Arduino Simulink function pulsIn

Dear all, I try to use an ultrasonic sensor (HC-SR04) on my Arduino mega2560 with Simulink (Matlab 2015a). For this I need to read the Echo signal, which returns me the duration (width of Echo pulse), which is an image of the distance. Normally, we use “pulsIn” function, but this function is not standard in Mathworks package (Simulink). Someone has developed the s-function to perform in Simulink this “pulsIn” function? Thank you by advance Vincent