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Discrete-Time Integrator

Perform discrete-time integration or accumulation of signal

Library

Discrete

Description

Capabilities of the Discrete-Time Integrator Block

You can use the Discrete-Time Integrator block in place of the Integrator block to create a purely discrete system. With the Discrete-Time Integrator block, you can:

  • Define initial conditions on the block dialog box or as input to the block.

  • Define an input gain (K) value.

  • Output the block state.

  • Define upper and lower limits on the integral.

  • Reset the state depending on an additional reset input.

Output Equations

The block starts from the first time step, n = 0, with either initial output y(0) = IC or initial state x(0) = IC, depending on the Initial condition setting parameter value.

For a given step n > 0 with simulation time t(n), Simulink® updates output y(n) as follows:

  • Forward Euler method:

    y(n) = y(n-1) + K*[t(n)-t(n-1)]*u(n-1)
  • Backward Euler method:

    y(n) = y(n-1) + K*[t(n)-t(n-1)]*u(n)
  • Trapezoidal method:

    y(n) = y(n-1) + K*[t(n)-t(n-1)]*[u(n)+u(n-1)]/2

Simulink automatically selects a state-space realization of these output equations depending on the block sample time, which can be explicit or triggered. When using explicit sample time, t(n)-t(n-1) reduces to the sample time T for all n > 0. For more information on these methods, see Integration and Accumulation Methods.

Integration and Accumulation Methods

The block can integrate or accumulate using the forward Euler, backward Euler, and trapezoidal methods. Assume that u is the input, y is the output, and x is the state. For a given step n, Simulink updates y(n) and x(n+1). In integration mode, T is the block sample time (delta T in the case of triggered sample time). In accumulation mode, T = 1. The block sample time determines when the output is computed but not the output value. K is the gain value. Values clip according to upper or lower limits.

  • Forward Euler method (default), also known as forward rectangular, or left-hand approximation

    For this method, the software approximates 1/s as T/(z-1). The expressions for the output of the block at step n are:

    x(n+1) = x(n) + K*T*u(n)
    y(n) = x(n)

    The block uses the following steps to compute the output:

    Step 0: 		y(0)   = IC (clip if necessary)
    			x(1)   = y(0) + K*T*u(0)
    
    Step 1:			y(1)   = x(1)
    			x(2)   = x(1) + K*T*u(1)
    
    Step n:			y(n)   = x(n)
    			x(n+1) = x(n) + K*T*u(n) (clip if necessary)

    Using this method, input port 1 does not have direct feedthrough.

  • Backward Euler method, also known as backward rectangular or right-hand approximation

    For this method, the software approximates 1/s as T*z/(z-1). The resulting expression for the output of the block at step n is

    y(n) = y(n-1) + K*T*u(n).

    Let x(n) = y((n)-1). The block uses these steps to compute the output.

    If the parameter Initial condition setting is set to Output:

    Step 0:			y(0)  = IC (clipped if necessary)
    			x(1)   = y(0)

    If the parameter Initial condition setting is set to State (most efficient):

    Step 0:			x(0)   = IC (clipped if necessary)
    			x(1)   = y(0) = x(0) + K*T*u(0)
    
    Step 1:			y(1)   = x(1) + K*T*u(1)
    			x(2)   = y(1)
    
    Step n:			y(n)   = x(n) + K*T*u(n)
    			x(n+1) = y(n)

    Using this method, input port 1 has direct feedthrough.

  • Trapezoidal method

    For this method, the software approximates 1/s as

    T/2*(z+1)/(z-1).

    When T is fixed (equal to the sampling period), the expressions to compute the output are:

    x(n) = y(n-1) + K*T/2 * u(n-1)
    y(n) = x(n) + K*T/2*u(n)

    If the Initial condition setting parameter is set to Output:

    Step 0:			y(0) = IC (clipped if necessary)
    			x(1)   = y(0) + K*T/2*u(0)

    If the Initial condition setting parameter is set to State (most efficient):

    Step 0:			x(0)   = IC (clipped if necessary)
    			y(0)   = x(0) + K*T/2*u(0)
    			x(1)   = y(0) + K*T/2*u(0)
    
    Step 1:			y(1)   = x(1) + K*T/2*u(1)
    			x(2)   = y(1) + K*T/2*u(1)
    
    Step n:			y(n)   = x(n) + K*T/2*u(n)
    			x(n+1) = y(n) + K*T/2*u(n)

    Here, x(n+1) is the best estimate of the next output. It is not the same as the state, in that x(n) is not equal to y(n).

