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Variable Integer Delay

Delay input signal by variable sample period

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  • Variable Integer Delay block

Libraries:
Simulink / Discrete

Description

The Variable Integer Delay block is a variant of the Delay block that has the source of the delay length set to Input port, by default.

Examples

Using Buses with Legacy Functions Having Structure Arguments

Using Buses with Legacy Functions Having Structure Arguments

Use the Legacy Code Tool to integrate legacy C functions with structure arguments using Simulink® buses.

Ports

Input

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Input data signal delayed according to parameters settings.

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

Delay length specified as inherited from an input port. Enabled when you select the Delay length: Source parameter as Input port.

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

Enable signal that enables or disables execution of the block. To create this port, select the Show enable port parameter.

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

External signal that resets execution of the block to the initial condition. To create this port, select the External reset parameter.

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

Initial condition specified as inherited from an input port. Enabled when you select the Initial Condition: Source parameter as Input port.

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

Output

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Output signal that is the input signal delayed by the length of time specified by the parameter Delay length. The initial value of the output signal depends on several conditions. See Initial Block Output.

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

Parameters

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Main

Specify whether to enter the delay length directly on the dialog box (fixed delay) or to inherit the delay from an input port (variable delay).

  • If you set Source to Dialog, enter the delay length in the edit field under Value.

  • If you set Source to Input port, verify that an upstream signal supplies a delay length for the d input port. You can also specify its maximum value by specifying the parameter Upper limit.

Specify the scalar delay length as a real, non-negative integer. An out-of-range or non-integer value in the dialog box (fixed delay) returns an error. An out-of-range value from an input port (variable delay) casts it into the range. A non-integer value from an input port (variable delay) truncates it to the integer.

Programmatic Use

Block Parameter: DelayLengthSource
Type: character vector
Values: 'Dialog' | 'Input port' |
Default: 'Dialog'
Block Parameter: DelayLength
Type: character vector
Values: scalar
Default: '2'
Block Parameter: DelayLengthUpperLimit
Type: character vector
Values: scalar
Default: '100'

Specify whether to enter the initial condition directly on the dialog box or to inherit the initial condition from an input port.

  • If you set Source to Dialog, enter the initial condition in the edit field under Value.

  • If you set Source to Input port, verify that an upstream signal supplies an initial condition for the x0 input port.

Simulink® converts offline the data type of Initial condition to the data type of the input signal u using a round-to-nearest operation and saturation.

Note

When State name must resolve to Simulink signal object is selected on the State Attributes pane, the block copies the initial value of the signal object to the Initial condition parameter. However, when the source for Initial condition is Input port, the block ignores the initial value of the signal object.

Programmatic Use

Block Parameter: InitialConditionSource
Type: character vector
Values: 'Dialog' | 'Input port' |
Default: 'Dialog'
Block Parameter: InitialCondition
Type: character vector
Values: scalar
Default: '0.0'

Specify whether the block performs sample- or frame-based processing:

  • Columns as channels (frame based) — Treat each column of the input as a separate channel (frame-based processing).

    Note

    Frame-based processing requires a DSP System Toolbox™ license.

    For more information, see Sample- and Frame-Based Concepts (DSP System Toolbox).

  • Elements as channels (sample based) — Treat each element of the input as a separate channel (sample-based processing).

Use Input processing to specify whether the block performs sample- or frame-based processing. For more information about these two processing modes, see Sample- and Frame-Based Concepts (DSP System Toolbox).

Programmatic Use

Block Parameter: InputProcessing
Type: character vector
Values: 'Columns as channels (frame based)' | 'Elements as channels (sample based)'
Default: 'Elements as channels (sample based)'

Select to use a circular buffer for storing the state in simulation and code generation. Otherwise, an array buffer stores the state.

Using a circular buffer can improve execution speed when the delay length is large. For an array buffer, the number of copy operations increases as the delay length goes up. For a circular buffer, the number of copy operations is constant for increasing delay length.

If one of the following conditions is true, an array buffer always stores the state because a circular buffer does not improve execution speed:

  • For sample-based signals, the delay length is 1.

  • For frame-based signals, the delay length is no larger than the frame size.

Programmatic Use

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

Select to increase the delay length from zero to the lower limit for the Input processing mode:

  • For sample-based signals, increase the minimum delay length to 1.

  • For frame-based signals, increase the minimum delay length to the frame length.

Selecting this check box prevents direct feedthrough from the input port, u, to the output port. However, this check box cannot prevent direct feedthrough from the initial condition port, x0, to the output port.

Dependency

To enable this parameter, set Delay length: Source to Input port.

Programmatic Use

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

Select to remove code that checks for out-of-range delay length.

Check BoxResultWhen to Use

Selected

Generated code does not include conditional statements to check for out-of-range delay length.

For code efficiency

Cleared

Generated code includes conditional statements to check for out-of-range delay length.

For safety-critical applications

Dependency

To enable this parameter, set Delay length: Source to Input port.

Programmatic Use

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

Specify whether to produce a warning or error when the input d is less than the lower limit or greater than the Delay length: Upper limit. The lower limit depends on the setting for Prevent direct feedthrough.

  • If the check box is cleared, the lower limit is zero.

  • If the check box is selected, the lower limit is 1 for sample-based signals and frame length for frame-based signals.

Options for the diagnostic include:

  • None — Simulink software takes no action.

  • Warning — Simulink software displays a warning and continues the simulation.

  • Error — Simulink software terminates the simulation and displays an error.

Dependency

To enable this parameter, set Delay length: Source to Input port.

Programmatic Use

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

Select to control execution of this block with an enable port. The block is considered enabled when the input to this port is nonzero, and is disabled when the input is 0. The value of the input is checked at the same time step as the block execution.

Programmatic Use

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

Specify the trigger event to use to reset the states to the initial conditions.

Reset ModeBehavior
NoneNo reset
RisingReset on a rising edge
FallingReset on a falling edge
EitherReset on either a rising or falling edge
Level

Reset in either of these cases:

  • When the reset signal is nonzero at the current time step

  • When the reset signal value changes from nonzero at the previous time step to zero at the current time step

Level holdReset when the reset signal is nonzero at the current time step

Programmatic Use

Block Parameter: ExternalReset
Type: character vector
Values: 'None' | 'Rising' | 'Falling' | 'Either' | 'Level' | 'Level hold'
Default: 'None'

Specify the time interval between samples. To inherit the sample time, set this parameter to -1. This block supports discrete sample time, but not continuous sample time.

Programmatic Use

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

State Attributes

Use this parameter to assign a unique name to the block state. The default is ' '. When this field is blank, no name is assigned. When using this parameter, remember these considerations:

  • 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.

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

For more information, see C Data Code Interface Configuration for Model Interface Elements (Simulink Coder).

Programmatic Use

Block Parameter: StateName
Type: character vector
Values: unique name
Default: ''

Select this check box to require that the state name resolves to a Simulink signal object.

Dependencies

To enable this parameter, specify a value for State name. This parameter appears only if you set the model configuration parameter Signal resolution to a value other than None.

Programmatic Use

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

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

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

Version History

Introduced in R2012b

See Also

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