Trigger
Add trigger or function port to subsystem or model
Libraries:
Simulink /
Ports & Subsystems
HDL Coder /
Ports & Subsystems
Description
The Trigger block adds an external signal or message port to control the execution of a subsystem or a model. To enable this functionality, add this block to a Subsystem block or at the root level of a model that is referenced in a Model block.
Then, configure the Trigger block to execute a subsystem or model:
Once at each time step, when the value of the control signal changes in a way that you specify.
Multiple times during a time step, when the control signal is a function-call event from a Stateflow® chart, Function-Call Generator block, or S-Function block.
Based on messages received at the control port.
Examples
Ports
Output
Port_1 — Value that describes control signal or message payload
scalar | vector | matrix
If the Trigger type is
rising
,
falling
,
either
, or
function-call
, the port outputs a value
that identifies a control signal, returned as a scalar or vector. For
each element of the input signal, the value at a given time step
is:
1
for a signal that causes a rising trigger-1
for a signal that causes a falling trigger2
for a function-call event0
in all other cases
If the Trigger type is
message
, the port outputs data extracted
from message received at the control port.
Dependencies
To enable this port, select Show output port
or select message
from the Trigger type list.
Data Types: double
| int8
Parameters
Main
Trigger type — Select the type of control signal
rising
(default) | falling
| either
| function-call
| message
Select the type of control signal that executes a subsystem or model.
rising
Trigger execution of subsystem or model when the control signal rises from a negative or zero value to a positive value. If the initial value is negative, a rising signal to zero triggers execution.
falling
Trigger execution of subsystem or model when the control signal falls from a positive or a zero value to a negative value. If the initial value is positive, a falling signal to zero triggers execution.
either
Trigger execution of subsystem or model when the control signal is either rising or falling.
function-call
Execute subsystem or model when the control port receives a function-call event from a Stateflow chart, Function-Call Generator block, S-Function block, or Hit Crossing block.
message
Trigger execution of subsystem when a message is available at the control port.
Note
If Trigger type is set to
message
, the block must be placed inside a subsystem.
Programmatic Use
Block Parameter:
TriggerType |
Type: character vector |
Values:
'rising' | 'falling' |
'either' |
'function-call' |
'message' |
Default:
'rising' |
Treat as Simulink function — Create Simulink Function block
off
(default) | on
Select this parameter to create a Simulink Function block by configuring a Subsystem block that is callable with arguments from a function caller. The Trigger block must reside within the subsystem. You can edit the function prototype that displays on the block face to specify input and output arguments for the block.
Clear this parameter to remove the configuration.
Dependencies
To display and enable this parameter, select
function-call
from the
Trigger type list.
Programmatic Use
Block Parameter:
IsSimulinkFunction |
Type: character vector |
Values:
'off' | 'on' |
Default:
'off' |
Execute function call asynchronously — Whether caller request to call function can wait for service execution
off
(default) | on
Specify whether to execute the Simulink Function block asynchronously for a subsystem containing this Trigger port block.
Select this check box to model asynchronous execution where the caller (client) makes a request to call the function (server). The function is executed based on the ordering defined in the Schedule Editor and then returns the output arguments to the caller.
Clear this check box to model synchronous execution where the caller calls the function and the function runs immediately then returns the output arguments to the caller.
Dependencies
To display and enable this parameter, from the Trigger type list, select
function-call
, then select the
Treat as a Simulink Function
parameter. Then, from the Function visibility
list, select port
.
Programmatic Use
Block Parameter:
AsynchronousFunction |
Type: character vector |
Values:
'on' | 'off' |
Default:
'off' |
Function name — Specify function name for Simulink Function block
f
(default) | function name
Specify the function name for a Simulink Function block. Alternatively, you can specify the name by editing the function prototype on the face of the block.
f
Default name for a Simulink Function block.
- function name
Function name that displays on the face of a Simulink Function block.
Dependencies
To display and enable this parameter, select
function-call
from the Trigger type list and select the
Treat as a Simulink Function
check box.
