Multiport Switch

Select output signal based on control signal

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Libraries:
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 Input	Truncation	Setting for Data Port Order	Block Behavior During Simulation
			Indexing to Select Data Input	Out-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 Case	Diagnostic for Default Case
	None	Warning	Error
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 Case	Diagnostic for Default Case
	None	Warning	Error
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:

Scenario	What to Do	Rationale
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.

Examples

Noncontiguous Values for Data Port Indices of Multiport Switch Block

This example shows how to use a Multiport Switch block that specifies noncontiguous integer values for data ports. The values of the indices are visible on the data port labels. You do not have to open the block dialog box to determine which value maps to each data port.

When you set Data port for default case to Additional data port, an extra port with a * label appears. This port corresponds to the default case, which applies when the control input does not match the data port indices 3, 5, 0, or 18. When that happens in this example, the Multiport Switch block outputs a value of 1.

Zero-Based Indexing for Multiport Switch Data Ports

This example shows a Multiport Switch block that uses zero-based indexing for contiguous ordering of three data ports.

The indices are visible on the data port labels. You do not have to open the block dialog box to determine if the data ports use zero-based or one-based indexing.

When you set Data port for default case to Last data port, the last data port includes a * on the label (in this case, the label is *,2). The comma after the * indicates that the data port index has a value. This port corresponds to the default case, which applies when the control input does not match the data port indices. In this example, the Multiport Switch block outputs a value of -0.1 when the control input does not match the data port indices of 0, 1, or 2.

One-Based Indexing for Multiport Switch Data Ports

The sf_semantics_hotel_checkin model uses a Multiport Switch block. This block uses one-based indexing for contiguous ordering of three data ports.

When you increase the size of the block icon, the indices are visible on the data port labels. You do not have to open the block dialog box to determine whether the data ports use zero-based or one-based indexing.

Enumerated Names for Data Port Indices of the Multiport Switch Block

The sldemo_fuelsys model uses a Multiport Switch block in the fuel_rate_control/fuel_calc/feedforward_fuel_rate subsystem. This block uses the enumerated type sld_FuelModes to specify three data port indices: LOW, RICH, and DISABLED.

When you set Data port for default case to Last data port, the last data port includes a * on the label. The comma and ellipsis after the * indicate that the data port index has a value. This port corresponds to the default case, which applies when the control input does not match the data port indices LOW, RICH, or DISABLED. In this case, the Multiport Switch block outputs a value of 0.

Extended Examples

Model Fault-Tolerant Fuel Control System

Combine Stateflow® and Simulink® capabilities to model hybrid systems. This type of modeling is particularly useful for systems that have numerous possible operational modes based on discrete events. Traditional signal flow is handled in Simulink while changes in control configuration are implemented in Stateflow. The model described in this example represents a fuel control system for a gasoline engine. The system is robust in that it detects individual sensor failures, and the control system is dynamically reconfigured for uninterrupted operation.

• Open Model

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.

• For arrays of buses, Number of data ports must be set to a value of 2 or greater.

Ports

Input

Port_1 — Control signal

scalar

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.

• If the control input is a floating point value that exceeds the datatype range of integers, the Multiport Switch block issues a runtime error. This range includes Inf and NaN.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | image

1 — First data input

scalar | vector | matrix | N-D array

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 | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | string | image

2 — Second data input

scalar | vector | matrix | N-D array

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 | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | string | image

N — Nth data input

scalar | vector | matrix | N-D array

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 | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | string | image

* — Data port for out-of-range inputs

scalar | vector | matrix | N-D array

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 | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | image

Output

Port_1 — Selected data input, based on control signal value

scalar | vector | matrix | N-D array

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. The output data type is the data type of the input port that requires the largest memory space. 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 | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point | enumerated | string | image

Parameters

Main

Data port order — Type of ordering for data input ports

One-based contiguous | Zero-based contiguous | Specify indices

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)

Number of data ports — Number of data input ports

1 | 3 | integer between 1 and 65535

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)

Data port indices — Array of indices for data ports

{1,2,3} (default) | array of indices

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('name of the type').

  For example, enumeration('MyColors') is a valid entry if MyColors is the name of an enumerated type.

