Simulink Function - Define a function using Simulink blocks - Simulink (original) (raw)
Define a function using Simulink blocks
Libraries:
Simulink / User-Defined Functions
Description
A Simulink Function block is a Subsystem block preconfigured to enable implementation of a function using Simulink® blocks. To define and call a function using a Simulink Function block:
- Specify the function prototype, which includes the function name and input and output arguments, for example,
y = f(u). - Implement function behavior using blocks from the Simulink library.
- Configure your Simulink Function block to be called and reused anywhere in the model hierarchy.
When a function is called, the caller sends data through input arguments to the function, executes the function based on the implemented behavior, and then receives data back from the function through output arguments.
For more information, see Simulink Functions Overview.
Specify Function Prototype
The function prototype is separate from the implementation of the function. It specifies the input and output arguments and how the function should be called from other blocks in the model hierarchy. Each input or output argument specified in the function prototype is represented by an Argument Inport block or Argument Outport block, respectively. You can edit the function prototype by double-clicking the text displayed on the block.
Configure Simulink Function Block
To configure a Simulink Function block, open the block parameters of the Trigger block located inside of theSimulink Function block.
- Function name – Specify the function name for the Simulink Function block.
- Function visibility – Select the scope visibility of the function.
If Function visibility is set toport, you can also specify these parameters:- Execute function call asynchronously – Specify whether the function executes synchronously or asynchronously.
- Scope to port – Specify the name of the exporting function port.
Model Considerations
When using a Simulink Function block, consider whether your model requires persistence of states between functions calls or a continuous sample time.
- Persistence of state between function calls – If a Simulink Function block contains any blocks with state (for example,Unit Delay or Memory blocks), then their state values are persistent between calls to the function. If there are multiple calls to that function, the state values are also persistent between the calls originating from different callers.
- Unable to inherit continuous sample time – A Simulink Function block cannot inherit a continuous sample time.
Examples
Ports
Input
Placing an Inport block in a subsystem block adds an external input port to the block. The port label matches the name of theInport block.
Use Inport blocks to receive signals from the local environment.
Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | image | struct
An Argument Inport block in a subsystem block provides an input port corresponding to an input argument. A port is not displayed on the subsystem block.
Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | image | struct
Output
Placing an Outport block in a subsystem block adds an output port from the block. The port label on the subsystem block is the name of the Outport block.
Use Outport blocks to send signals to the local environment.
Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | image | struct
An Argument Outport block in a subsystem block provides an output port corresponding to an output argument. A port is not displayed on the subsystem block.
Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | image | struct
Parameters
Main
Select how to display port labels on the Subsystem block icon.
none— Do not display port labels.FromPortIcon— If the corresponding port icon displays a signal name, display the signal name on the Subsystem block. Otherwise, display the port block name or the port number if the block name is a default name.FromPortBlockName— Display the name of the corresponding port block on the Subsystem block.SignalName— If the signal connected to the port is named, display the name of the signal on the Subsystem block. Otherwise, display the name of the corresponding port block.
For port label editing on Subsystem blocks, see Edit Port Labels on Subsystem Blocks.
Programmatic Use
To set the block parameter value programmatically, use the set_param function.
| Parameter: | ShowPortLabels | ||
|---|---|---|---|
| Values: | 'FromPortIcon' (default) | 'FromPortBlockName' | 'SignalName' | 'none' |
Control user access to the contents of the subsystem.
ReadWrite— Enable opening and modification of subsystem contents.ReadOnly— Enable opening but not modification of the subsystem. If the subsystem resides in a block library, you can create and open links to the subsystem and can make and modify local copies of the subsystem but cannot change the permissions or modify the contents of the original library instance.NoReadOrWrite— Disable opening or modification of subsystem. If the subsystem resides in a library, you can create links to the subsystem in a model but cannot open, modify, change permissions, or create local copies of the subsystem.
You do not receive a response if you attempt to view the contents of a subsystem whose Read/Write permissions parameter is set to NoReadOrWrite. For example, when double-clicking such a subsystem, the software does not open the subsystem and does not display any messages.
Programmatic Use
To set the block parameter value programmatically, use the set_param function.
| Parameter: | Permissions | |
|---|---|---|
| Values: | 'ReadWrite' (default) | 'ReadOnly' | 'NoReadOrWrite' |
Enter the name of a function to be called if an error occurs while the software executes the subsystem.
The software passes two arguments to the function: the handle of the subsystem and a character vector that specifies the error type. If no function is specified, the software displays a generic error message if executing the subsystem causes an error.
Programmatic Use
To set the block parameter value programmatically, use the set_param function.
| Parameter: | ErrorFcn |
|---|---|
| Values: | '' (default) | function name in quotes |
| Data Types: | char | string |
Select whether to resolve names of workspace variables referenced by this subsystem.
For more information, see Symbol Resolution and Symbol Resolution Process.
All— Resolve all names of workspace variables used by this subsystem, including those used to specify block parameter values and Simulink data objects (for example, Simulink.Signal objects).ExplicitOnly— Resolve only names of workspace variables used to specify block parameter values, data store memory (where no block exists), signals, and states marked as “must resolve”.None— Do not resolve any workspace variable names.
Programmatic Use
To set the block parameter value programmatically, use the set_param function.
| Parameter: | PermitHierarchicalResolution | |
|---|---|---|
| Values: | 'All' (default) | 'ExplicitOnly' | 'None' |
Note
To configure the scope visibility and synchronicity of a Simulink Function block, open the block parameters of the Trigger block located inside of the Simulink Function block.
Block Characteristics
| Data Types | Booleana | busa | doublea | enumerateda | fixed pointa | halfa | imagea | integera | singlea | stringa |
|---|---|---|---|---|---|---|---|---|---|
| Direct Feedthrough | no | ||||||||
| Multidimensional Signals | yesa | ||||||||
| Variable-Size Signals | no | ||||||||
| Zero-Crossing Detection | no | ||||||||
| a Actual data type or capability support depends on block implementation. |
Extended Capabilities
Actual code generation support depends on block implementation.
Actual data type support depends on block implementation.
Version History
Introduced in R2014b
Starting in R2024a, you can define the variant control variables of aSimulink Function block with update diagram activation time in the mask or model workspace.
If scoped to different ports, function names of Simulink functions at the model root level do not have to be unique.
Starting in R2022b, when you select a Simulink Function block whose related Function Caller block is in a referenced model, both theFunction Caller block and the Model block of the referenced model are highlighted.
Starting in R2022b, you can specify a Simulink function to be executed asynchronously by selecting the newExecute function call asynchronously parameter in theTrigger block inside of the Simulink Function block and in the Function Caller block.
A new port-scoped visibility option for the Simulink Function block is added for R2022a. To create a port-scoped Simulink Function block, set the Function visibility parameter of the Trigger block inside theSimulink Function block to port and enter the port name in the Scope to port field. Use port-scoped Simulink Function blocks to implement functions called through exporting function ports created by Function Element blocks. See Model Client and Server Components Using Function Ports.
See Also
Blocks
- Argument Inport | Argument Outport | Trigger | Function Caller | MATLAB Function | Chart (Stateflow) | Function-Call Subsystem | Inport | Outport