Ground
Ground unconnected input port
Libraries:
Simulink /
Commonly Used Blocks
Simulink /
Sources
HDL Coder /
Sources
Description
The Ground block connects to blocks whose input ports do not connect to other blocks. If you run a simulation with blocks that have unconnected input ports, the software issues warnings. Using a Ground block to ground those unconnected blocks can prevent these warnings.
Working with Fixed-Point Data Types
When working with fixed-point data types, there may be instances where the fixed-point data type cannot represent zero exactly. In these cases, the Ground block outputs a nonzero value that is the closest possible value to zero. This behavior applies only to fixed-point data types with nonzero bias. These expressions are examples of fixed-point data types that cannot represent zero:
fixdt(0, 8, 1, 1)— an unsigned 8-bit type with slope of 1 and bias of 1fixdt(1, 8, 6, 3)— a signed 8-bit type with slope of 6 and bias of 3
Working with Enumerated Data Types
When working with enumerated data types, the Ground block outputs the default value of the enumeration. This behavior applies whether:
The enumeration can represent zero
The default value of the enumeration is zero
If the enumerated type does not have a default value, the Ground block outputs the first enumeration value in the type definition.
Examples
This example shows how to use the Ground block to ground block input ports that have integer and enumerated data types. In top row of this example, the output of the Constant block determines the data type (int8) of the port to which the Ground block is connected. That port determines the output data type of the Ground block, and the Ground block outputs a signal with zero value, and data type int8.
In the bottom row of this example, the Ground block is connected to a port with an enumerated data type. For enumerated data types, the Ground block outputs the default value of the enumeration. This behavior applies whether or not:
The enumeration can represent zero
The default value of the enumeration is zero
If the enumerated type does not have a default value, the Ground block outputs the first enumeration value in the type definition.
This example shows how to use the Ground block to ground block input ports that have fixed-point data types. The top row of this example illustrates the Ground block behavior when the fixed-point data type can represent zero. In that case, the Ground block outputs a signal with zero value, and the same fixed-point data type as the port it is connected to.
In the bottom row of this example, the output of the Constant block determines the data type of the port to which the Ground block is connected (fixdt(0,8,1,1)). Because zero cannot be represented exactly by the data type fixdt(0,8,1,1), the Ground block outputs a nonzero value that is the closest possible value to zero (in this case, 1).
Extended Examples
Double Bouncing Ball: Use of Adaptive Zero-Crossing Location
Choose the correct zero-crossing location algorithm, based on the system dynamics. For Zeno dynamic systems, or systems with strong chattering, you can select the adaptive zero-crossing detection algorithm through the Configure pane:
Triggered Subsystems
Model showing triggered subsystems and different types of triggers.
Ports
Output
Block Characteristics
Data Types |
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Direct Feedthrough |
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Multidimensional Signals |
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Variable-Size Signals |
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Zero-Crossing Detection |
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Extended Capabilities
Version History
Introduced before R2006a