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

  For example, enumeration({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:

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

  • enumeration({[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}'

Data port for default case — Port to use for out-of-range inputs

Last data port (default) | Additional data port

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'

Diagnostic for default case — Diagnostic action when control port value does not match data port indices

Error (default) | Warning | None

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'

Sample time (-1 for inherited) — Interval between samples

-1 (default) | scalar | vector

Specify the time interval between samples. To inherit the sample time, set this parameter to -1. For more information, see Specify Sample Time.

Dependencies

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

Programmatic Use

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

Parameter:	SampleTime
Values:	"-1" (default) | scalar or vector in quotes

Signal Attributes

Require all data port inputs to have the same data type — Require all inputs to have the same data type

off (default) | on

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'

Output minimum — Minimum output value for range checking

[] (default) | scalar

Lower value of the output range that the software checks.

The software uses the minimum to perform:

• Parameter range checking (see Specify Minimum and Maximum Values for Block Parameters) for some blocks.

• Simulation range checking (see Specify Signal Ranges and Enable Simulation Range Checking).

• 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).

Tips

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

Programmatic Use

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

Parameter:	OutMin
Values:	'[]' (default) | scalar in quotes

Output maximum — Maximum output value for range checking

[] (default) | scalar

Upper value of the output range that the software checks.

The software uses the maximum value to perform:

• Parameter range checking (see Specify Minimum and Maximum Values for Block Parameters) for some blocks.

• Simulation range checking (see Specify Signal Ranges and Enable Simulation Range Checking).

• 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).

Tips

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

Programmatic Use

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

Parameter:	OutMax
Values:	'[]' (default) | scalar in quotes

Output data type — Specify the output data type

Inherit: Inherit via internal rule (default) | Inherit: Inherit via back propagation | Inherit: Same as first data input | double | single | half | int8 | uint8 | int16 | uint16 | int32 | uint32 | int64 | uint64 | fixdt(1,16) | fixdt(1,16,0) | fixdt(1,16,2^0,0) | string | Simulink.ImageType(480,640,3) | <data type expression>

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 (Fixed-Point Designer).

  • 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.

• Inherit: Same as first data input — Uses the data type of the first data input port.

Programmatic Use

Block Parameter: OutDataTypeStr

Type: character vector

Values: 'Inherit: Inherit via internal rule | 'Inherit: Inherit via back propagation' | 'Inherit: Same as first input' | 'double' | 'single' | 'half' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'fixdt(1,16)' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | 'string' | Simulink.ImageType(480,640,3) | '<data type expression>'

Default: 'Inherit: Inherit via internal rule'

Lock output data type setting against changes by the fixed-point tools — Prevent fixed-point tools from overriding data types

off (default) | on

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'

Integer rounding mode — Specify the rounding mode for fixed-point operations

Floor (default) | Ceiling | Convergent | Nearest | Round | Simplest | Zero

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 Modes (Fixed-Point Designer).

Saturate on integer overflow — Method of overflow action

off (default) | on

Specify whether overflows saturate or wrap.

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

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

For example, the maximum value that the signed 8-bit integer int8 can represent is 127. Any block operation result greater than this maximum value causes overflow of the 8-bit integer.

• With this parameter selected, the block output saturates at 127. Similarly, the block output saturates at a minimum output value of -128.

• With this parameter cleared, the software interprets the overflow-causing value as int8, which can produce an unintended result. For example, a block result of 130 (binary 1000 0010) expressed as int8 is -126.

Tips

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

• Consider clearing this parameter when you want to optimize efficiency of your generated code. Clearing this parameter also helps you to avoid overspecifying how a block handles out-of-range signals. For more information, see Troubleshoot Signal Range Errors.

• When you select this parameter, 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

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

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

Allow different data input sizes (Results in variable-size output signal) — Allow input signals with different sizes

off (default) | on

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'

Mode — Select data type mode

Inherit (default) | Built in | Fixed Point

Select the category of data to specify.

• Inherit — Inheritance rules for data types. Selecting Inherit enables a second menu/text box to the right where you can select the inheritance mode.

• Built in — Built-in data types. Selecting Built in enables a second menu/text box to the right where you can select a built-in data type.

• Fixed point — Fixed-point data types. Selecting Fixed point enables additional parameters that you can use to specify a fixed-point data type.

• Expression — Expressions that evaluate to data types. Selecting Expression enables a second menu/text box to the right, where you can enter the expression.

