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Data Store Memory

Define data store

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  • Library:

  • Simulink / Signal Routing

  • Data Store Memory block

Description

TheData Store Memoryblock defines and initializes a named shared data store, which is a memory region usable byData Store ReadandData Store Writeblocks that specify the same data store name.

The location of theData Store Memoryblock that defines a data store determines whichData Store ReadandData Store Writeblocks can access the data store:

  • If theData Store Memoryblock is in thetop-level system,Data Store ReadandData Store Writeblocks anywhere in the model can access the data store.

  • If theData Store Memoryblock is in asubsystem,Data Store ReadandData Store Writeblocks in the same subsystem or in any subsystem below it in the model hierarchy can access the data store.

Data Store ReadorData Store Writeblocks cannot access aData Store Memoryblock that is either in a model that contains aModelblock or in a referenced model.

Do not include aData Store Memoryblock in a For Each subsystem.

Obtaining correct results from data stores requires ensuring that data store reads and writes occur in the expected order. For details, see:

You can useSimulink.Signalobjects in addition to, or instead of,Data Store Memoryblocks to define data stores. A data store defined in thebaseworkspace with a signal object is aglobaldata store. Global data stores are accessible to every model, including all referenced models. See数据存储for more information.

You can select aData Store Read,Data Store Write, orData Store Memoryblock to highlight blocks related to it. To show a related block in an open diagram or new tab, pause on the ellipsis that appears after selection. Then, selectRelated BlocksRelated Blocks buttonfrom the action bar. When multiple blocks correspond to the selected block, a list of related blocks opens. You can filter the list of related blocks by entering a search term in the text box. After you select a related block from the list, window focus goes to the open diagram or new tab that shows the related block.

Parameters

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Main

Specify a name for the data store you are defining with this block.Data Store ReadandData Store Writeblocks with the same name can read from, and write to, the data store initialized by this block. The name can represent aData Store Memoryblock or a sign object defined to be a data store.

Programmatic Use

Block Parameter:DataStoreName
Type: character vector
Values:'A' | ...
Default:'A'

Rename this data store everywhere theData Store ReadandData Store Writeblocks use it in a model.

Limitations

You cannot useRename Allto rename a data store if you:

  • Use aSimulink.Signalobject in a workspace to control the code generated for the data store

  • Use aSimulink.Signalobject instead of aData Store Memoryblock to define the data store

You must instead rename the correspondingSimulink.Signalobject from Model Explorer. For an example, seeRename Data Store Defined by Signal Object.

List all theData Store ReadandData Store Writeblocks that have the same data store name as the current block, and that are in the current system or in any subsystem below it in the model hierarchy. Clicking a block path displays and highlights that block in your model.

Signal Attributes

Specify the initial value or values of the data store. TheMinimumparameter specifies the minimum value for this parameter, and theMaximum参数指定的最大价值。

If you specify a nonscalar value and setDimensionsto-1(the default), the data store has the same dimensions as the array. Data that you write to the data store (by usingData Store Writeblocks) must have these dimensions.

If you set theDimensionsparameter to a value other than-1,e initial value dimensions must match the dimensions that you specify, unless the initial value is a scalar or a MATLAB®structure. If you specify a scalar, each element of the data store uses the scalar as the initial value. Use this technique to apply the same initial value (the scalar that you specify) to each element without manually matching the dimensions of the initial value with the dimensions of the data store.

To use this block to initialize a nonvirtual bus signal, specify the initial value as a MATLAB structure and set the model configuration parameterUnderspecified initialization detectiontoSimplified. For more information about initializing nonvirtual bus signals using structures, seeSpecify Initial Conditions for Bus Elements.

Programmatic Use

Block Parameter:InitialValue
Type: character vector
Values: scalar | vector | matrix | N-D array
Default:'0'

Specify the minimum value that the block should output. The default value is[](unspecified). This number must be 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 property of a bus element, seeSimulink.BusElement.

金宝app®uses the minimum value to perform:

Programmatic Use

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

Specify the maximum value that the block should output. The default value is[](unspecified). This number must be 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 property of a bus element, seeSimulink.BusElement.

