Simulink Desktop Real-Time™ provides a real-time kernel for executing Simulink® models on a laptop or desktop running Windows® or Mac OS X. It includes library blocks that connect to a range of I/O devices. You can create and tune a real-time system for rapid prototyping or hardware-in-the-loop simulation with your computer.
Simulink Desktop Real-Time supports real-time performance up to 1 kHz sample rates with Simulink, and up to 20 kHz with Simulink Coder™.
From Nikhil Rai, Simulink Desktop Real-Time Technical Expert