For more information, see Specify Data Types Using Data Type Assistant.

Dependencies

To enable this parameter, click the Show data type assistant button.

Data type override — Specify data type override mode for this signal

Inherit | Off

Select the data type override mode for this signal.

• When you select Inherit, Simulink inherits the data type override setting from its context, that is, from the block, Simulink.Signal object or Stateflow^® chart in Simulink that is using the signal.

• When you select Off, Simulink ignores the data type override setting of its context and uses the fixed-point data type specified for the signal.

For more information, see Specify Data Types Using Data Type Assistant in the Simulink documentation.

Dependencies

To enable this parameter, set Mode to Built in or Fixed point.

Tips

The ability to turn off data type override for an individual data type provides greater control over the data types in your model when you apply data type override. For example, you can use this option to ensure that data types meet the requirements of downstream blocks regardless of the data type override setting.

Signedness — Specify signed or unsigned

Signed (default) | Unsigned

Specify whether the fixed-point data is signed or unsigned. Signed data can represent positive and negative values, but unsigned data represents positive values only.

• Signed, specifies the fixed-point data as signed.

• Unsigned, specifies the fixed-point data as unsigned.

For more information, see Specify Data Types Using Data Type Assistant.

Dependencies

To enable this parameter, set the Mode to Fixed point.

Scaling — Method for scaling fixed-point data

Best precision (default) | Binary point | Slope and bias

Specify the method for scaling your fixed-point data to avoid overflow conditions and minimize quantization errors. For more information, see Specifying a Fixed-Point Data Type.

Dependencies

To enable this parameter, set Mode to Fixed point.

Word length — Bit size of the word that holds the quantized integer

16 (default) | integer from 0 to 32

Specify the bit size of the word that holds the quantized integer. For more information, see Specifying a Fixed-Point Data Type.

Dependencies

To enable this parameter, set Mode to Fixed point.

Fraction length — Specify fraction length for fixed-point data type

0 (default) | scalar integer

Specify fraction length for fixed-point data type as a positive or negative integer. For more information, see Specifying a Fixed-Point Data Type.

Dependencies

To enable this parameter, set Scaling to Binary point.

Slope — Specify slope for the fixed-point data type

2^0 (default) | positive, real-valued scalar

Specify slope for the fixed-point data type. For more information, see Specifying a Fixed-Point Data Type.

Dependencies

To enable this parameter, set Scaling to Slope and bias.

Bias — Specify bias for the fixed-point data type

0 (default) | real-valued scalar

Specify bias for the fixed-point data type as any real number. For more information, see Specifying a Fixed-Point Data Type.

Dependencies

To enable this parameter, set Scaling to Slope and bias.

Block Characteristics

Data Types	Boolean | bus | double | enumerated | fixed point | half | 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™.

HDL Code Generation

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

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

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

General
CodingStyle	Specify whether to generate HDL code with case statements or if-else statements. By default, HDL Coder generates if-else statements. See also CodingStyle (HDL Coder).
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).

Native Floating Point
LatencyStrategy	Specify whether to map the blocks in your design to inherit, Max, Min, or Zero for the floating-point operator. The default is inherit. See also LatencyStrategy (HDL Coder).

Complex Data Support

This block supports code generation for complex signals.

Setting Data Port Indices Using Specify Indices mode

You can specify the data port indices to the input port using specify indices mode. To configure the Multiport Switch block with specify indices mode, set the Data port order block parameter to Specify indices. Then, enter the port indices in the Data port indices block parameter. For a model targeted for HDL code generation, you can use these input data types for the control input in a specify indices mode:

• Fixed-point and floating-point types

• Signed and unsigned integer types

• Enumerated types

• Vector, matrix, and bus types

Using an Enumerated Type as Port Index

You can set Data port order to Specify indices, and enter enumeration values for the Data port indices. For example, you can connect the Enumerated Constant block to the Multiport Switch control port and use the enumerated types as data port indices.

Restrictions

You must avoid using of NaN or out of range values at the control port. It can cause simulation mismatch in the validation model.

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

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

Version History

Introduced before R2006a

R2024a: Multiport Switch block has runtime error when input has floating point value

The Multiport Switch block now issues a runtime error when the control signal in the first port has a floating point value that exceeds the datatype range of integers. This range includes Inf and NaN.