Parameter Writer

Write to block parameter or model workspace variable

• 

Libraries:
Simulink / Signal Routing

Description

The Parameter Writer block changes block parameter values by writing to one of the following:

• A parameter of a block that is tunable during simulation

• An instance parameter that belongs to a Model block that references a model

• A masked subsystem parameter

• A model workspace variable

A block with a parameter that can be written by a Parameter Writer block is called a parameter owner block. For the Parameter Writer block to find the supported parameters of a parameter owner block, the supported parameters must be enabled.

Use the Parameter Writer block with the Initialize Function, Reinitialize Function, and Reset Function blocks to respond to events. For example, an event could be reading the value from a hardware sensor and then updating a block parameter based on the sensor value.

For more information about using the Parameter Writer block, see Initialize and Reset Parameter Values.

Otherwise, a Parameter Writer block must be in the same task as either:

• The block whose parameter is directly written by the Parameter Writer block, which could be a built-in block such as a Gain block, a Model block, a masked subsystem block, or a User-Defined Functions block such as an S-Function block

• The block whose parameter is indirectly written through a model workspace variable

To write to a model workspace variable, mask parameter, or Model block instance parameter with a Parameter Writer block, the model workspace variable, mask parameter, or Model block instance parameter must be used by a parameter owner block or C MEX S-function with run-time tunable parameters.

For a Parameter Writer block in a masked subsystem, the Parameter Writer block and corresponding parameter owner block must have the same immediate parent masked subsystem.

When a Parameter Writer block writes to an instance parameter with storage class set to Model default, the code generator uses the default configuration for Model parameter arguments when generating code for the parameter. See Specify Instance-Specific Parameter Values for Reusable Referenced Model (Simulink Coder).

When you create a library block with a Parameter Writer block, you must also include the corresponding parameter owner block in the library block.

Identify Parameter Owner Blocks

You can determine whether a block is a supported parameter owner block by the value of the IsParamOwnerBlock block parameter. Use the get_param function with the block name or handle, blk, and the IsParamOwnerBlock block parameter.

get_param(blk,'IsParamOwnerBlock')

The function returns 'on' if the block is a supported parameter owner block and 'off' otherwise.

A Parameter Writer block and the parameter owner block of the value that the block writes constitute a set of related blocks. You can select a Parameter Writer block to highlight the related parameter owner block or vice versa. When a related block is highlighted, blocks in the current model that contain the related block are also highlighted. For example, an Initialize Function block is highlighted when it contains a Parameter Writer block that is related to the selected block. The blocks that are highlighted in the model canvas are also highlighted in the miniature map.

To show a related block in an open diagram or new tab, pause on the ellipsis that appears after selection. Then, select the Related Blocks button from the action bar. Window focus goes to the open diagram or new tab that shows the related block.

Examples

Use Parameter Writer Block to Change Parameter of Block Inside Referenced Model

Use a Parameter Writer block inside an Initialize Function block to change the Gain parameter of a Gain block in a referenced model.The Gain parameter is configured to change at every instance of the model.

Open Live Script

Use Parameter Writer Block to Change Block Parameters

Use the Parameter Writer block to change the values of block parameters.

Open Live Script

Limitations

A Parameter Writer block cannot be placed in a Simulink^® function.

Ports

Input

In — Parameter value

scalar | vector

Parameter value written by the block.

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

Parameters

Validate parameter — Option to validate parameter during normal mode simulation

on (default) | off

Since R2023a

Locally enable parameter validation for this block.

When parameter validation is disabled for a Paramer Writer block, normal mode simulation of the block is faster.

Tips

To globally enable or disable parameter validation for Parameter Writer blocks, use the Parameter Writer block validation configuration parameter.

Dependencies

To disable parameter validation for this block, the block must not directly or indirectly change the value of a Model block instance parameter. For example, the block must not change the value of a model workspace variable or mask parameter that specifies the value of a Model block instance parameter.

Programmatic Use

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

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

Example: set_param(gcb,'IsParameterValidationOn','off')

Access model workspace parameter — Option to write to model workspace variable instead of block parameter

off (default) | on

Select this parameter to write to a model workspace variable, as specified by the Model workspace parameter name parameter.

Clear this parameter to write to a tunable block parameter, model instance parameter, or masked subsystem parameter, as specified by the Parameter owner block parameter.

Programmatic Use

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

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

Example: set_param(gcb,'AccessWorkspaceVariable','on')

Model workspace parameter name — Name of model workspace variable

no default

Specify the name of the model workspace variable whose value this block writes.

Dependencies

To enable this parameter, select the Access model workspace parameter parameter.

Programmatic Use

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

Parameter:	WorkspaceVariableName
Values:	'' (default) | character vector | string scalar

Example: set_param(gcb,'WorkspaceVariableName','var')

Parameter owner block — Block path of parameter owner block and name of block parameter

no default

Specify the block path of the parameter owner block and the name of the parameter whose value this block writes.

The Parameter Owner Selector Tree provides the writable parameters in a hierarchical tree list. Expand the nodes on the path to the parameter owner block. Then, select the parameter under the parameter owner block.

Tips

If the name of a parameter owner block contains a slash (/), the slash appears as two slashes (//) in the Parameter Writer block parameters. This notation distinguishes the slash in the block name itself from slashes that separate names at different levels of the model hierarchy.

Dependencies

To enable this parameter, clear the Access model workspace parameter parameter.

Programmatic Use

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

First, specify the block path of a parameter owner block using the ParameterOwnerBlock parameter.

Parameter:	ParameterOwnerBlock
Values:	'' (default) | character vector | string scalar
Data Types:	char | string

Example: set_param(gcb,'ParameterOwnerBlock','mymodel/Gain1')

Then, specify the programmatic name of a block parameter of the parameter owner block using the ParameterName parameter.

Parameter:	ParameterName
Values:	'' (default) | character vector | string scalar

Example: set_param(gcb,'ParameterName','Gain')

Block Characteristics

Data Types	Boolean | bus | double | enumerated | fixed point | integer | single
Direct Feedthrough	no
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™.

Version History

R2023a: Disable parameter validation during normal mode simulation

Optionally, disable parameter validation that occurs during normal mode simulation for Parameter Writer blocks. When parameter validation is disabled for a Parameter Writer block, normal mode simulation of the block is faster.

To locally enable or disable parameter validation for a Parameter Writer block, use the Validate parameter block parameter.

To globally enable or disable parameter validation for Parameter Writer blocks, use the Parameter Writer block validation configuration parameter.