Resettable Delay
Delay input signal by variable sample period and reset with external signal
Libraries:
Simulink /
Discrete
HDL Coder /
Discrete
Description
The Resettable Delay block is a variant of the Delay block that has the source of the
initial condition set to Input port
and the external
reset algorithm set to Rising
, by default.
Ports
Input
u — Data input signal
scalar | vector
Input data signal delayed according to parameters settings.
Data Types: half
| single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
| string
| Boolean
| fixed point
| enumerated
| bus
d — Delay length
scalar
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 — External enable signal
scalar
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 reset — External reset signal
scalar
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
x0 — Initial condition
scalar | vector
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
Port_1 — Output signal
scalar | vector
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
Main
Delay length — Delay length
Dialog
(default) | Input port
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 thed
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' |
Initial condition — Initial condition
Input port
(default) | Dialog
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 thex0
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: 'Input
Port' |
Block Parameter:
InitialCondition |
Type: character vector |
Values: scalar |
Default:
'' |
Input processing — Specify sample- or frame-based processing
Elements as channels (sample based)
(default) | Columns as channels (frame based)
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)' |
Use circular buffer for state — Circular buffer for storing state
off
(default) | on
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' |
Prevent direct feedthrough — Prevent direct feedthrough
off
(default) | on
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' |
Remove delay length check in generated code — Remove delay length out-of-range check
off
(default) | on
Select to remove code that checks for out-of-range delay length.
Check Box | Result | When 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' |
Diagnostic for delay length — Diagnostic checks for delay length
None
(default) | Warning
| Error
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' |
Show enable port — Create enable port
off
(default) | on
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' |
External reset — External state reset
Rising
(default) | None
| Falling
| Either
| Level
| Level hold
Specify the trigger event to use to reset the states to the initial conditions.
Reset Mode | Behavior |
---|---|
None | No reset. |
Rising | Reset on a rising edge. |
Falling | Reset on a falling edge. |
Either | Reset on either a rising or falling edge. |
Level | Reset in either of these cases:
|
Level hold | Reset when the reset signal is nonzero at the current time step |
The reset signal must be a scalar of type single
,
double
, boolean
, or
integer
. Fixed point data types, except for
ufix1
, are not supported.
Programmatic Use
Block Parameter:
ExternalReset |
Type: character vector |
Values:
'None' | 'Rising' |
'Falling' | 'Either' |
'Level' | 'Level
hold' |
Default:
'Rising' |
Sample time (-1 for inherited) — Discrete interval between sample time hits
-1
(default) | scalar
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
State name — Unique name for block state
''
(default) | alphanumeric string
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: '' |
State name must resolve to Simulink signal object — Require state name resolve to a signal object
off
(default) | on
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 |
|
Direct Feedthrough |
|
Multidimensional Signals |
|
Variable-Size Signals |
|
Zero-Crossing Detection |
|
More About
Model Coverage
If you have a Simulink
Coverage™ license, the Resettable Delay block receives decision
coverage if you set the External reset parameter to any option
except for None
, or if you select the Show
enable port parameter. If your model uses a State Control (HDL Coder) block, you cannot
collect coverage for External reset and
Enable ports when the State control
parameter is Synchronous
.
For the External reset parameter, decision coverage measures a true outcome for time steps where the block resets and a false outcome for time steps where the block does not reset. To receive 100% decision coverage, the block must reset for at least one time step and not reset for at least one time step.
For the Show enable port parameter, decision coverage measures a true outcome for time steps where the block is enabled and a false outcome for time steps where the block is not enabled. To receive 100% decision coverage, the block must be enabled for at least one time step and not enabled for at least one time step.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Consider using the Model Discretizer to map these continuous blocks into discrete equivalents that support code generation. From a model, in the Apps tab, under Control Systems, click Model Discretizer.
Generated code relies on
memcpy
ormemset
functions (string.h
) under certain conditions.
HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.
For information about HDL code generation, see the HDL Code Generation section on the Delay page.
Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.
Version History
Introduced in R2012b
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