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Detect Change

Detect change in signal value

  • Detect Change block

Libraries:
Simulink / Logic and Bit Operations
HDL Coder / Logic and Bit Operations

Description

The Detect Change block determines if an input signal does not equal its previous value. The initial condition determines the initial value of the previous input U/z.

This block supports only discrete sample times.

Examples

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This example shows how to detect a change in signal values using the Detect Change block. When the input from the Pulse Generator block remains the same, the Detect Change block outputs zero (false), indicating that there was no change in signal values. When the value of the Pulse Generator block changes, the Detect Change block outputs one (true) indicating that the current signal value does not equal its previous value.

Ports

Input

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Input signal, specified as a scalar, vector, or matrix.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | built-in integer | floating point

Output

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Output signal, true (equal to 1) when the input signal does not equal its previous value; false (equal to 0) when the input signal equals its previous value.

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

Parameters

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Set the initial condition for the previous input U/z.

Programmatic Use

Block Parameter: vinit
Type: character vector
Values: scalar | vector
Default:'0'

Specify whether the block performs sample- or frame-based processing:

  • Columns as channels (frame based) — Treat each column of the input as a separate channel (frame-based processing).

    Note

    Frame-based processing requires a DSP System Toolbox™ license.

    For more information, see Sample- and Frame-Based Concepts (DSP System Toolbox).

  • Elements as channels (sample based) — Treat each element of the input as a separate channel (sample-based processing).

Use Input processing to specify whether the block performs sample- or frame-based processing. For more information about these two processing modes, see Sample- and Frame-Based Concepts (DSP System Toolbox).

Programmatic Use

Block Parameter: InputProcessing
Type: character vector
Values: 'Columns as channels (frame based)' | 'Elements as channels (sample based)'
Default: 'Elements as channels (sample based)'

Set the output data type to boolean or uint8.

Programmatic Use

Block Parameter: OutDataTypeStr
Type: character vector
Values: 'boolean' | 'uint8'
Default: 'boolean'

Block Characteristics

Data Types

Boolean | double | enumerated | fixed point | integer | single

Direct Feedthrough

yes

Multidimensional Signals

yes

Variable-Size Signals

yes

Zero-Crossing Detection

no

Extended Capabilities

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