    If T is variable (for example, obtained from the triggering times), the block uses these steps to compute the output.

    If the Initial condition setting parameter is set to Output:

    Step 0:			y(0) = IC (clipped if necessary)
    			x(1)   = y(0)

    If the Initial condition setting parameter is set to State (most efficient):

    Step 0:			x(0)   = IC (clipped if necessary)
    			x(1)   = y(0) = x(0) + K*T/2*u(0)
    
    Step 1:			y(1)   = x(1) + T/2*(u(1) + u(0))
    			x(2)   = y(1)
    
    Step n:			y(n)   = x(n) + T/2*(u(n) + u(n-1))
    			x(n+1) = y(n)

    Using this method, input port 1 has direct feedthrough.

Define Initial Conditions

You can define the initial conditions as a parameter on the block dialog box or input them from an external signal:

  • To define the initial conditions as a block parameter, set the Initial condition source parameter to internal and enter the value in the Initial condition text box.

  • To provide the initial conditions from an external source, set the Initial condition source parameter to external. An additional input port appears on the block.

When to Use the State Port

Use the state port instead of the output port:

  • When the output of the block is fed back into the block through the reset port or the initial condition port, causing an algebraic loop. For an example, see the sldemo_bounce_two_integrators model.

  • When you want to pass the state from one conditionally executed subsystem to another, which can cause timing problems. For an example, see the sldemo_clutch model.

You can work around these problems by passing the state through the state port rather than the output port. Simulink generates the state at a slightly different time from the output, which protects your model from these problems. To output the block state, select the Show state port check box. The state port appears on the top of the block

Limit the Integral

To keep the output within certain levels, select the Limit output check box and enter the limits in the corresponding text box. Doing so causes the block to function as a limited integrator. When the output reaches the limits, the integral action turns off to prevent integral windup. During a simulation, you can change the limits but you cannot change whether the output is limited. The table shows how the block determines output.

IntegralOutput
Less than or equal to the Lower saturation limit and the input is negativeHeld at the Lower saturation limit
Between the Lower saturation limit and the Upper saturation limitThe integral
Greater than or equal to the Upper saturation limit and the input is positiveHeld at the Upper saturation limit

To generate a signal that indicates when the state is being limited, select the Show saturation port check box. A new saturation port appears below the block output port:

The signal has one of three values:

  • 1 indicates that the upper limit is being applied.

  • 0 indicates that the integral is not limited.

  • -1 indicates that the lower limit is being applied.

Reset the State

The block can reset its state to the initial condition you specify, based on an external signal. To cause the block to reset its state, select one of the External reset parameter options. A trigger port appears that indicates the trigger type:

The reset port has direct feedthrough. If the block output feeds back into this port, either directly or through a series of blocks with direct feedthrough, an algebraic loop results. To resolve this loop, feed the output of the block state port into the reset port instead. To access the block state, select the Show state port check box.

Reset Trigger Types

The External reset parameter lets you determine the attribute of the reset signal that triggers the reset. The trigger options include:

  • rising – Resets the state when the reset signal has a rising edge. For example, this figure shows the effect that a rising reset trigger has on backward Euler integration.

  • falling – Resets the state when the reset signal has a falling edge. For example, this figure shows the effect that a falling reset trigger has on backward Euler integration.

  • either – Resets the state when the reset signal rises or falls. For example, the following figure shows the effect that an either reset trigger has on backward Euler integration.

  • level – Resets and holds the output to the initial condition while the reset signal is nonzero. For example, this figure shows the effect that a level reset trigger has on backward Euler integration.

  • sampled level – Resets the output to the initial condition when the reset signal is nonzero. For example, this figure shows the effect that a sampled level reset trigger has on backward Euler integration.

      Note:   The sampled level reset option requires fewer computations, making it more efficient than the level reset option. However, the sampled level reset option can introduce a discontinuity when integration resumes.

