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Multiport Switch

Choose between multiple block inputs

  • Library:
  • Simulink / Signal Routing

    HDL Coder / Signal Routing

Description

The Multiport Switch block determines which of several inputs to the block passes to the output. The block bases this decision on the value of the first input. The first input is the control input and the remaining inputs are the data inputs. The value of the control input determines which data input passes to the output.

The table summarizes how the block interprets the control input and determines the data input that is passed to the output.

Control InputTruncationSetting for Data Port OrderBlock Behavior During Simulation
Indexing to Select Data InputOut-of-Range Condition

Integer value

None

Zero-based contiguous

Zero-based indexing

The control input is less than 0 or greater than the number of data inputs minus one.

One-based contiguous

One-based indexing

The control input is less than 1 or greater than the number of data inputs.

Specify indices

Indices you specify

The control input does not correspond to any specified data port index.

Not an integer value

The block truncates the value to an integer by rounding to zero.

Zero-based contiguous

Zero-based indexing

The truncated control input is less than 0 or greater than the number of data inputs minus one.

One-based contiguous

One-based indexing

The truncated control input is less than 1 or greater than the number of data inputs.

Specify indices

Indices you specify

The truncated control input does not correspond to any specified data port index.

For information on how the block handles the out-of-range condition, see How the Block Handles an Out-of-Range Control Input.

Multiport Switch Configured as an Index Vector Block

An Index Vector is a special configuration of a Multiport Switch block in which you specify one data input and the control input is zero-based. The block output is the element of the input vector whose index matches the control input. For example, if the input vector is [18 15 17 10] and the control input is 3, the element that matches the index of 3 (zero-based) is 10, and that becomes the output value.

To configure a Multiport Switch block to work as an Index Vector block, set Number of data ports to 1 and Data port order to Zero-based contiguous.

How the Block Handles an Out-of-Range Control Input

For an input with an integer value less than intmax(‘int32’), the input is out of range when the value does not match any data port indices. For a control input that is not an integer value, the input is out of range when the truncated value does not match any data port indices. In both cases, the block behavior depends on your settings for Data port for default case and Diagnostic for default case.

Note

If the control input is larger than intmax(‘int32’), the block wraps the input value to an integer.

Behavior for Simulation

The following behavior applies only to simulation for your model.

Data Port for Default CaseDiagnostic for Default Case
NoneWarningError

Last data port

Use the last data port and do not report any warning or error.

Use the last data port and report a warning.

Report an error and stop simulation.

Additional data port

Use the additional data port with a * label and do not report any warning or error.

Use the additional data port with a * label and report a warning.

Report an error and stop simulation.

Behavior for Code Generation

The following behavior applies to code generation for your model.

Data Port for Default CaseDiagnostic for Default Case
NoneWarningError

Last data port

Use the last data port.

Use the last data port.

Use the last data port.

Additional data port

Use the additional data port with a * label.

Use the additional data port with a * label.

Use the additional data port with a * label.

Use Data Inputs That Have Different Dimensions

If two signals have a different number of dimensions or different dimension lengths, you can use the signals as data inputs to a Multiport Switch block. In the block dialog box, select the parameter Allow different data input sizes. In this case, the output of the block is a variable-size signal. If you do not select this parameter, the block generates an error.

For more information about the parameter, see Allow different data input sizes (Results in variable-size output signal). For more information about variable-size signals, see Variable-Size Signal Basics.

Rules That Determine the Block Behavior

You specify the number of data inputs with Number of data ports.

  • If you set Number of data ports to 1, the block behaves as an index selector or index vector and not as a multiport switch. For more details, see Multiport Switch Configured as an Index Vector Block.

  • If you set Number of data ports to an integer greater than 1, the block behaves as a multiport switch. The block output is the data input that corresponds to the value of the control input. If at least one of the data inputs is a vector, the block output is a vector. In this case, the block expands any scalar inputs to vectors.

  • If all the data inputs are scalar, the output is a scalar.

Guidelines on Setting Parameters for Enumerated Control Port

When the control port on the Multiport Switch block is of enumerated type, follow these guidelines:

ScenarioWhat to DoRationale

The enumerated type contains a value that represents invalid, out-of-range, or uninitialized values.

  • Set Data port order to Specify indices.

  • Set Data port indices to use this value for the last data port.

  • Set Data port for default case to Last data port.

This block configuration handles invalid values that the enumerated type explicitly represents.

The enumerated type contains only valid enumerated values. However, a data input port can get invalid values of enumerated type.

  • Set Data port for default case to Additional data port.

This block configuration handles invalid values that the enumerated type does not explicitly represent.

The enumerated type contains only valid enumerated values. Data input ports can never get invalid values of enumerated type.

