Receive data from COM

I am trying to make a code that will read data from a COM (in my case TCP/IP connection) every time that the data appears without using an infinite loop or without determining how many times the loop will happen. I’m expecting to receive packets with deferent size. Till now I have only accomplice to receive data with this code:

while 1
  len = s1.BytesAvailable;    % wait to receive a new character

    while len == 0

        len = s1.BytesAvailable;

    end
in = fread(s1,1);
fprintf('\n 1character received %d',in)
end

any help please?