Simulink pixhawk HITL

Hi everyone, I am working on a project on MATLAB/Simulink. I modeled a quadrotor slung load system in Simulink and for this model I developed a PID controller. Now I'm trying to implement it on a pixhawk flight controller. Before testing it in real time I wish to perform HITL simulations. I've never done anything similar before, hence wanted to ask for help. If anyone could help me with it, it would be great.