tcpip connection with pnet

We use TCP/UDP/IP Toolbox 2.0.5 to read and write data from/to a TCPIP port. It’s fast and reliable. The version we use is 2.0.5. Below is a matlab sample script showing how to connect to another computer (called ETG-4000) with TCPIP :

%Connect LAN Port
fid=pnet('tcpconnect','172.17.101.1',51027);

if pnet(fid,'status')==-1
  disp('Connection Failed.');
  return;
end;

%Write to port (i.e. Send Command for ETG-4000)
pnet(fid,'printf','++Hello ETG-4000\r\n');

%Read from port (i.e. Receive Command from ETG-4000)
welcomeMessage = pnet(fid,'read',74); 

disp('Press ETG-4000 START Button!');

%//////////////////////// Get ETG-4000 Data ////////////////////////////////
while(1);
            buff1=pnet(fid,'read',4, 'uint8');
            hsize=bread(buff1,'int32');

            if hsize==12;%Data is comming!
                %disp('hsize is 12');
                %///////////////////////// Data Number ///////////////////////////////
                buff2=pnet(fid,'read',4, 'uint8');
                num=bread(buff2,'int32');%Number of Data
                %disp(['num: ' num]);

                %disp(['num of buff2 ' num2str(num)]);
                %//////////////////////////// Data Size:428 ////////////////////////////
                buff3=pnet(fid,'read',4, 'uint8');
                dsize=bread(buff3,'int32');
                %disp(['dsize ' dsize]);
                %/////////////////////////// Hb Data ////////////////////////////////
                for ch=1:52;%Oxy
                    buff4=pnet(fid,'read',4, 'uint8');
                    oxy(ch,num)=bread(buff4,'single');
                %    disp(oxy(ch,num));
                end;
                for ch=1:52;%Deoxy
                    buff5=pnet(fid,'read',4, 'uint8');
                    deo(ch,num)=bread(buff5,'single');
                end;

                %//////////////////////////// Mark ///////////////////////////////
                buff6=pnet(fid,'read',2, 'uint8');
                mark(num)=bread(buff6,'int16');

                %/////////////////////////// Time ////////////////////////////////
                buff7=pnet(fid,'read',10);
                time(num,:)=char(buff7);
                %disp(time(num,:))

          end;
          %(check status) Push ETG-4000 Stop Button
          stat=pnet(fid,'status');
          if(stat == 0)
            break;
          end
end;

pnet('closeall');
clear fid;

bread is a function to convert binary data to a certain data type:

function y = bread(x, type)
y = typecast(x, type); % work for pnet

One important thing is you need specify the 4th parameter (datatype) when you read data in pnet(‘read’). The default value is ‘char’ and if your incoming data is float, you will find any value in a byte which is bigger than 127 is reset to 255. Specifying the 4th parameter to ‘uint8’ solves this problem. I spend a day to find this.

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