Switch output between two constants.

Description

The FixPt Relay block is a masked S-function that allows the output to switch between two specified values. When the relay is on, it remains on until the input drops below the value of the Switch off point parameter. When the relay is off, it remains off until the input exceeds the value of the Switch on point parameter. The block accepts one input and generates one output.

The Switch on point value must be greater than or equal to the Switch off point. Specifying a Switch on point value greater than the Switch off point value models hysteresis, whereas specifying equal values models a switch with a threshold at that value.

You specify the output scaling with the Output scaling parameter. Note that there are two dialog box parameters that control the output scaling: one associated with an edit field, and one associated with a parameter list. If Output data type is a generalized fixed-point number such as sfix(16), the Output scaling parameter list provides you with these scaling modes:

• Use Specified Scaling - This mode uses the slope/bias or radix point-only scaling specified for the editable Output scaling parameter (for example, 2^-10).

• Best Precision: Vector-wise - This mode produces the best precision based on the Output when on and Output when off parameters.

For a detailed description of all other block parameters, refer to Block Parameters.

Parameters and Dialog Box

Open

• Switch on point - The "on" threshold for the relay. 

• Switch off point - The "off" threshold for the relay.

• Output when on - The output when the relay is on.

• Output when off - The output when the relay is off.

• Output data type and scaling - Specify the output data type and scaling via the dialog box, or inherit the data type and scaling by back propagation.

• Output data type - Any data type supported by the Fixed-Point Blockset.

• Output scaling - Radix point-only or slope/bias scaling. Additionally, you can scale the Output when on and Output when off parameters using the constant vector scaling mode for maximizing precision.These scaling modes are available only for generalized fixed-point data types.

• Override with doubles - If checked, the Output data type is overridden with doubles.

Conversions

Both the Switch on point and Switch off point parameters are converted to the input data type offline using round-to-nearest and saturation.

Characteristics