  • Set Data port for default case to Last data port.

  • Set Diagnostic for default case to None.

This block configuration avoids unnecessary diagnostic action.

The block does not have a data input port for every value of the enumerated type.

  • Set Data port for default case to Additional data port.

This block configuration handles enumerated values that do not have a data input port, along with invalid values.

Limitations

  • If the data inputs to the Multiport Switch block are buses, the element names of both buses must be the same. Using the same element names ensures that the output bus has the same element names no matter which input bus the block selects. To ensure that your model meets this requirement, use a bus object to define the buses and set the Element name mismatch diagnostic to error. See Connectivity Diagnostics Overview for more information.

Ports

Input

expand all

The control signal can be of any data type that Simulink® supports, including fixed-point and enumerated types. When the control input is not an integer value, the block truncates the value to an integer by rounding to zero.

For information on control signals of enumerated type, see Guidelines on Setting Parameters for Enumerated Control Port.

For information on how the block handles the out-of-range condition, see How the Block Handles an Out-of-Range Control Input.

Limitations

  • If the control signal is numeric, the control signal cannot be complex.

  • If the control signal is an enumerated signal, the block uses the value of the underlying integer to select a data port.

  • If the underlying integer does not correspond to a data port, an error occurs.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

First data input, specified as a scalar, vector, matrix, or N-D array. All input data signals can be of any data type that Simulink supports.

  • If all the data inputs are scalar, the output is scalar

  • If at least one of the data inputs is a vector, the block output is a vector. In this case, the block expands any scalar inputs to vectors.

  • If any two nonscalar signals have a different number of dimensions or different dimension lengths, select the Allow different data input sizes check box. For more information, see Use Data Inputs That Have Different Dimensions

  • If any data signal is of an enumerated type, all others must be of the same enumerated type.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Second data input, specified as a scalar, vector, matrix, or N-D array. All input data signals can be of any data type that Simulink supports.

  • If all the data inputs are scalar, the output is scalar

  • If at least one of the data inputs is a vector, the block output is a vector. In this case, the block expands any scalar inputs to vectors.

  • If any two nonscalar signals have a different number of dimensions or different dimension lengths, select the Allow different data input sizes check box. For more information, see Use Data Inputs That Have Different Dimensions

  • If any data signal is of an enumerated type, all others must be of the same enumerated type.

Dependencies

To enable this port, set Number of data ports to an integer greater than 1.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Nth data input, specified as a scalar, vector, matrix, or N-D array. All input data signals can be of any data type that Simulink supports.

  • If all the data inputs are scalar, the output is scalar

  • If at least one of the data inputs is a vector, the block output is a vector. In this case, the block expands any scalar inputs to vectors.

  • If any two nonscalar signals have a different number of dimensions or different dimension lengths, select the Allow different data input sizes check box. For more information, see Use Data Inputs That Have Different Dimensions

  • If any data signal is of an enumerated type, all others must be of the same enumerated type.

Dependencies

To enable the Nth input port, set Number of data ports to an integer value greater than or equal to N.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Input data port for out-of-range control signal inputs, specified as a scalar, vector, matrix, or N-D array. All input data signals can be of any data type that Simulink supports. If any data signal is of an enumerated type, all others must be of the same enumerated type. If any two signals have a different number of dimensions or different dimension lengths, select the Allow different data input sizes check box. For more information, see Use Data Inputs That Have Different Dimensions.

Dependencies

To create an additional data port for out-of-range control signal inputs, set Data port for default case to Additional data port. When you set Data port for default case to Last data port, the block uses the last data port for output when the control signal value does not match any data port indices.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Output

expand all

The block outputs one of the data inputs, selected according to the control signal value. The output has the same dimensions as the corresponding data input. When you select the Allow different data input sizes check box, the output of the block is a variable size signal.

Data Types: single | double | int8 | int16 | int32 | uint8 | uint16 | uint32 | Boolean | fixed point | enumerated | bus

Parameters

expand all

Main

Specify the type of ordering for your data input ports.

  • Zero-based contiguous — Block uses zero-based indexing for ordering contiguous data ports. This is the default value of the Index Vector block.

  • One-based contiguous — Block uses one-based indexing for ordering contiguous data ports. This is the default value of the Multiport Switch block

  • Specify indices — Block uses noncontiguous indexing for ordering data ports.

Tips

  • When the control port is of enumerated type, select Specify indices.

  • If you select Zero-based contiguous or One-based contiguous, verify that the control port is not of enumerated type. This configuration is deprecated and produces an error. You can run the Upgrade Advisor on your model to replace each Multiport Switch block of this configuration with a block that explicitly specifies data port indices. See Model Upgrades.

