Simulink生成C代码时为何创建MEX文件？能否规避该过程？

Great question—this is a common source of confusion when working with Simulink’s code generation pipeline. Let’s break this down into two parts: why those MEX files are appearing, and how to skip creating them if you don’t need them.

Why MEX Files Are Generated (Even for Normal-Mode References) #

Simulink uses MEX files here for pre-code-generation validation and consistency checks, not just for accelerator mode simulations. Here’s the key reasoning:

• Early Error Detection: Before committing to full C code generation, Simulink needs to confirm referenced models behave as expected and their interfaces (inputs/outputs, parameters) play nicely with the main model. A temporary MEX file lets it run a quick lightweight simulation to catch issues early, avoiding wasted time on a full code build for an invalid setup.
• Default Configuration Biases: Many out-of-the-box code generation settings (like the ModelReferenceBuildConfiguration parameter) prioritize validation. Even with normal-mode references, Simulink defaults to building MEX files to ensure referenced models are code-generable and free of quirks that would break the C code build.
• Custom Logic Validation: If your referenced models include MATLAB Function blocks, Stateflow charts, or custom C code, Simulink often compiles MEX files to verify these components can be translated into C correctly. It’s a pre-flight check to avoid unexpected failures during the final code generation step.

How to Skip MEX File Creation During C Code Generation #

If you’re confident in your model’s validity and want to skip MEX file generation, adjust your configuration with one of these methods:

1. Using the Simulink GUI #

• Open your main model’s Configuration Parameters (press Ctrl+E).
• Navigate to Code Generation > Model Referencing.
• Set Build configuration for referenced models to None or Generate code only (label may vary slightly by Simulink version). This tells Simulink to skip validation MEX builds and focus solely on C code generation.
• Additionally, go to Simulation > Simulation Target and set Accelerator mode to Off to eliminate any leftover accelerator-related build triggers.

2. Using MATLAB Command Line #

For script-based control, use set_param to tweak the relevant parameters:

# Configure main model to skip MEX builds for references
set_param('your_main_model_name', 'ModelReferenceBuildConfiguration', 'None');
set_param('your_main_model_name', 'SimulationMode', 'Normal');

# Optional: Configure individual referenced models to avoid MEX builds
set_param('your_referenced_model_name', 'BuildConfiguration', 'None');

Edge Cases to Note #

If your referenced models include MATLAB Function blocks or Stateflow charts, Simulink may still generate minimal MEX files to validate these components. To reduce this:

• For MATLAB Function blocks: Open the block’s configuration, go to Build Options, and set Build action to Code Generation Only. This skips simulation-focused MEX builds and only prepares code for C generation.

内容的提问来源于stack exchange，提问作者JohnND