Programmatic Use
Block Parameter:
FunctionName |
Type: character vector |
Values:
'f' | '<function
name>' |
Default:
'f' |
Function visibility — Select scope visibility of function
scoped
(default) | global
| port
Select scope of Simulink Function block within subsystem or model.
scoped
Limit accessibility of function to:
Hierarchic level containing the Simulink Function block and levels below.
One hierarchical level above with qualification.
global
Function accessible from any part of the model hierarchy.
port
Function accessible only through an exporting function port created by a Function Element block.
Dependencies
To display and enable this parameter, select
function-call
from the Trigger type list, then select the
Treat as a Simulink Function
check box.
Programmatic Use
Block Parameter:
FunctionVisibility |
Type: character vector |
Values:
'scoped' | 'global' |
'port' |
Default:
'scoped' |
Scope to port — Specify name of exporting function port
''
(default) | character vector
For a Simulink Function block with port visibility, specify the name of the exporting function port created by a Function Element block through which the function can be called.
Example: 'ServerPort'
Dependencies
To display and enable this parameter, from the Trigger type list, select
function-call
, then select the
Treat as a Simulink Function
check box. Then, from the Function visibility
list, select port
.
Programmatic Use
Block Parameter:
ScopeName |
Type: character vector |
Values:'PortName' |
Default:
'' |
Enable variant condition — Controls activating the variant control (condition)
on
(default) | off
Control activating the variant control (condition) defined with the Variant Control parameter.
Select this parameter to activate variant control of the subsystem. Selecting this parameter:
Enables the Variant control parameter.
Displays a variant badge
on the face of the block indicating that variant conditions are enabled.
Clear this parameter to deactivate variant control of the subsystem.
Dependencies
To display and enable this parameter, select
function-call
from the
Trigger type list and select the
Treat as Simulink function check
box.
Programmatic Use
Block Parameter:
Variant |
Type: character vector |
Values:
'off' | 'on' |
Default:
'on' |
Variant control — Specify variant control (condition) expression
(inherit)
(default) | logical expression
Specify variant control (condition) expression that executes a variant
Simulink Function block when the expression evaluates
to true
.
(inherit)
Default value for variant control. Inherits the variant condition from the corresponding Function Caller blocks in the model. When Variant Control is set as
(inherit)
the value for Generate preprocessor conditionals is inherited automatically from the Function Caller block in the model.- logical expression
A logical (Boolean) expression or a
Simulink.Variant
object representing a logical expression.The function is activated when the expression evaluates to
true
.If you want to generate code for your model, define the variables in the expression as
Simulink.Parameter
objects.
Dependencies
To display and enable this parameter, select
function-call
from the Trigger type list, select the Treat as a Simulink Function check box,
then select the Enable variant condition check
box.
Programmatic Use
Block Parameter:
VariantControl |
Type: character vector |
Values:
'(inherit)' |<logical
expression> | Simulink.Variant
object |
Default:
'(inherit)' |
Generate preprocessor conditionals — Control enclosing variant choices
off
(default) | on
Control enclosing variant choices within C preprocessor conditional statements.
Select this parameter to enclose variant choices within C preprocessor conditional statements (#if) when generating code for an ERT target.
Dependencies
To display and enable this parameter, select the Enable variant condition check box.
Programmatic Use
Block Parameter:
GeneratePreprocessorConditionals |
Type: character vector |
Values:
'off' | 'on' |
Default:
'off' |
States when enabling — Select how to set block state values
held
(default) | reset
| inherit
Select how to set block state values when the subsystem or model is disabled.
held
Leave the block states at their current values.
reset
Reset the block state values.
inherit
Use the
held
orreset
setting from the parent subsystem initiating the function-call. If the parent of the initiator is the model root, the inherited setting isheld
. If the trigger has multiple initiators, set the parents of all initiators to eitherheld
orreset
.
Dependencies
To enable this parameter, select
function-call
from the
Trigger Type list.
This parameter setting applies only if the model explicitly enables and disables the function-call subsystem. For example:
The function-call subsystem resides in an enabled subsystem. In this case, the model enables and disables the function-call subsystem along with the parent subsystem.
