Simulink Reference

Switch

Switch output between the first input and the third input based on the value of the second input

Library

Simulink Signal Routing and Fixed-Point Blockset Select

Description

The Switch block passes through the first (top) input or the third (bottom) input based on the value of the second (middle) input. The first and third inputs are called data inputs. The second input is called the control input.

You select the conditions under which the first input is passed with the Criteria for passing first input parameter. You can make the block check whether the control input is greater than or equal to the threshold value, purely greater than the threshold value, or nonzero. If the control input meets the condition set in the Criteria for passing first input parameter, then the first input is passed. Otherwise, the third input is passed.

When the Show additional parameters check box is selected, some of the parameters that become visible are common to many blocks. For a detailed description of these parameters, refer to Block Parameters in the Fixed-Point Blockset documentation.

Data Type Support

The data and control inputs of a Switch block accept real or complex signals of any data type supported by Simulink, as well as fixed-point data types.

For a discussion on the data types supported by Simulink, refer to Data Types Supported by Simulink in the Using Simulink documentation.

Parameters and Dialog Box

Criteria for passing first input

Select the conditions under which the first input is passed. You can make the block check whether the control input is greater than or equal to the threshold value, purely greater than the threshold value, or nonzero. If the control input meets the condition set in this parameter, then the first input is passed. Otherwise, the third input is passed.

Threshold

Assign the switch threshold that determines which input is passed to the output.

Show additional parameters

If selected, additional parameters specific to implementation of the block become visible as shown.

Require all data port inputs to have same data type

Select to require all data inputs to have the same data type.

Output data type mode

Choose to inherit the output data type and scaling by backpropagation or by an internal rule. The internal rule causes the output of the block to have the same data type and scaling as the input with the larger positive range.

Round integer calculations toward

Select the rounding mode for fixed-point output.

Saturate on integer overflow

If selected, overflows saturate.

Enable zero crossing detection

Select to enable zero crossing detection. For more information, see Zero Crossing Detection in the Using Simulink documentation.

Characteristics

Dimensionalized	Yes
Direct Feedthrough	Yes
Sample Time	Inherited from driving block
Scalar Expansion	Yes
Zero Crossing	No, unless Enable zero crossing detection is selected

See Also

Multi-Port Switch

Sum

Switch Case