Protocole communication *µcontroller <=> Matlab

Hello

I would like to send an order on the map in hexadecimal formats like this : 0x100x000x03 and I'd like to have this same format back.

But , I receive nothing in return an error

My programme matlab

s=serial('COM4');
set(s,'BaudRate',9600,'DataBits', 8, 'Parity', 'none','StopBits', 1, 'FlowControl', 'none','Terminator','CR')

% Connect to instrument object, obj1.

fopen(s);

% pause(2)

% fprintf(s,'0x100x000x03 ')

% pause (2)

% fscanf(s)
% data=fscanf(s);
% data=str2num(data); 
% 
% display(data)

fclose(s);

The error is :

warning: A timeout occurred before the Terminator was reached.

Is this program correct because I think that format inside fprintf is not good!

thanks