The function-call initiator that controls the function-call subsystem resides in an enabled subsystem. In this case, the model enables and disables the function-call subsystem along with the enabled subsystem containing the function-call initiator.
The function-call initiator is a Stateflow event bound to a particular state. See Control Function-Call Subsystems by Using bind Actions (Stateflow).
The function-call initiator is an S-function that explicitly enables and disables the function-call subsystem. See
ssEnableSystemWithTid
for an example.
Programmatic Use
Block Parameter:
StatesWhenEnabling |
Type: character vector |
Values:
'held' | 'reset' |
'inherit' |
Default:
'held' |
Propagate sizes of variable-size signals — Select when to propagate variable-size signals
During execution
(default) | Only when enabling
Select when to propagate variable-size signals.
During execution
Propagate variable-size signals at each time step.
Only when enabling
Propagate variable-size signals when executing a Subsystem block or Model block containing an Enable port, Trigger port with Trigger type set to
function-call
, or Action Port block. When you select this option, sample time must be periodic.
Dependencies
To display and enable this parameter for a Trigger
port block, select Function-call
from the
Trigger type list.
Programmatic Use
Block Parameter:
PropagateVarSize |
Type: character vector |
Values:
'During execution' | 'Only when
enabling' |
Default:
'During execution' |
Show output port — Control display of output port
off
(default) | on
Control display of an output port for a signal that identifies the trigger signal or function-call event signal.
Select this parameter to display the output port and determine which signal caused the trigger signal or function-call event. The width of the output port signal is the width of the control signal. The signal value is:
1
for a signal that causes a rising trigger-1
for a signal that causes a falling trigger2
for a function-call event0
in all other cases
Clear this parameter to remove the output port.
Dependencies
To display and enable this parameter, select an option other than
message
from the Trigger type list.
Programmatic Use
Block Parameter:
ShowOutputPort |
Type: character vector |
Values:
'off' | 'on' |
Default:
'off' |
Output data type — Select output port data type
auto
(default) | double
| int8
Select the output port data type for the signal that identifies the trigger signal or function-call event signal.
auto
Data type is the same as the port connected to the output.
double
Double value.
int8
Integer value
Dependencies
To enable this parameter, select the Show output port check box.
The Trigger block ignores the Data type override setting for the Fixed-Point Tool.
Programmatic Use
Block Parameter:
OutputDataType |
Type: character vector |
Values:
'auto' | 'double' |
'int8' |
Default:
'auto' |
Sample time type — Select calling rate
triggered
(default) | periodic
Select the calling rate for a subsystem or model.
triggered
Apply to applications that do not have a periodic function-call frequency. A function-call initiator can execute a triggered (aperiodic) function-call subsystem one or more times per time step and can provide a series of aperiodic function-call events.
periodic
A function-call initiator can execute a periodic function-call system only once per time step and must provide a series of periodic function-call events.. A Stateflow chart is an example of a function-call initiator.
Dependencies
To enable this parameter, select
Function-call
from the
Trigger type list.
Programmatic Use
Block Parameter:
SampleTimeType |
Type: character vector |
Values:
'triggered' |
'periodic' |
Default:
'triggered' |
Sample time — Specify time interval
-1
(default) | Ts
| [Ts, To]
Specify the time interval between function calls to a subsystem or model containing this Trigger port block. If the actual calling rate for the subsystem or model differs from the time interval this parameter specifies, Simulink® displays an error.
-1
Inherit time interval from the control signal.
Ts
Scalar where Ts is the time interval.
[Ts, To]
Vector where Ts is the time interval and To is the initial time offset.
Dependencies
To enable this parameter, select
function-call
from the Trigger type list and
periodic
from the Sample time type list.
Programmatic Use
Block Parameter:
SampleTime |
Type: character vector |
Values:
'-1' | 'Ts' |
'[Ts, To]' |
Default:
'-1' |
Enable zero-crossing detection — Control zero-crossing detection
on
(default) | off
Select this parameter to detect zero crossings.
