Relay
Switch output between two constants
- Library:
Simulink / Discontinuities
HDL Coder / Discontinuities
Description
The output for the Relay block switches 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.
Note
When the initial input falls between the Switch off point and Switch on point values, the initial output is the value when the relay is off.
Ports
Input
Output
Parameters
Switch on point — Input value which switches the relay on
'eps' (default) | scalar
When the input crosses this threshold, the relay switches on. 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 models hysteresis, whereas specifying equal values models a switch with a threshold at that value.
The Switch on point parameter is converted to the input data type offline using round-to-nearest and saturation methods.
Programmatic Use
Block Parameter:
OnSwitchValue |
| Type: character vector |
| Values: scalar |
Default:
'eps' |
Switch off point — Input value which switches the relay off
'eps' (default) | scalar
When the input crosses this threshold the relay switches off. The value of Switch off point must be less than or equal to Switch on point. The Switch off point parameter is converted to the input data type offline using round-to-nearest and saturation.
Programmatic Use
Block Parameter:
OffSwitchValue |
| Type: character vector |
| Values: scalar |
Default:
'eps' |
Output when on — Output value when the relay is on
1 (default) | scalar
The output value when the relay is on.
Programmatic Use
Block Parameter:
OnOutputValue |
| Type: character vector |
| Values: scalar |
Default:
'1' |
Output when off — Output value when the relay is off
0 (default) | scalar
The output value when the relay is off.
Programmatic Use
Block Parameter:
OffOutputValue |
| Type: character vector |
| Values: scalar |
Default:
'0' |
Input processing — Specify sample- or frame-based processing
Elements as channels (sample based) (default) | Columns as channels (frame based)
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. The block accepts frame-based signals for the input
u. All other input signals must be sample-based.
| Input Signal u | Input Processing Mode | Block Works? |
|---|---|---|
| Sample based | Sample based | Yes |
| Frame based | No, produces an error | |
| Sample based | Frame based | Yes |
| Frame based | Yes |
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)' |
Enable zero-crossing detection — Enable zero-crossing detection
on (default) | Boolean
Select to enable zero-crossing detection. For more information, see Zero-Crossing Detection.
Programmatic Use
Block Parameter:
ZeroCross |
| Type: character vector, string |
Values: 'off' |
'on' |
Default: 'on' |
Sample time — Specify sample time as a value other than -1
-1 (default) | scalar | vector
Specify the sample time as a value other than -1. For more information, see Specify Sample Time.
Dependencies
This parameter is not visible unless it is explicitly set to a value other than
-1. To learn more, see Blocks for Which Sample Time Is Not Recommended.
Programmatic Use
Block Parameter:
SampleTime |
| Type: character vector |
| Values: scalar or vector |
Default:
'-1' |
Output minimum — Minimum output value for range checking
[] (default) | scalar
Lower value of the output range that Simulink® checks.
Simulink uses the minimum to perform:
Parameter range checking (see Specify Minimum and Maximum Values for Block Parameters) for some blocks.
Simulation range checking (see Specify Signal Ranges and Enable Simulation Range Checking).
Automatic scaling of fixed-point data types.
Optimization of the code that you generate from the model. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. For more information, see Optimize using the specified minimum and maximum values (Embedded Coder).
Note
Output minimum does not saturate or clip the actual output signal. Use the Saturation block instead.
Programmatic Use
Block Parameter:
OutMin |
| Type: character vector |
Values: '[ ]'|
scalar |
Default: '[ ]' |
Output maximum — Maximum output value for range checking
[] (default) | scalar
Upper value of the output range that Simulink checks.
Simulink uses the maximum value to perform:
Parameter range checking (see Specify Minimum and Maximum Values for Block Parameters) for some blocks.
Simulation range checking (see Specify Signal Ranges and Enable Simulation Range Checking).
Automatic scaling of fixed-point data types.
Optimization of the code that you generate from the model. This optimization can remove algorithmic code and affect the results of some simulation modes such as SIL or external mode. For more information, see Optimize using the specified minimum and maximum values (Embedded Coder).
Note
Output maximum does not saturate or clip the actual output signal. Use the Saturation block instead.
Programmatic Use
Block Parameter:
OutMax |
| Type: character vector |
Values: '[ ]'|
scalar |
Default: '[ ]' |
Output data type — Data type of output signal
Inherit: All ports same
datatype (default) | Inherit: Inherit via back propagation | double | single | int8 | int32 | uint32 | int64 | uint64 | fixdt(1,16,2^0,0) | <data type expression> | ...
Specify the output data type. You can set it to:
A rule that inherits a data type, for example,
Inherit: Inherit via back propagationThe name of a built-in data type, for example,
singleThe name of a data type object, for example, a
Simulink.NumericTypeobjectAn expression that evaluates to a data type, for example,
fixdt(1,16,0)
Click the Show data type assistant button
to display the Data Type
Assistant, which helps you set the Output data
type parameter.
See Control Signal Data Types for more information.
Programmatic Use
Block Parameter:
OutDataTypeStr |
| Type: character vector |
Values: 'Inherit: Same as input',
'Inherit: Inherit via back propagation',
'single', 'int8',
'uint8', int16,
'uint16', 'int32',
'uint32', 'int64',
'uint64', fixdt(1,16,0),
fixdt(1,16,2^0,0),
fixdt(1,16,2^0,0). '<data type
expression>' |
Default: 'Inherit:
Same as input' |
Lock data type settings against changes by the fixed-point tools — Prevent fixed-point tools from overriding data types
off (default) | on
Select this parameter to prevent the fixed-point tools from overriding the data types you specify on this block. For more information, see Lock the Output Data Type Setting (Fixed-Point Designer).
Programmatic Use
Block Parameter: LockScale |
| Type: character vector |
Values: 'off' | 'on' |
Default: 'off' |
Model Examples
Block Characteristics
Data Types |
|
Direct Feedthrough |
|
Multidimensional Signals |
|
Variable-Size Signals |
|
Zero-Crossing Detection |
|