Matlab and Modbus over TCP

Hello there,

i have this code

function [s] = serialstart(opt)
% Funtion for initializing a serial interface in matlab for interfacing

% Functions using the serial port must be passed the serial port object
% s in order for the serial port to be acessable.  

port = 502;  
%   link = tcpip('127.0.0.1',502);  
%   link = tcpip('10.64.15.101',502);  
s = tcpip('192.168.2.177',port);  
%?????  
set(s, 'InputBufferSize', 3000); 

% Initialize serial port on specified com port
date_addr   = 40001;
date_num=1;
date_addr_high = floor(date_addr/100);  
date_addr_low = mod(date_addr,100);  
date_num_high = floor(date_num/100);  
date_num_low = mod(date_num,100); 
%Open serial connection
fopen(s);

 % Specify Terminator
 s.terminator='CR/LF';

fwrite(s,0,'char')                      %Transactio identifier        0x00  
fwrite(s,0,'char')                      %  Transactio identifier                   0x00  
fwrite(s,0,'char')                      %    Protokol identifier      0x00  
fwrite(s,0,'char')                      %        Protokol identifier              0x00  
fwrite(s,0,'char')                      %     Anzahl Datenbytes  0x00  
fwrite(s,1,'char')                      %         Anzahl Datenbytes        0x06  
fwrite(s,255,'char')                     %     unit identifier    0xff  
fwrite(s,3,'uint8')                       %  Funktion           0x03  
fwrite(s,date_addr_high,'uint8')         %Startadresse High Byte   
fwrite(s,date_addr_low,'uint8')            %Startadresse Low Byte
fwrite(s,date_num_high,'uint8')           %Anzahl Register Low Byte
fwrite(s,date_num_low,'uint8')     %Anzahl Register High Byte

while ~s.BytesAvailable
end

s.BytesAvailable
res=fread(s,s.BytesAvailable)                 

fclose(s);

The code should read the data of register 40001 The problem is that i get no response. Matlab doesnt't come back to the prompt.