Check Static Lower Bound

Check that signal is greater than (or optionally equal to) static lower bound

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Libraries:
Simulink / Model Verification
HDL Coder / Model Verification

Description

The Check Static Lower Bound block checks if an input signal is greater than (or optionally equal to) a specified lower bound at each time step and executes an assertion after comparison. The Lower bound parameter defines the lower bound. If the input signal is greater than the lower bound, the assertion is true (1) and the block does nothing. If not, the block halts the simulation and returns an error message by default.

The input signal and bound can be scalars, vectors, or matrices. The input and the bound must be the same data type. The block compares the value of the input to the bound differently depending on the signal.

• When comparing scalars to vectors or matrices, the block compares the scalar to each element of the non-scalar input signal or bound.

• When comparing a vector or matrix input signal to a vector or matrix bound, the block compares the input signal to the bound element-by-element.

• For models with an input signal and bound that are both vectors or matrices, the input signal and bound must have the same dimensions.

Examples

Check Signal Lower Bound with Check Static Lower Bound Block

Using the Check Static Lower Bound block, you can check if an input signal falls below a defined value.

In this example, the Check Static Lower Bound block compares the value of a Sine Wave block to the value entered in the Lower bound parameter, which is 0.5. The Constant block, labeled Bound, illustrates this parameter in the Scope block but does not affect the parameter value. The Check Static Lower Bound block checks if the value of the input signal is greater than the Lower bound. If it is, the block asserts true (1). Because the Output assertion signal parameter of the block is selected, the block outputs the assertion value. Run the simulation to observe the model output.

At the start of the simulation, the Check Static Lower Bound block outputs 0 because the value of the Sine Wave block is less than the bound. At a time of 0.52, the sine wave exceeds 0.5. The Check Static Lower Bound block recognizes this change and outputs 1. When the time reaches 2.62, the sine wave falls below the bound and the assertion is false. This pattern repeats until the simulation end time.

Ports

Input

Port_1 — Input signal checked against bound

scalar | vector | matrix

Input signal checked against the lower bound specified by the Lower bound parameter.

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

Output

Port_1 — Assertion output signal

scalar

Output signal that is true (1) if the assertion succeeds and false (0) if the assertion fails. If, in the Configuration Parameters window, in the Math and Data Types section, under Advanced parameters, you select Implement logic signals as Boolean data, then the output data type is Boolean. Otherwise, the data type of the signal is double.

Dependencies

To enable this output port, select the Output assertion signal parameter check box.

Data Types: double | Boolean

Parameters

Lower bound — Lower boundary value

scalar | vector | matrix

Specify the lower bound on the range of amplitudes that the input signal can have.

Programmatic Use

Parameter: min

Type: string scalar or character vector

Default: "0"

Inclusive boundary — Include the lower bound in range

on (default) | off

Select this check box to make the range of valid input amplitudes include the lower bound.

Programmatic Use

Parameter: min_included

Type: string scalar character vector

Values: "on" | "off"

Default: "on"

Enable assertion — Enable or disable check

on (default) | off

Clearing this parameter disables the block and causes the model to behave as if the block does not exist. To enable or disable all verification blocks, regardless of the setting of this option, go to the Configuration Parameters window, click Diagnostics > Data Validity, expand the Advanced parameters section, and set Model Verification block enabling to Enable all or Disable all.

Programmatic Use

Parameter: enabled

Type: string scalar or character vector

Values: "on" | "off"

Default: "on"

Simulation callback when assertion fails (optional) — Expression to evaluate when assertion fails

"" (default) | MATLAB expression

Specify a MATLAB^® expression to evaluate when the assertion fails. Because the expression is evaluated in the MATLAB workspace, define all variables used in the expression in that workspace.

Dependencies

To enable this parameter, select Enable assertion.

Programmatic Use

Parameter: callback

Type: string scalar or character vector

Default: ""

Stop simulation when assertion fails — Whether to stop simulation when check fails

on (default) | off

Select this parameter to stop the simulation when the check fails. Clear this parameter to display a warning and continue the simulation.

Programmatic Use

Parameter: stopWhenAssertionFail

Type: string scalar or character vector

Values: "on" | "off"

Default: "on"

Output assertion signal — Create output signal

off (default) | on

Select this parameter to enable the output port.

Programmatic Use

Parameter: export

Type: string scalar or character vector

Values: "on" | "off"

Default: "off"

Select icon type — Select icon type

graphic (default) | text

Specify the style of the block icon. The graphic option displays a graphical representation of the assertion condition on the icon. The text option displays a mathematical expression that represents the assertion condition.

Programmatic Use

Parameter: icon

Type: string scalar or character vector

Values: "graphic" | "text"

Default: "graphic"

Block Characteristics

Data Types	Boolean | double | enumerated | fixed point | half | 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™.

For information about how Simulink^® Coder™ generated code handles Model Verification blocks, see Configure Model for Debugging (Simulink Coder).

Not recommended for production code.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

Architecture	Description
No HDL	Do not generate HDL code for this block.

HDL Block Properties

PreserveUpstreamLogic

Control the removal of unconnected logic. The default is off, which means unconnected logic is not preserved in HDL code. For more details, see PreserveUpstreamLogic (HDL Coder).

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