Bus Creator

Create bus from input elements

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Libraries:
Simulink / Commonly Used Blocks
Simulink / Signal Routing
HDL Coder / Signal Routing

Description

The Bus Creator block combines a set of input elements into a bus. You can connect any element types to the input ports, including other buses. You can access elements in a bus by using a Bus Selector block.

Elements of a bus must have unique names. By default, each element of the bus inherits the name of the element connected to the Bus Creator block. If duplicate names are present, the Bus Creator block appends the port number to all input element names. For elements that do not have names, the Bus Creator block generates names in the form signaln, where n is the port number connected to the element. You can refer to elements by name when you search for their sources or select elements for connection to other blocks. For element naming guidelines, see Signal Names and Labels.

The Bus Creator block does not support mixing message and signal elements as inputs.

Examples

Group Signal Lines Within a Component

You can group signals into a virtual bus within a component by using Bus Creator blocks.

Open Model

Create Nonvirtual Buses Within a Component

You can use Bus Creator blocks to create nonvirtual buses within components.

Open Model

Simplify Bus Interfaces in Subsystems and Models

Convert a subsystem or model interface that uses Inport, Bus Selector, Bus Creator, and Outport blocks to use In Bus Element and Out Bus Element blocks.

Open Model

Explore Simulink Bus Capabilities

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

Open Model

Ports

Input

Port_1 — Input element to include in bus

scalar | vector | matrix | array | bus

The input ports accept the elements to include in the bus. The number of input ports is driven by the Number of inputs parameter.

You can specify variable-size input signals with upper bounds smaller than the upper bounds of the variable-size signals that the corresponding Bus Creator block input ports can accept. To configure the upper bounds of variable-size signals that Bus Creator block input ports accept, use a Simulink.BusElement object. For more information, see Simulink.BusElement. Variable-size input signals and variable-size signals that the corresponding Bus Creator block input ports accept must have the same dimensionality.

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

Output

Port_1 — Output virtual or nonvirtual bus

bus

The output bus is composed of the input elements. The Output as nonvirtual bus parameter specifies whether the output bus is a virtual or nonvirtual bus. For information about the types of buses, see Composite Interface Guidelines.

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

Parameters

Number of inputs — Number of input elements

2 (default) | integer

The number of input elements must be an integer greater than or equal to 2. Increasing the number of inputs adds empty input ports to the block. Before you simulate the model, make sure that an input element is connected to each input port.

When you modify the Number of inputs parameter, click Refresh to update the list of elements.

If all input ports are already connected, you can add an input port to the Bus Creator block by connecting another line to it.

Interactively adding a port updates the Number of inputs parameter and adds the new element to the list of elements in the bus.

Programmatic Use

Block Parameter: Inputs

Type: character vector

Values: integer greater than or equal to 2, comma-separated list of element names

Default: '2'

By default, the Inputs parameter specifies the number of inputs. When you use it to specify the names of elements in the bus, the number of inputs matches the number of element names you specify.

Elements in the bus — List of input elements

list of element names

The list of input elements includes all elements that enter the block, including the elements of nested buses. An arrow next to an element indicates that an input element is a bus. To display the contents of that bus, click the arrow.

To highlight the source of an element that enters the block, select the element in the list and click Find.

If you change an element name while the dialog box is open, click Refresh to update the name in the list.

To rearrange the elements in the output bus, use the Up and Down buttons. You can select multiple top-level adjacent elements in the Elements in the bus list to reorder or remove.

To add or remove input elements, click Add or Remove, respectively. Then, update the block icon by clicking Apply or OK. Before you simulate the model, make sure that an input element is connected to each input port.

Programmatic Use

Block Parameter: Inputs

Type: character vector

Values: integer greater than or equal to 2, comma-separated list of element names

Default: '2'

By default, the Inputs parameter specifies the number of inputs. When you use it to specify the names of elements in the bus, the number of inputs matches the number of element names you specify.

Filter by name — Search term for filtering displayed input elements

text

To filter the displayed input elements, enter a search term. The filter does a partial-string search. Do not enclose the search term in quotation marks.

To access the filtering options, click the Show filtering options button to the right of the Filter by name box.

Enable regular expression — Option to filter displayed input elements by regular expression

off (default) | on

Select this parameter to filter the displayed input elements with either regular expressions or partial search strings. By default, you can filter the displayed input elements with only partial search strings.

Regular expressions let you filter based on whether the input elements match a pattern. For example, enter t$ in the Filter by name box to display all elements whose names end with a lowercase t (and their immediate parents). For more informations, see Regular Expressions.

Dependencies

To access this parameter, click the Show filtering options button to the right of the Filter by name box.

