PS Step

R2026b

Generate physical signal shaped as step function

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PS Step block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simscape / Foundation Library / Physical Signals / Sources

Description

The PS Step block generates a physical signal that starts at a specified initial value and changes instantaneously to a new value at a specified time. The Step time, Initial value, and Final value parameters determine the characteristics of the output signal:

• The Step time parameter determines when the signal value changes from Initial value to Final value.

• The Initial value and Final value parameter values determine whether the output signal is a scalar, vector, or matrix. If one of these parameters is a vector or a matrix, the other must be a vector or a matrix of the same size or a scalar. The output signal is then also a vector or a matrix of the same size.

• The Initial value and Final value parameters must have commensurate units. The unit at the output port is determined by unit propagation rules. If the two parameters have the same units, then the output signal unit is also the same. If the parameter units are different, then the unit of the output signal is the base unit commensurate with the units of the parameters. For more information, see Physical Signal Unit Propagation.

Ports

Output

O — Output physical signal, typed by the block parameter values and units

physical signal

Output physical signal. The signal size matches the size of Initial value and Final value parameter values. The signal unit is determined by the Initial value and Final value parameter units.

The port name is not visible in the block icon, but you can see this name in the underlying source file by clicking the Source code link in the Description tab of the block dialog box.

Programmatic Use

Port: O

Parameters

Step time — Time when step occurs

1 s (default) | scalar

Time when the signal changes value. Between the start of simulation and Step time, the output of the block remains at Initial value, then instantaneously changes to Final value and remains at that value until the end of simulation.

Programmatic Use

Parameter: step_time

Initial value — Output before step

0 1 (default) | scalar | vector | matrix

Block output until the simulation time reaches Step time. The first edit box represents the parameter value. You can specify a scalar, vector, or matrix. By default, the value is a scalar, 0. If you specify a vector or a matrix, Final value must also be a vector or a matrix of the same size or a scalar.

The second combo box represents the parameter unit. The specified unit must be commensurate with the unit of the Final value parameter. By default, the unit is 1 (unitless). You can select a unit from the drop-down list or type the desired unit name, such as Pa, or a valid expression, such as m^2. For more information and a list of unit abbreviations, see How to Specify Units in Block Dialogs and Unit Definitions.

Programmatic Use

Parameter: initial_value

Final value — Output after step

1 1 (default) | scalar | vector | matrix

Block output when the simulation time reaches and exceeds Step time. The first edit box represents the parameter value. You can specify a scalar, vector, or matrix. By default, the value is a scalar, 1. If you specify a vector or a matrix, Initial value must also be a vector or a matrix of the same size or a scalar.

The second combo box represents the parameter unit. The specified unit must be commensurate with the unit of the Initial value parameter. By default, the unit is 1 (unitless). You can select a unit from the drop-down list or type the desired unit name, such as Pa, or a valid expression, such as m^2. For more information and a list of unit abbreviations, see How to Specify Units in Block Dialogs and Unit Definitions.

Programmatic Use

Parameter: final_value

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"fl_lib/Physical Signals/Sources/PS Step"

Example: add_block("fl_lib/Physical Signals/Sources/PS Step","myModel/myBlock",MakeNameUnique="on")

For information about programmatic access to individual block parameters, see the Programmatic Use section of parameter descriptions on this page.

Extended Capabilities

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

Version History

Introduced in R2021a

R2026a: Dynamic block icon

Starting in R2026a, the block icon flips if the Initial value is greater than the Final value.