Behavior When Using Simplified Initialization Mode

Simplified initialization mode is enabled when you set Configuration Parameters > Diagnostics > Data Validity > Underspecified initialization detection is set to Simplified. If you use simplified initialization mode, the behavior of the Discrete-Time Integrator block differs from classic initialization mode. The new initialization behavior is more robust and provides more consistent behavior in these cases:

  • In algebraic loops

  • On enable and disable

  • When comparing results using triggered sample time against explicit sample time, where the block is triggered at the same rate as the explicit sample time

Simplified initialization mode enables easier conversion from Continuous-Time Integrator blocks to Discrete-Time Integrator blocks, because the initial conditions have the same meaning for both blocks.

For more information on classic and simplified initialization modes, see Underspecified initialization detection.

Enable and Disable Behavior in Simplified Initialization Mode

When you use simplified initialization mode, the enable and disable behavior of the block is simplified as follows:

At disable time td:

 y(td) = y(td-1)

At enable time te:

  • If parent subsystem resets on enable and Initial condition setting is set to Output:

    y(te) = IC
  • If parent subsystem resets on enable and Initial condition setting is set to State (most efficient):

    x(te) = IC
  • In all other cases (see following figure):

    y(te) = y(td)

Iterator Subsystems

When using simplified initialization mode, you cannot place the Discrete-Time Integrator block in an Iterator Subsystem.

In simplified initialization mode, Iterator subsystems do not maintain elapsed time. Thus, if a Discrete-Time Integrator block, which needs elapsed time, is placed inside an Iterator Subsystem block, Simulink reports an error.

Triggered Subsystems and Function-Call Subsystems

Simulink does not support model simulation when all the following conditions are true:

  • A Discrete-Time Integrator block is placed within a triggered subsystem or a function-call subsystem.

  • The block's Initial condition setting parameter is set to State (most efficient).

  • Simplified initialization mode is enabled.

Behavior When Used in an Enabled Subsystem Inside a Function-Call Subsystem

Suppose that you have a function-call subsystem that contains an enabled subsystem, which contains a Discrete-Time Integrator block. The following behavior applies.

Integrator MethodSample Time Type of Function-Call Trigger PortValue of delta T When Function-Call Subsystem Executes for the First Time After EnabledReason for Behavior

Forward Euler

Triggered

t — tstart

When the function-call subsystem executes for the first time, the integrator algorithm uses tstart as the previous simulation time.

Backward Euler and Trapezoidal

Triggered

t — tprevious

When the function-call subsystem executes for the first time, the integrator algorithm uses tprevious as the previous simulation time.

Forward Euler, Backward Euler, and Trapezoidal

Periodic

Sample time of the function-call generator

In periodic mode, the Discrete-Time Integrator block uses sample time of the function-call generator for delta T.

Data Type Support

The Discrete-Time Integrator block accepts real signals of the following data types:

  • Floating point

  • Built-in integer

  • Fixed point

For more information, see Data Types Supported by Simulink in the Simulink documentation.

Parameters and Dialog Box

During simulation, the block uses the following values:

  • The initial value of the signal object to which the state name is resolved

  • Min and Max values of the signal object

For more information, see States in the Simulink Coder™ documentation.

Show data type assistant

Display the Data Type Assistant.

Settings

The Data Type Assistant helps you set the Output data type parameter.

For more information, see Specify Block Output Data Types.

Integrator method

Specify the integration or accumulation method.

Settings

Default: Integration: Forward Euler

Integration: Forward Euler

Integrator method is Forward Euler.

Integration: Backward Euler

Integrator method is Backward Euler.

Integration: Trapezoidal

Integrator method is Trapezoidal.

Accumulation: Forward Euler

Accumulation method is Forward Euler.

Accumulation: Backward Euler

Accumulation method is Backward Euler.

Accumulation: Trapezoidal

Accumulation method is Trapezoidal.

Command-Line Information

Parameter: IntegratorMethod
Type: string
Value: 'Integration: Forward Euler' | 'Integration: Backward Euler' | 'Integration: Trapezoidal' | 'Accumulation: Forward Euler' | 'Accumulation: Backward Euler' | 'Accumulation: Trapezoidal'
Default: 'Integration: Forward Euler'

Gain value

Specify a scalar, vector, or matrix by which to multiply the integrator input. Each element of the gain must be a positive real number.

Settings

Default: 1.0

  • Specifying a value other than 1.0 (the default) is semantically equivalent to connecting a Gain block to the input of the integrator.

