PS Constant

R2026b

Generate constant physical signal

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PS Constant 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 Constant block generates a physical signal of a constant value. You specify the value and unit of the signal as the Constant parameter.

Examples

Nonlinear Inductor

An implementation of a nonlinear inductor where inductance depends on current. A tanh function defines the nonlinear flux-current relationship. The flux saturates for large currents, which can occur, for example, in iron core inductors.

• Open Model

Two-Phase Fluid Refrigeration

Models a vapor-compression refrigeration cycle using two-phase fluid components. The compressor drives the R-134a refrigerant through a condenser, an expansion valve, and an evaporator. The hot gas leaving the compressor condenses in the condenser via heat transfer to the environment. The pressure drops as the refrigerant passes through the expansion valve. The drop in pressure lowers the saturation temperature of the refrigerant. This enables it to boil in the evaporator as it absorbs heat from the refrigerator compartment. The refrigerant then returns to the compressor to repeat the cycle. The controller turns the compressor on and off to maintain the refrigerator compartment temperature within a band around the desired temperature.

• Open Model

Ports

Output

O — Output physical signal, typed by the block parameter value

physical signal

Output physical signal. The signal value and unit are determined by the value and unit of the Constant parameter.

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

Constant — Signal value and unit

1 1 (default)

The value and unit of the output signal at port O. The first edit box represents the signal value. You can specify both positive and negative values.

The second combo box represents the unit of the output signal. 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 rpm, or a valid expression, such as rad/s. For more information and a list of unit abbreviations, see How to Specify Units in Block Dialogs and Unit Definitions.

Programmatic Use

Parameter: constant

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 Constant"

Example: add_block("fl_lib/Physical Signals/Sources/PS Constant","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 R2007b

R2026a: Dynamic block icon

Starting in R2026a, the block icon displays the Constant parameter value.

R2019a: Unit Propagation

Prior to R2019a, this block did not propagate physical units.

If your model contains legacy blocks without unit propagation, use the Upgrade Advisor to upgrade your blocks to the latest version. For more information, see Upgrading Models with Legacy Physical Signal Blocks.