You can perform
a behavioral simulation on your design before synthesis with the Simulate
Behavioral Model process. This first pass simulation is typically
performed to verify RTL (behavioral) code and to confirm that the
design is functioning as intended. Behavioral simulation can be performed
on a source file available in the Behavioral Simulation Design View,
which may include any of the following:
- HDL test benches
- HDL source files used for both synthesis and behavioral simulation
- Simulation-only HDL source files, such as IP simulation models
or external simulation models
Note This process is recommended prior to synthesizing your
design.
To Perform Behavioral Simulation
- Compile the HDL simulation libraries (VHDL/Verilog UNISIM, SIMPRIM, XilinxCoreLib, SmartModels).

Note This step is not necessary when using ModelSim Xilinx® Edition
(MXE) or ISim, because the libraries are already pre-compiled
for those simulators. If using MXE, ensure that you have the latest
libraries downloaded and installed from the Xilinx Download Center.
Go to Help > Xilinx on the Web > Download Center to find the latest MXE libraries.
- In the Design panel, select Behavioral Simulation from the Design View drop-down list.

- In the Hierarchy pane, select a test bench file or an HDL
source file to simulate.
- In the Processes pane, expand ISim Simulator or ModelSim Simulator.
- Right-click Simulate Behavioral Model, and select Process Properties.
- In the Process Properties dialog box, set the following
properties:
- Double-click Simulate Behavioral Model.
A simulation execution script is created and invoked by
the simulator. The files that are passed to the simulation include
the following:
- Test bench file.
- Design VHDL or Verilog file or any associated core files for
simulation.
Simulation is performed and the results
are displayed in your simulator. If no stimulus is available, the
design is simply compiled and loaded in the simulator. You must then
create a stimulus file and perform a simulation on the design in the
simulator.
Note For more information
about using ModelSim, see the ModelSim Simulator documentation.
For more information about using ISim, see the
ISim Help.
In the Help Viewer, click the Synchronize TOC
button
to view all
related Help topics. After running this process, you can perform any of the
following:
- Analyze the results of the simulation process in your simulator.
- Repeat the behavioral simulation, if necessary.
- Run the Synthesize process.

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