  • Valid entries include:

    • double(1.0)

    • single(1.0)

    • [1.1 2.2 3.3 4.4]

    • [1.1 2.2; 3.3 4.4]

  • Using this parameter to specify the input gain eliminates a multiplication operation in the generated code. However, this parameter must be nontunable to realize this benefit. If the Model Configuration Parameters dialog box declares this parameter as tunable, Simulink Coder generates a warning during code generation. If you want to tune the input gain, set this parameter to 1.0 and use an external Gain block to specify the input gain.

Command-Line Information

Parameter: gainval
Type: string
Value: '1.0'
Default: '1.0'

External reset

Reset the states to their initial conditions when a trigger event occurs in the reset signal.

Settings

Default: none

none

Do not reset the state to initial conditions.

rising

Reset the state when the reset signal has a rising edge.

falling

Reset the state when the reset signal has a falling edge.

either

Reset the state when the reset signal rises or falls.

level

Reset and holds the output to the initial condition while the reset signal is nonzero.

sampled level

Reset the output to the initial condition when the reset signal is nonzero.

Command-Line Information

Parameter: ExternalReset
Type: string
Value: 'none' | 'rising' | 'falling' | 'either' | 'level' | 'sampled level'
Default: 'none'

Initial condition source

Get the initial conditions of the states.

Settings

Default: internal

internal

Get the initial conditions of the states from the Initial condition parameter.

external

Get the initial conditions of the states from an external block.

Tips

Simulink software does not allow the initial condition of this block to be inf or NaN.

Dependencies

Selecting internal enables the Initial condition parameter.

Selecting external disables the Initial condition parameter.

Command-Line Information

Parameter: InitialConditionSource
Type: string
Value: 'internal' | 'external'
Default: 'internal'

Initial condition

Specify the states' initial conditions.

Settings

Default: 0

Minimum: value of Output minimum parameter

Maximum: value of Output maximum parameter

Tips

Simulink software does not allow the initial condition of this block to be inf or NaN.

Dependencies

Setting Initial condition source to internal enables this parameter.

Setting Initial condition source to external disables this parameter.

Command-Line Information

Parameter: InitialCondition
Type: scalar or vector
Value: '0'
Default: '0'

Initial condition setting

Specify whether to apply the Initial condition parameter to the block state or output. This initial condition is also used as the reset value. This parameter was named Use initial condition as initial and reset value for in Simulink before R2014a.

Settings

Default: Output

State (most efficient)

Set the following initial conditions:

x(0) = IC

At reset:

x(n) = IC

Output

Set the following initial conditions:

y(0) = IC

At reset:

y(n) = IC

Compatibility

Use this option to maintain compatibility with Simulink models created before R2014a. You cannot select this option for Discrete-Time Integrator blocks in Simulink models but you can select it for Discrete-Time Integrator blocks in a library.

Prior to R2014a, the option State (most efficient) was known as State only (most efficient). The option Output was known as State and output. The behavior of the block with the option Compatibility is as follows.

  • If Configuration Parameters > Diagnostics > Data Validity > Underspecified initialization detection is set to Classic, the Initial condition setting parameter behaves as State (most efficient).

  • If Configuration Parameters > Diagnostics > Data Validity > Underspecified initialization detection is set to Simplified, the Initial condition setting parameter behaves as Output.

Command-Line Information

Parameter: InitialConditionSetting
Type: string
Value: 'State (most efficient)' | 'Output' | 'Compatibilty'
Default: 'Output'

Sample time (-1 for inherited)

Enter the discrete interval between sample time hits.

Settings

Default: 1

By default, the block uses a discrete sample time of 1. To set a different sample time, enter another discrete value, such as 0.1.

See also Specify Sample Time in the online documentation for more information.

Tips

  • Do not specify a sample time of 0. This value specifies a continuous sample time, which the Discrete-Time Integrator block does not support.

  • Do not specify a sample time of inf or NaN because these values are not discrete.

  • If you specify -1 to inherit the sample time from an upstream block, verify that the upstream block uses a discrete sample time. For example, the Discrete-Time Integrator block cannot inherit a sample time of 0.

Command-Line Information

Parameter: SampleTime
Type: string
Value: '1'
Default: '1'

Limit output

Limit the block's output to a value between the Lower saturation limit and Upper saturation limit parameters.

Settings

Default: Off

On

Limit the block's output to a value between the Lower saturation limit and Upper saturation limit parameters.

Off

Do not limit the block's output to a value between the Lower saturation limit and Upper saturation limit parameters.

Dependencies

This parameter enables Upper saturation limit.