  • Avoid situations where the block contains unused data ports for simulation or code generation. When the control port is of fixed-point or built-in data type, verify that all data port indices are representable with that type. Otherwise, the following block behavior occurs.

    If the Block Has Unused Data Ports and Data Port Order Is:The Block Produces:
    Zero-based contiguous or One-based contiguous A warning
    Specify indices An error

Dependencies

Selecting Zero-based contiguous or One-based contiguous enables the Number of data ports parameter.

Selecting Specify indices enables the Data port indices parameter.

Programmatic Use

Block Parameter: DataPortOrder
Type: character vector
Values: 'Zero-based contiguous' | 'One-based contiguous' | 'Specify indices'
Default: 'One-based contiguous' (Multiport Switch) 'Zero-based contiguous' (Index Vector)

Specify the number of data input ports to the block. The total number of input ports is the number you specify, plus one for the control signal input port, and plus one more if you set Data port for default case to Additional data port.

Dependencies

To enable this parameter, set Data port order to Zero-based contiguous or One-based contiguous.

Programmatic Use

Block Parameter: Inputs
Type: character vector
Values: integer between 1 and 65536
Default: '3' (Multiport Switch) '1' (Index Vector)

Specify an array of indices for your data ports. The block icon changes to match the data port indices you specify.

Tips

  • To specify an array of indices that correspond to all values of an enumerated type, enter enumeration('type_name') for this parameter. Do not include braces.

    For example, enumeration('MyColors') is a valid entry.

  • To enter specific values of an enumerated type, use the type_name.enumerated_name format. Do not enter the underlying integer value.

    For example, {MyColors.Red, MyColors.Green, MyColors.Blue} is a valid entry.

  • To indicate that more than one value maps to a data port, use brackets.

    For example, the following entries are both valid:

    • {MyColors.Red, MyColors.Green, [MyColors.Blue, MyColors.Yellow]}

    • {[3,5],0,18}

  • If the control port is of fixed-point or built-in data type, the values for Data port indices must be representable with that type. Otherwise, an error appears at compile time to alert you to unused data ports.

  • If the control port is of enumerated data type, the values for Data port indices must be enumerated values of that type.

  • If Data port indices contains values of enumerated type, the control port must be of that data type.

Dependencies

To enable this parameter, set Data port order to Specify indices.

Programmatic Use

Block Parameter: DataPortIndices
Type: character vector
Values: array of indices
Default: '{1,2,3}'

Specify whether to use the last data port for out-of-range inputs, or to use an additional port. An asterisk (*) next to the port name indicates the port the block uses when the control port value does not match any data port indices.

  • Last data port — Block uses the last data port for output when the control port value does not match any data port indices.

  • Additional data port — Block uses an additional data port for output when the control port value does not match any data port indices.

Tip

If you set this parameter to Additional data port and Number of data ports is 3, the number of input ports on the block is 5. The first input is the control port, the next three inputs are data ports, and the fifth input is the default port for out-of-range inputs.

Programmatic Use

Block Parameter: DataPortForDefault
Type: character vector
Values: 'Last data port' | 'Additional data port'
Default: 'Last data port'

Specify the diagnostic action to take when the control port value does not match any data port indices.

  • None — Produce no response.

  • Warning — Display a warning and continue the simulation.

  • Error — Terminate the simulation and display an error. In this case, the Data port for default case is used only for code generation and not simulation.

For more information, see How the Block Handles an Out-of-Range Control Input.

Programmatic Use

Block Parameter: DiagnosticForDefault
Type: character vector
Values: 'None' | 'Warning' | 'Error'
Default: 'Error'

Specify the sample time as a value other than -1. For more information, see Specify Sample Time.

Dependencies

This parameter is not visible unless it is explicitly set to a value other than -1. To learn more, see Blocks for Which Sample Time Is Not Recommended.

Programmatic Use

Block Parameter: SampleTime
Type: character vector
Values: scalar
Default: '-1'

Signal Attributes

Select this check box to require that all data input ports have the same data type. When you clear this check box, the block allows data port inputs to have different data types.

Programmatic Use

Block Parameter: InputSameDT
Type: character vector
Values: 'off' | 'on'
Default: 'off'

Lower value of the output range that Simulink checks.

Simulink uses the minimum to perform:

Note

Output minimum does not saturate or clip the actual output signal. Use the Saturation block instead.

Programmatic Use

Block Parameter: OutMin
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Upper value of the output range that Simulink checks.

Simulink uses the maximum value to perform:

Note

Output maximum does not saturate or clip the actual output signal. Use the Saturation block instead.

