About Blocks :: Working with Blocks (Simulink®)

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About Blocks

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What Are Blocks? Block Data Tips Virtual Blocks

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What Are Blocks?

Blocks are the elements from which the Simulink software builds models. You can model virtually any dynamic system by creating and interconnecting blocks in appropriate ways. This section discusses how to use blocks to build models of dynamic systems.

Block Data Tips

Information about a block is displayed in a pop-up window when you allow the pointer to hover over the block in the diagram view. To disable this feature or control what information a data tip includes, select Block data tips options from the Simulink View menu.

Virtual Blocks

When creating models, you need to be aware that Simulink blocks fall into two basic categories: nonvirtual blocks and virtual blocks. Nonvirtual blocks play an active role in the simulation of a system. If you add or remove a nonvirtual block, you change the model's behavior. Virtual blocks, by contrast, play no active role in the simulation; they help organize a model graphically. Some Simulink blocks are virtual in some circumstances and nonvirtual in others. Such blocks are called conditionally virtual blocks. The following table lists Simulink virtual and conditionally virtual blocks.

Block Name	Condition Under Which Block Is Virtual
Bus Assignment	Virtual if input bus is virtual.
Bus Creator	Virtual if output bus is virtual.
Bus Selector	Virtual if input bus is virtual.
Demux	Always virtual.
Enable	Virtual unless connected directly to an Outport block.
From	Always virtual.
Goto	Always virtual.
Goto Tag Visibility	Always virtual.
Ground	Always virtual.
Inport	Virtual unless the block resides in a conditionally executed or atomic subsystem and has a direct connection to an Outport block.
Mux	Always virtual.
Outport	Virtual when the block resides within any subsystem block (conditional or not), and does not reside in the root (top-level) Simulink window.
Selector	Virtual only when Number of input dimensions specifies `1` and Index Option specifies `Select all`, `Index vector (dialog)`, or `Starting index (dialog)`.
Signal Specification	Always virtual.
Subsystem	Virtual unless the block is conditionally executed or the Treat as atomic unit check box is selected. You can check if a block is virtual with the `IsSubsystemVirtual` block property. See Block-Specific Parameters in the Simulink Reference.
Terminator	Always virtual.
Trigger	Virtual when the output port is not present.

Working with Blocks

Adding Blocks

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