This parameter enables Lower saturation limit.

Command-Line Information

Parameter: LimitOutput
Type: string
Value: 'off' | 'on'
Default: 'off'

Upper saturation limit

Specify the upper limit for the integral.

Settings

Default: inf

Minimum: value of Output minimum parameter

Maximum: value of Output maximum parameter

Dependencies

Limit output enables this parameter.

Command-Line Information

Parameter: UpperSaturationLimit
Type: scalar or vector
Value: 'inf'
Default: 'inf'

Lower saturation limit

Specify the lower limit for the integral.

Settings

Default: -inf

Minimum: value of Output minimum parameter

Maximum: value of Output maximum parameter

Dependencies

Limit output enables this parameter.

Command-Line Information

Parameter: LowerSaturationLimit
Type: scalar or vector
Value: '-inf'
Default: '-inf'

Show saturation port

Add a saturation output port to the block.

Settings

Default: Off

On

Add a saturation output port to the block.

Off

Do not add a saturation output port to the block.

Command-Line Information

Parameter: ShowSaturationPort
Type: string
Value: 'off' | 'on'
Default: 'off'

Show state port

Add an output port to the block for the block's state.

Settings

Default: Off

On

Add an output port to the block for the block's state.

Off

Do not add an output port to the block for the block's state.

Command-Line Information

Parameter: ShowStatePort
Type: string
Value: 'off' | 'on'
Default: 'off'

Ignore limit and reset when linearizing

Cause Simulink linearization commands to treat this block as not resettable and as having no limits on its output, regardless of the settings of the block reset and output limitation options.

Settings

Default: Off

On

Cause Simulink linearization commands to treat this block as not resettable and as having no limits on its output, regardless of the settings of the block reset and output limitation options.

Off

Do not cause Simulink linearization commands to treat this block as not resettable and as having no limits on its output, regardless of the settings of the block reset and output limitation options.

Tips

Ignoring the limit and resetting allows you to linearize a model around an operating point. This point may cause the integrator to reset or saturate.

Command-Line Information

Parameter: IgnoreLimit
Type: string
Value: 'off' | 'on'
Default: 'off'

Lock output data type setting against changes by the fixed-point tools

Select to lock the output data type setting of this block against changes by the Fixed-Point Tool and the Fixed-Point Advisor.

Settings

Default: Off

On

Locks the output data type setting for this block.

Off

Allows the Fixed-Point Tool and the Fixed-Point Advisor to change the output data type setting for this block.

Command-Line Information

Parameter: LockScale
Type: string
Value: 'off' | 'on'
Default: 'off'

See Also

For more information, see Use Lock Output Data Type Setting.

Integer rounding mode

Specify the rounding mode for fixed-point operations.

Settings

Default: Floor

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.

Command-Line Information

Parameter: RndMeth
Type: string
Value: 'Ceiling' | 'Convergent' | 'Floor' | 'Nearest' | 'Round' | 'Simplest' | 'Zero'
Default: 'Floor'

See Also

For more information, see Rounding in the Fixed-Point Designer documentation.

Saturate on integer overflow

Specify whether overflows saturate.

Settings

Default: Off

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.

Off

Overflows wrap to the appropriate value that is representable by the data type.

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

Tips

  • Consider selecting this check box when your model has 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 avoid overspecifying how a block handles out-of-range signals. For more information, see Checking 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.

Command-Line Information

Parameter: SaturateOnIntegerOverflow
Type: string
Value: 'off' | 'on'
Default: 'off'

State name

Use this parameter to assign a unique name to each state.

Settings

Default: ' '

  • If left blank, no name is assigned.

Tips

  • A valid identifier starts with an alphabetic or underscore character, followed by alphanumeric or underscore characters.

  • The state name applies only to the selected block.

Dependency

This parameter enables State name must resolve to Simulink signal object when you click the Apply button.

For more information, see States in the Simulink Coder documentation.

Command-Line Information

Parameter: StateIdentifier
Type: string
Value: ' '
Default: ' '

State name must resolve to Simulink signal object

Require that state name resolve to Simulink signal object.

Settings

Default: Off

On

Require that state name resolve to Simulink signal object.

Off

Do not require that state name resolve to Simulink signal object.

Dependencies

State name enables this parameter.

Selecting this check box disables Code generation storage class.

