Hi Lorenz,
I understand that you have a requirement to log signal data into the SD card mounted on your target hardware. Considering your setup, I suggest using Embedded Coder Support Package for STMicroelectronics STM32 Processors. You can use various output blocks in Simulink like To Workspace, Scope, and Outport to save the signal as data points in Structure, Structure with time, or Array format. This will create a MAT-file with timestamp information.
To enable this, you will have to select the MAT-file Logging option in the Configuration Parameters dialog box and specify several block parameter values in the output blocks. Once you deploy the code, you can log the signals onto the SD card and later import them into MATLAB for further analysis like fault analysis, searching for transient behavior, or analyzing sensor data.
For detailed information, I recommend referring to Chapter 4 of the documentation: Embedded Coder Support Package for STMicroelectronics STM32 Processors User's Guide (mathworks.com)
