Main Content

Choosing a Simulation Mode

Simulation Mode Tradeoffs

In general, you must trade off simulation speed against flexibility when choosing either accelerator mode or rapid accelerator mode instead of normal mode.

Normal mode offers the greatest flexibility for making model adjustments and displaying results, but it runs the slowest.

Accelerator mode lies between normal and rapid accelerator modes in performance and in interaction with your model. Accelerator mode does not support most runtime diagnostics.

Rapid accelerator mode runs the fastest, but this mode does not support the debugging utilities or the Simulink® Profiler, and works only with those models for which C code or MEX file is available for all of the blocks in the model.


An exception to this rule occurs when you run multiple simulations, each of which executes in less than one second in normal mode. For example:

for i=1:100
sim(model); % executes in less than one second in Normal mode
For this set of conditions, you will typically obtain the best performance by simulating the model in normal mode.


To gain additional flexibility, consider using model referencing to componentize your model. If the top model uses normal mode, then you can simulate a referenced model in a different simulation mode than you use for other portions of a model. During the model development process, you can choose different simulation modes for different portions of a model. For details, see Choose Simulation Modes for Model Hierarchies.

Comparing Modes

The following table compares the characteristics of normal mode, accelerator mode, and rapid accelerator mode.

If you want to...Then use this mode...
NormalAcceleratorRapid Accelerator
Run your model in a separate address space  
Efficiently run batch and Monte Carlo simulations  
Model Adjustment
Change model parameters such as solver, stop time without rebuilding
Change block tunable parameters such as gain
For more information on configuration set parameters which can be modified without requiring rebuild, see Code Regeneration in Accelerated Models
Model Requirement
Accelerate your model even if C code or MEX file are not used for all blocks  
Support Interpreted MATLAB Function blocks 
Support Non-Inlined MATLAB language or Fortran S-Functions 
Permit algebraic loops in your models 
Use debugging options or the Simulink Profiler 
Have your model include C++ code 
Data Display
Use scopes and signal viewersSee Behavior of Scopes and Viewers with Rapid Accelerator Mode
Use scopes and signal viewers when simulating your model programmatically 


Scopes and viewers do not update if you run your model programmatically in rapid accelerator mode.

Decision Tree

Use this decision tree to select between accelerator mode and rapid accelerator mode.

See Comparing Performance to understand how effective acceleration will be in improving the performance of your model.

Related Topics