Command-Line Information

Parameter: StateMustResolveToSignalObject
Type: string
Value: 'off' | 'on'
Default: 'off'

Package

Select a package that defines the custom storage class you want to apply.

Settings

Default: ---None---

---None---

Sets internal storage class attributes.

mpt

Applies the built-in mpt package.

Simulink

Applies the built-in Simulink package.

Dependencies

If you have defined any packages of your own, click Refresh. This action adds all user-defined packages on your search path to the package list.

Code generation storage class

Select state storage class.

Settings

Default: Auto

Auto

Auto is the appropriate storage class for states that you do not need to interface to external code.

ExportedGlobal

State is stored in a global variable

ImportedExtern

model_private.h declares the state as an extern variable.

ImportedExternPointer

model_private.h declares the state as an extern pointer.

Dependencies

State name enables this parameter.

Setting this parameter to ExportedGlobal, ImportedExtern, or ImportedExternPointer enables Code generation storage type qualifier.

Command-Line Information

Command-Line Information

Parameter: StateStorageClass
Type: string
Value: 'Auto' | 'ExportedGlobal' | 'ImportedExtern' | 'ImportedExternPointer'
Default: 'Auto'

Code generation storage class

Select custom storage class for state.

Settings

Default: Auto

Auto

Auto is the appropriate storage class for states that you do not need to interface to external code.

SimulinkGlobal

model_P initializes the state to its corresponding value in the workspace.

ExportedGlobal

State is stored in a global variable

ImportedExtern

model_private.h declares the state as an extern variable.

ImportedExternPointer

model_private.h declares the state as an extern pointer.

Default

A non-editable placeholder storage class is created.

BitField

A struct declaration is created that embeds Boolean data.

Volatile

Volatile type qualifier is used in state declaration.

ExportToFile

Header (.h) file containing global variable declarations is generated with user-specified name.

ImportFromFile

Predefined header (.h) files containing global variable declarations are included.

FileScope

A static qualifier is generated in front of the state declaration to make the state visible only to the current file.

Struct

A struct declaration is created to encapsulate parameter or signal object data.

StructVolatile

Volatile type qualifier is used in struct declaration.

GetSet

Supports specialized function calls to read and write memory.

Dependencies

State name enables this parameter.

The list of valid storage classes differs based on the Package selection.

Setting this parameter to ExportedGlobal, ImportedExtern, or ImportedExternPointer enables Code generation storage type qualifier.

See Also

State Storage Classes in the Simulink Coder documentation.

Code generation storage type qualifier

Specify the Simulink Coder storage type qualifier.

Settings

Default: ' '

If left blank, no qualifier is assigned.

Dependency

Setting Code generation storage class to ExportedGlobal, ImportedExtern, or ImportedExternPointer enables this parameter.

Command-Line Information

Parameter: RTWStateStorageTypeQualifier
Type: string
Value: ' '
Default: ' '

Output minimum

Lower value of the output range that Simulink checks.

Settings

Default: [] (unspecified)

Specify this number as a finite, real, double, scalar value.

    Note:   If you specify a bus object as the data type for this block, do not set the minimum value for bus data on the block. Simulink ignores this setting. Instead, set the minimum values for bus elements of the bus object specified as the data type. For information on the Minimum parameter for a bus element, see Simulink.BusElement.

Simulink uses the minimum to perform:

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

Command-Line Information

Parameter: OutMin
Type: string
Value: '[ ]'
Default: '[ ]'

Output maximum

Upper value of the output range that Simulink checks.

Settings

Default: [] (unspecified)

Specify this number as a finite, real, double, scalar value.

    Note:   If you specify a bus object as the data type for this block, do not set the maximum value for bus data on the block. Simulink ignores this setting. Instead, set the maximum values for bus elements of the bus object specified as the data type. For information on the Maximum parameter for a bus element, see Simulink.BusElement.

Simulink uses the maximum value to perform:

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

Command-Line Information

Parameter: OutMax
Type: string
Value: '[ ]'
Default: '[ ]'

Output data type

Specify the output data type.

Settings

Default: Inherit: Inherit via internal rule

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

Use data type of the driving block.

double

Output data type is double.

single

Output data type is single.

int8

Output data type is int8.

uint8

Output data type is uint8.

int16

Output data type is int16.

uint16

Output data type is uint16.

int32

Output data type is int32.

uint32

Output data type is uint32.

fixdt(1,16,0)

Output data type is fixed point fixdt(1,16,0).

fixdt(1,16,2^0,0)

Output data type is fixed point fixdt(1,16,2^0,0).