Simulink uses the maximum value to perform:

Programmatic Use

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

Specify the output data type. You can set it to:

  • A rule that inherits a data type (for example,Inherit: auto).

  • The name of a built-in data type (for example,单).

  • The name of a data type object (for example, aSimulink.NumericTypeobject).

  • An expression that evaluates to a data type (for example,fixdt(1,16,0)). Do not specify a bus object as the data type in an expression; useBus: to specify a bus data type.

  • If you have Computer Vision Toolbox™, use the constructor for theSimulink.ImageType(Computer Vision Toolbox)object and specify the properties to describe the image. By default, the data type uses theSimulink.ImageType(480,640,3)expression that represents the rows, columns, and channels of the image respectively.

    • Click theShow data type assistantbuttonto display theData Type Assistant, which helps you set the data type attributes. For more information, seeSpecify Data Types Using Data Type Assistant.

    Programmatic Use

    Block Parameter:OutDataTypeStr
    Type:character vector
    Values:'Inherit: auto' | 'double' | 'single' | 'half' | 'int8' | 'uint8' | 'int16' | 'uint16' | 'int32' | 'uint32' | 'int64' | 'uint64' | 'boolean' | 'fixdt(1,16,0)' | 'fixdt(1,16,2^0,0)' | 'string' | 'Enum: ' | 'Simulink.ImageType(480,640,3)'
    Default:'Inherit: auto'

    Select this parameter to prevent the fixed-point tools from overriding theOutputdata type you specify on the block. For more information, seeUse Lock Output Data Type Setting(Fixed-Point Designer).

    Programmatic Use

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

    Dimensions of the data store. The default value,-1,使您能够设置dimensions of the data store by using theInitial valueparameter. However, in this case, you cannot use scalar expansion with the initial value. You must specify the initial value by using an array that has the dimensions that you want.

    If you use a value other than-1, specify the same dimensions as the dimensions of theInitial valueparameter, unless you specify the initial value as a scalar (for scalar expansion) or a MATLAB structure. If the data store represents an array of buses, and if you use a MATLAB structure for the initial value, you can specify dimensions to initialize the array of buses with this structure.

    Programmatic Use

    Block Parameter:Dimensions
    Type:character vector
    Values:scalar | vector | matrix
    Default:'-1'

    Specify that the data store interpret vector initial values as one-dimensional.

    By default, MATLAB represents vector data as matrices, which have two dimensions. For example, MATLAB represents the vector[1 2 3]as a 1-by-3 matrix.

    When you select this parameter, the data store represents vector data by using only one dimension instead of two. For example, if you specify an initial value of[1 2 3],e data store stores a one-dimensional vector with three elements.

    For more information, seeDetermine the Output Dimensions of Source Blocks.

    Programmatic Use

    Block Parameter:VectorParams1D
    Type: character vector
    Values:'off' | 'on'
    Default:'on'

    Specify the numeric type, real or complex, of the values in the data store.

    Programmatic Use

    Block Parameter:SignalType
    Type:character vector
    Values:'auto' | 'real' | 'complex'
    Default:'auto'

    In a single model reference hierarchy, when you use multipleModelblocks to refer to a model that contains aData Store Memoryblock, by default, each instance of the referenced model (eachModelblock) reads from and writes to a separate copy of the data store. When you selectShare across model instances, instead of interacting with a separate copy, all of the instances read from and write to the same data store.

    When you set the model configuration parameterCode interface packagingtoReusable functionto generate reentrant code from a model (Simulink Coder™), a data store withShare across model instancesselected appears in the code as a global symbol that the generated entry-point functions access directly. For example, a global symbol is a global variable or a field of a global structure variable. Therefore, each call that your code makes to the entry-point functions (each instance of the model) shares the data.

    For an example, seeShare Data Store Between Instances of a Reusable Algorithm. For more information, seeShare Data Among Referenced Model Instances.

