Before simulating a model, define the external interfaces for the model, including input and output signals. Input signals load data into the model for simulation, while output signals allow you to record simulation results. Simulink® supports many formats for signal data. You can load signal data that you create in MATLAB® or a spreadsheet or that you save during simulation. The kind of signal data you want to load impacts your choice of signal loading techniques.
For an overview of how to use MATLAB data in Simulink models, save simulation data, and log signals for analysis, watch Loading and Logging Data (4 min, 9 sec) and see Provide Signal Data for Simulation..