<data type expression>

Use a data type object, for example, Simulink.NumericType.

Command-Line Information

Parameter: OutDataTypeStr
Type: string
Value: 'Inherit: Inherit via internal rule' | 'Inherit: Inherit via back propagation' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)'
Default: 'Inherit: Inherit via internal rule'

See Also

For more information, see Specify Block Output Data Types.

Mode

Select the category of data to specify.

Settings

Default: Inherit

Inherit

Inheritance rules for data types. Selecting Inherit enables a second menu/text box to the right. Select one of the following choices:

  • Inherit via internal rule (default)

  • Inherit via back propagation

Built in

Built-in data types. Selecting Built in enables a second menu/text box to the right. Select one of the following choices:

  • double (default)

  • single

  • int8

  • uint8

  • int16

  • uint16

  • int32

  • uint32

Fixed point

Fixed-point data types.

Expression

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

Dependency

Clicking the Show data type assistant button enables this parameter.

Command-Line Information

Parameter: OutDataTypeStr
Type: string
Value: 'Inherit: Inherit via internal rule' | 'Inherit: Inherit via back propagation' | 'double' | 'single' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)'
Default: 'Inherit: Inherit via internal rule'

See Also

See Specify Data Types Using Data Type Assistant.

Data type override

Specify data type override mode for this signal.

Settings

Default: Inherit

Inherit

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.

Off

Ignores the data type override setting of its context and uses the fixed-point data type specified for the signal.

Tip

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.

Dependency

This parameter appears only when the Mode is Built in or Fixed point.

Signedness

Specify whether you want the fixed-point data as signed or unsigned.

Settings

Default: Signed

Signed

Specify the fixed-point data as signed.

Unsigned

Specify the fixed-point data as unsigned.

Dependencies

Selecting Mode > Fixed point enables this parameter.

See Also

For more information, see Specifying a Fixed-Point Data Type.

Word length

Specify the bit size of the word that holds the quantized integer.

Settings

Default: 16

Minimum: 0

Maximum: 32

Dependencies

Selecting Mode > Fixed point enables this parameter.

See Also

For more information, see Specifying a Fixed-Point Data Type.

Scaling

Specify the method for scaling your fixed-point data to avoid overflow conditions and minimize quantization errors.

Settings

Default: Best precision

Binary point

Specify binary point location.

Slope and bias

Enter slope and bias.

Best precision

Specify best-precision values.

Dependencies

Selecting Mode > Fixed point enables this parameter.

Selecting Binary point enables:

  • Fraction length

  • Calculate Best-Precision Scaling

Selecting Slope and bias enables:

  • Slope

  • Bias

  • Calculate Best-Precision Scaling

See Also

For more information, see Specifying a Fixed-Point Data Type.

Fraction length

Specify fraction length for fixed-point data type.

Settings

Default: 0

Binary points can be positive or negative integers.

Dependencies

Selecting Scaling > Binary point enables this parameter.

See Also

For more information, see Specifying a Fixed-Point Data Type.

Slope

Specify slope for the fixed-point data type.

Settings

Default: 2^0

Specify any positive real number.

Dependencies

Selecting Scaling > Slope and bias enables this parameter.

See Also

For more information, see Specifying a Fixed-Point Data Type.

Bias

Specify bias for the fixed-point data type.

Settings

Default: 0

Specify any real number.

Dependencies

Selecting Scaling > Slope and bias enables this parameter.

See Also

For more information, see Specifying a Fixed-Point Data Type.

Examples

The sldemo_fuelsyssldemo_fuelsys model uses a Discrete-Time Integrator block in the fuel_rate_control/airflow_calc subsystem. This block uses the Forward Euler integration method.

When the Switch block feeds a nonzero value into the Discrete-Time Integrator block, integration occurs. Otherwise, integration does not occur.

For more information, see the model descriptionmodel description.

Characteristics

Direct Feedthrough

Yes, of the reset and external initial condition source ports. The input has direct feedthrough for every integration method except Forward Euler and accumulation Forward Euler.

Sample Time

Specified in the Sample time parameter

Scalar Expansion

Yes, of parameters

States

Inherited from driving block and parameter

Dimensionalized

Yes

Multidimensionalized

No

Zero-Crossing Detection

No

See Also

Integrator

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