    Programmatic Use

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

    Specify that Simulink software, when compiling the model, searches the model and base workspace for aSimulink.Signalobject having the same name, as described inSymbol Resolution. If Simulink does not find such an object, the compilation stops with an error. Otherwise, Simulink compares the attributes of the signal object to the corresponding attributes of the Data Store Memory block. If the block and the object attributes are inconsistent, Simulink halts model compilation and displays an error.

    Programmatic Use

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

    Diagnostics

    Select the diagnostic action to take if the model attempts to read data from a data store to which it has not written data in this time step. See also theDetect read before writediagnostic in theData Store Memory blocksection of theModel Configuration Parameters>Diagnostics>Data Validitypane.

    • None— Produce no response.

    • Warning— Display a warning and continue the simulation.

    • Error— Terminate the simulation and display an error.

    Programmatic Use

    Block Parameter:ReadBeforeWriteMsg
    Type:character vector
    Values:'none' | 'warning' | 'error'
    Default:'warning'

    Select the diagnostic action to take if the model attempts to write data to the data store after previously reading data from it in the current time step. See also theDetect write after readdiagnostic in theData Store Memory blocksection of theModel Configuration Parameters>Diagnostics>Data Validitypane.

    • None— Produce no response.

    • Warning— Display a warning and continue the simulation.

    • Error— Terminate the simulation and display an error.

    Programmatic Use

    Block Parameter:WriteAfterReadMsg
    Type:character vector
    Values:'none' | 'warning' | 'error'
    Default:'warning'

    Select the diagnostic action to take if the model attempts to write data to the data store twice in succession in the current time step. See also theDetect write after writediagnostic in theData Store Memory blocksection of theModel Configuration Parameters>Diagnostics>Data Validitypane.

    • None— Produce no response.

    • Warning— Display a warning and continue the simulation.

    • Error— Terminate the simulation and display an error.

    Programmatic Use

    Block Parameter:WriteAfterWriteMsg
    Type:character vector
    Values:'none' | 'warning' | 'error'
    Default:'warning'

    Logging

    Select this option to save the values of this signal to the MATLAB workspace during simulation. SeeSignal Loggingfor details.

    Programmatic Use

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

    Use this pair of controls, consisting of a list box and an edit field, to specify the name associated with logged signal data.

    Simulink uses the signal name as its logging name by default. To specify a custom logging name, selectCustomfrom the list box and enter the custom name in the adjacent edit field.

    Programmatic Use

    Block Parameter:DataLoggingNameMode
    Type:character vector
    Values:'SignalName' | 'Custom'
    Default:''

    Note

    If you setDataLoggingNameModetoCustom, you must specify the name associated with logged signal data using theDataLoggingNameparameter.

    Block Parameter:DataLoggingName
    Type:character vector
    Values:character vector
    Default:''

    Discard all but the lastNdata points, whereNis the number that you enter in the adjacent edit field. For more information, seeLog Data Stores.

    Programmatic Use

    Block Parameter:DataLoggingMaxPoints
    Type:character vector
    Values:nonzero integer
    Default:'5000'

    Log everyNth data point, whereNis the number that you enter in the adjacent edit field. For example, suppose that your model uses a fixed-step solver with a step size of0.1s. If you select this option and accept the default decimation value (2), Simulink records data points for this signal at times0.0,0.2,0.4, and so on. For more information, seeLog Data Stores.

    Programmatic Use

    Block Parameter:DataLoggingLimitDataPoints
    Type:character vector
    Values:non-zero integer
    Default:'2'

    Model Examples

    Share Data Store Between Instances of a Reusable Algorithm

    Share Data Store Between Instances of a Reusable Algorithm

    To reuse an algorithm, instead of copying and pasting the blocks, you can encapsulate them in a separate model file. Then, you can refer to the model repeatedly with Model blocks. Each Model block is a standalone instance of the algorithm.
    Open Model

    Block Characteristics

    Data Types

    Boolean|bus|double|enumerated|fixed point|half|integer|单|string

    Direct Feedthrough

    yes

    Multidimensional Signals

    yes

    Variable-Size Signals

    no

    Zero-Crossing Detection

    no

    Extended Capabilities

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

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

    Version History

    Introduced before R2006a

    See Also

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