Dependencies
To enable this parameter, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
ZeroCross |
Type: character vector |
Values:
'on' | 'off' |
Default:
'on' |
Initial trigger signal state — Select the initial state of the trigger signal
compatibility (no trigger on first
evaluation)
(default) | zero
| positive
| negative
Select the initial state of the trigger control signal.
compatibility (no trigger on first evaluation)
No trigger at the first evaluation of trigger signal. If you choose this option and the Trigger block is in a subsystem where the states are reset, the block does not reset.
zero
Zero. Helps to evaluate a rising or falling trigger signal at the first time step.
positive
Positive value. Helps to evaluate a falling trigger signal at the first time step.
negative
Negative value. Helps to evaluate a rising trigger signal at the first time step.
Dependencies
To display and activate this parameter, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
InitialTriggerSignalState |
Type: character vector |
Values:
'compatibility (no trigger on first
evaluation)' | 'zero' |
'positive' |
'negative' |
Default:
'compatibility (no trigger on first
evaluation)' |
Trigger time — Specify when message input triggers execution of subsystem
on message
available
(default) | on sample time hit
For a subsystem triggered by message input, specify timing of execution.
on message available
Trigger execution of subsystem and pull messages whenever one or more messages are available at the control port.
on sample time hit
At each time step, check whether a message is available at the control port. If so, pull one message and trigger execution of subsystem. If no message is available, do not execute subsystem at that time step.
Dependencies
To display and activate this parameter, select
message
from the Trigger
type list.
Programmatic Use
Block Parameter:
TriggerTime |
Type: character vector |
Values: 'on
message available' | 'on sample time
hit' |
Default: 'on
message available' |
Schedule as aperiodic partition — Specify immediate mode or scheduled mode for execution
on
(default) | off
For a subsystem triggered by message availability, specify execution mode.
Clear this check box for immediate mode, in which the subsystem executes as soon as a message is available at the control port, which pushes the message to the subsystem without a queue buffering the message.
Select this check box for scheduled mode, which allows subsystem execution to be deferred after a specific Simulink task while staying at the same time step.
Dependencies
To display and activate this parameter, select
message
from the Trigger
type list, then select on message
available
from the Trigger
time list.
Programmatic Use
Block Parameter:
ScheduleAsAperiodic |
Type: character vector |
Values:
'on' | 'off' |
Default:
'on' |
Signal Attributes
Port dimensions — Specify dimensions for the trigger signal
1
(default) | [n]
| [m n]
Specify dimensions for the trigger signal attached externally a Model block and passed to the inside of the block.
1
Scalar signal.
[n]
Vector signal of width
n
.[m n]
Matrix signal having
m
rows andn
columns.
Dependencies
To display and enable this parameter for a Trigger
port block at the root-level of a model, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
PortDimensions |
Type: character vector |
Values:
'1' | '[n]' |
'[m n]' |
Default:
'1' |
Trigger signal sample time — Specify time interval
-1
(default) | Ts
| [Ts, To]
Specify time interval between block method executions for the block driving the trigger signal.
-1
Inherit time interval.
Ts
Scalar where Ts is the time interval.
[Ts, To]
Vector where Ts is the time interval and To is the initial time offset.
Dependencies
To display and enable this parameter for a Trigger
port block at the root-level of a model, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
TriggerSignalSampleTime |
Type: character vector |
Values:
'-1' | 'Ts' |
'[Ts, To]' |
Default:
'-1' |
Minimum — Specify minimum output value for the trigger signal
[]
(default) | real scalar
Specify minimum value for the trigger signal attached externally to a Model block and passed to the inside of the block.
Simulink uses this value to perform:
Simulation range checking. See Specify Signal Ranges.
Automatic scaling of fixed-point data types.
Optimization of generated code. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. See Optimize using the specified minimum and maximum values (Embedded Coder).
[]
Unspecified minimum value.
- real scalar
Real scalar value.
