I solved the problem. I used to matfile from the sinks library and created the subsystem for this block. Then i masked the subsystem as parameter -- Inherit: Same as output Parameter name must be the same with output name . In my genetic algorithm .m file i used
y = get_param('my_model/y','y') %y is also subsystem name
it works. After running the simulation i get the y values each iteration to send ga .m file for optimization.