Show filtered results as a flat list — Option to display filtered results as a flat list

off (default) | on

Select this parameter to display filtered results as a flat list that uses dot notation to reflect the bus hierarchy. By default, the filtered results appear in a hierarchical tree.

Dependencies

To access this parameter, click the Show filtering options button to the right of the Filter by name box.

Output data type — Data type of output bus

'Inherit: auto' (default) | 'Bus: <object name>' | <data type expression>

Specify the data type of the output bus.

If you select Bus: <object name>, replace <object name> with the name of a Simulink.Bus object. The Bus object must be accessible when you edit the model.

To define a Bus object using the Type Editor, click the Show data type assistant button , set Mode to Bus object, and then click the Edit button.

If you select <data type expression>, specify an expression that evaluates to a Bus object.

Programmatic Use

Block Parameter: OutDataTypeStr

Type: character vector

Values: 'Inherit: auto' | 'Bus: <object name>'

Default: 'Inherit: auto'

Require names of inputs to match names above — Option to check that input element names match names listed in dialog box

off (default) | on

This parameter might be removed in a future release. To enforce strong data typing, use the Use names from inputs instead of from bus object parameter.

When selected, this parameter checks that the input element names match the names listed in the Block Parameters dialog box. If the element names do not match, Simulink^® returns an error.

Dependencies

• This parameter is ignored if you select Use names from inputs instead of from bus object.

• This parameter reverts to off if you programmatically change Number of inputs.

Rename selected signal — New name for selected input element

'' (default) | character vector

Specify a new name for the selected input element. See Signal Names and Labels for name guidelines.

Dependencies

To enable this parameter, select Require names of inputs to match names above.

Use names from inputs instead of from bus object — Option to use names from input elements instead of from bus object

on (default) | off

By default, the Bus Creator block uses the input element names as the output bus element names, even when you specify a Simulink.Bus object as the data type.

To inherit bus element names from the Bus object, clear this parameter. Clearing the parameter:

• Enforces strong data typing.

• Avoids having to enter an element name multiple times: in the Bus object and in the model. Entering the name multiple times can accidentally create element name mismatches.

• Supports the array of buses requirement to have consistent element names across array elements.

Alternatively, you can enforce strong data typing by checking that input element names match the Bus object element names. Keep this parameter selected and set the Element name mismatch configuration parameter to error.

Dependencies

To enable this parameter, set Output data type to a Bus object.

Programmatic Use

Block Parameter: InheritFromInputs

Type: character vector

Values: 'on' | 'off'

Default: 'on'

Output as nonvirtual bus — Option to output nonvirtual bus

off (default) | on

Select this parameter to output a nonvirtual bus instead of a virtual bus.

All elements in a nonvirtual bus must have the same sample time, even if the elements of the associated Bus object specify inherited sample times for some elements. Any operation resulting in a nonvirtual bus containing elements with different sample rates generates an error. To change the sample time of an element or bus that has a different sample time than the other nonvirtual bus input elements, use a Rate Transition block. For details, see Modify Sample Times for Nonvirtual Buses.

To generate code that uses a C structure to define the structure of the bus that this block creates, enable this parameter.

Dependencies

To enable this parameter, set Output data type to a Bus object.

Programmatic Use

Block Parameter: NonVirtualBus

Type: character vector

Values: 'on' | 'off'

Default: '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

Tips

For buses at subsystem and model interfaces, you can use Out Bus Element blocks instead of a Bus Creator block with an Outport block. Out Bus Element blocks:

• Reduce line complexity and clutter in a block diagram.

• Make it easier to change the interface incrementally.

Extended Capabilities

C/C++ Code Generation

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

Actual data type or capability support depends on block implementation.

HDL Code Generation

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

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

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).

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).

PLC Code Generation
Generate Structured Text code using Simulink® PLC Coder™.

Fixed-Point Conversion

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

Actual data type or capability support depends on block implementation.

Version History

Introduced before R2006a

R2023a: Variable-size input signal upper bound can be smaller than upper bound of variable-size signal that the corresponding Bus Creator block input port can accept

Starting in R2023a, the Bus Creator block supports variable-size input signals with upper bounds smaller than upper bounds of variable-size signals that the corresponding Bus Creator block input ports can accept.

This enhancement allows you to use variable-size input signals when the upper bounds of input signals are not equal to the upper bounds of variable-size signals that the corresponding Bus Creator block input ports can accept.

R2014b: Require names of inputs to match names above parameter is not recommended

The Require names of inputs to match names above parameter might be removed in a future release. To enforce strong data typing, use the Use names from inputs instead of from bus object parameter instead.