependencies

To enable this parameter for an element, set the Data mode of the element to message.

Programmatic Use

To programmatically set the attribute value for an element, use the set_param function, specifying the element as the block path of the model component with the element label.

Parameter:	MessageQueueOverwriting
Values:	'on' (default) | 'off'

Example: set_param('mymodel/InBus.message1','MessageQueueOverwriting','off')

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

Bus Element In — Select input from external port

The Bus Element In block differs from the In Bus Element block by name only.

Libraries:
Simulink / Signal Routing
HDL Coder / Signal Routing

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

HDL Code Generation

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

This block can be used to simplify subsystem bus interfaces when you use the block in subsystems that generate HDL code, but it is not included in the hardware implementation.

To learn more about using buses for HDL code generation, see Buses (HDL Coder) and Use Bus Signals to Improve Readability of Model and Generate HDL Code (HDL Coder).

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced in R2017a

R2023b: Specify elements without bus objects or additional blocks at subsystem interfaces

At both subsystem and model interfaces, you can specify the elements of an input bus without In Bus Element blocks to represent each element or a Simulink.Bus object to define the bus hierarchy. Previously, only In Bus Element blocks at model interfaces supported this functionality.

To add the elements, click the button arrow. Then, select Add element without block.

R2023a: Property Inspector supports In Bus Element blocks

The Property Inspector supports In Bus Element and Out Bus Element blocks.

R2023a: Diagnostic messages link to related In Bus Element blocks

Warning and error messages for In Bus Element and Out Bus Element blocks now link to the corresponding block in the block diagram, helping you quickly find the source of the warning or error. In previous releases, warning and error messages refer to a hidden block and do not provide a link.