Dependencies
To display and enable this parameter for a Trigger
port block at the root-level of a model, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
OutMin |
Type: character vector |
Values:
'[]' | '<real
scalar>' |
Default:
'[]' |
Maximum — Specify maximum output value for the trigger signal
[]
(default) | real scalar
Specify maximum value for the trigger signal attached externally to a Model block and passed to the inside of the block.
Simulink uses this value to perform:
Simulation range checking. See Specify Signal Ranges.
Automatic scaling of fixed-point data types.
Optimization of generated code. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. See Optimize using the specified minimum and maximum values (Embedded Coder).
[]
Unspecified maximum value.
- real scalar
Real scalar value.
Dependencies
To display and enable this parameter for a Trigger
port block at the root-level of a model, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
OutMax |
Type: character vector |
Values:
'[]' | '<real
scalar>' |
Default:
'[]' |
Data type — Select output data type for the trigger signal
double
(default) | single
| int8
| uint8
| int16
| uint16
| int32
| uint32
| int64
| uint64
| boolean
| fixdt(1,16)
| fixdt(1,16,0)
| fixdt(1,16,2^,0)
| <data type expression>
Select data type for the trigger signal attached externally to a Model block and passed to the inside of the block.
double
Double-precision floating point.
single
Single-precision floating point.
int8
Signed 8-bit integer.
uint8
Unsigned 8-bit integer.
int16
Signed 16-bit integer.
uint16
Unsigned 16-bit integer.
int32
Signed 32-bit integer.
uint32
Unsigned 32-bit integer.
int64
Signed 64-bit integer.
uint64
Unsigned 64-bit integer.
boolean
Boolean with a value of
true
orfalse
.fixdt(1,16)
Signed 16-bit fixed point number with binary point undefined.
fixdt(1,16,0)
Signed 16-bit fixed point number with binary point set to zero.
fixdt(1,16,2^,0)
Signed 16-bit fixed point number with slope set to
2^0
and bias set to0
.<data type expression>
Data type object, for example
Simulink.NumericType
. You cannot enter the name of aSimulink.Bus
object as a data type expression.
Dependencies
To display and enable this parameter for a Trigger
port block at the root-level of a model, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
OutDataTypeStr |
Type: character vector |
Values:
'double' | 'single' |
'int8' | 'uint8' |
'int16' | 'uint16' |
'int32' | 'uint32' |
'int64' | 'uint64' |
'boolean' |
'fixdt(1,16)' |
'fixdt(1,16,0)' |
'fixdt(1,16,2^0,0)' | '<data
type expression>' |
Default:
'double' |
Mode — Select data type category
Built in
(default) | Fixed point
| Expression
Select data type category and display drop-down lists to help you define the data type.
Built in
Display drop-down lists for data type and Data type override.
Fixed point
Display drop-down lists for Signedness, Scaling, and Data type override.
Expression
Display text box for entering an expression.
Dependencies
To enable this parameter, select the Show data type assistant
button .
Programmatic Use
No equivalent command-line parameter.
Interpolate data — Control how missing workspace data is estimated
on (default) | off
Control how missing workspace data is estimated when loading data from the MATLAB® workspace.
Select this parameter to linearly interpolate output at time steps for which no corresponding workspace data exists.
Clear this parameter to set the output at such time steps equal to the output at the most recent time step for which data exists.
Dependencies
To display and enable this parameter for a Trigger
port block at the root-level of a model, select
rising
,
falling
, or
either
from the Trigger
type list.
Programmatic Use
Block Parameter:
Interpolate |
Type: character vector |
Values:
'on' | 'off' |
Default:
'on' |
Block Characteristics
Data Types |
|
Direct Feedthrough |
|
Multidimensional Signals |
|
Variable-Size Signals |
|
Zero-Crossing Detection |
|
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.
HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic. See also HDL Code Generation.
This block has one default HDL architecture.
You cannot generate HDL code for a Trigger Block that has Trigger
type set to function-call
or
message
.
PLC Code Generation
Generate Structured Text code using Simulink® PLC Coder™.
Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.
Version History
Introduced before R2006a
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