Programmatic Use

Block Parameter: OutMax
Type: character vector
Values: '[ ]'| scalar
Default: '[ ]'

Choose the data type for the output. The type can be inherited, specified directly, or expressed as a data type object such as Simulink.NumericType.

When you select an inherited option, the block behaves as follows:

  • Inherit: Inherit via internal rule—Simulink chooses a data type to balance numerical accuracy, performance, and generated code size, while taking into account the properties of the embedded target hardware. If you change the embedded target settings, the data type selected by the internal rule might change. It is not always possible for the software to optimize code efficiency and numerical accuracy at the same time. If the internal rule doesn’t meet your specific needs for numerical accuracy or performance, use one of the following options:

    • Specify the output data type explicitly.

    • Explicitly specify a default data type such as fixdt(1,32,16) and then use the Fixed-Point Tool to propose data types for your model. For more information, see fxptdlg.

    • To specify your own inheritance rule, use Inherit: Inherit via back propagation and then use a Data Type Propagation block. Examples of how to use this block are available in the Signal Attributes library Data Type Propagation Examples block.

  • Inherit: Inherit via back propagation — Uses the data type of the driving block.

Programmatic Use

Block Parameter: OutDataTypeStr
Type: character vector
Values: 'Inherit: Inherit via internal rule | 'Inherit: Inherit via back propagation' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | '<data type expression>'
Default: 'Inherit: Inherit via internal rule'

Select to lock the output data type setting of this block against changes by the Fixed-Point Tool and the Fixed-Point Advisor. For more information, see Use Lock Output Data Type Setting (Fixed-Point Designer).

Programmatic Use

Block Parameter: LockScale
Type: character vector
Values: 'off' | 'on'
Default: 'off'

Choose one of these rounding modes.

Ceiling

Rounds both positive and negative numbers toward positive infinity. Equivalent to the MATLAB® ceil function.

Convergent

Rounds number to the nearest representable value. If a tie occurs, rounds to the nearest even integer. Equivalent to the Fixed-Point Designer™ convergent function.

Floor

Rounds both positive and negative numbers toward negative infinity. Equivalent to the MATLAB floor function.

Nearest

Rounds number to the nearest representable value. If a tie occurs, rounds toward positive infinity. Equivalent to the Fixed-Point Designer nearest function.

Round

Rounds number to the nearest representable value. If a tie occurs, rounds positive numbers toward positive infinity and rounds negative numbers toward negative infinity. Equivalent to the Fixed-Point Designer round function.

Simplest

Automatically chooses between round toward floor and round toward zero to generate rounding code that is as efficient as possible.

Zero

Rounds number toward zero. Equivalent to the MATLAB fix function.

Programmatic Use

Block Parameter: RndMeth
Type: character vector
Values: 'Ceiling' | 'Convergent' | 'Floor' | 'Nearest' | 'Round' | 'Simplest' | 'Zero'
Default: 'Floor'

See Also

For more information, see Rounding (Fixed-Point Designer).

Specify whether overflows saturate or wrap.

  • off — Overflows wrap to the appropriate value that the data type can represent.

    For example, the number 130 does not fit in a signed 8-bit integer and wraps to -126.

  • on — Overflows saturate to either the minimum or maximum value that the data type can represent.

    For example, an overflow associated with a signed 8-bit integer can saturate to -128 or 127.

Tip

  • Consider selecting this check box when your model has a possible overflow and you want explicit saturation protection in the generated code.

  • Consider clearing this check box when you want to optimize efficiency of your generated code.

    Clearing this check box also helps you to avoid overspecifying how a block handles out-of-range signals. For more information, see Check for Signal Range Errors.

  • When you select this check box, saturation applies to every internal operation on the block, not just the output or result.

  • In general, the code generation process can detect when overflow is not possible. In this case, the code generator does not produce saturation code.

Programmatic Use

Block Parameter: SaturateOnIntegerOverflow
Type: character vector
Values: 'off' | 'on'
Default: 'off'

Select this check box to allow input signals with different sizes.

  • On — Allows input signals with different sizes, and propagate the input signal size to the output signal. In this mode, the block produces a variable-size output signal.

  • Off — Requires that all nonscalar data input signals be the same size.

Programmatic Use

Parameter: AllowDiffInputSizes
Type: character vector
Value: 'on' | 'off'
Default: 'off'

Block Characteristics

Data Types

Boolean | bus | double | enumerated | fixed point | integer | single | string

Direct Feedthrough

yes

Multidimensional Signals

yes

Variable-Size Signals

yes

Zero-Crossing Detection

no

Extended Capabilities

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

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

Fixed-Point Conversion
Convert floating-point algorithms to fixed point using Fixed-Point Designer™.

Introduced before R2006a