Efficient real-time data streaming between two PCs.

Dear all,

I am trying to read data in real-time using TCP/IP from a remote PC which has an application running to record some data. The following code helps reading each data item at "a time". The problem is that when you want to get more data items you have to run the following four lines again with different data number (which here is 13), this takes too long for each sample of data so it misses some data between each readings. For instance if the data items are provided every 0.003 sec it reads the data every 0.01 sec so missing at least two samples in this 0.007 sec interval.

      flushinput(t); %clear input buffer
      GetDataItem(t,13); %send command to the remote PC
      InputBuf = fread(t,40); %read 1st 40bytes sent back by the remote PC
      data(sampl_cnt) = fread(t,1,'single'); %read floating point value starting at byte 41

This is the subroutine function to send a command to the application in the remote PC to choose a data item

function GetDataItem(t, DataID)
  GetDataItem_cmd = 25;

    output_bytes = [76,83,65,32,20,0,0,0,GetDataItem_cmd,0,0,0,0,0,0,0,DataID,0,0,0];

     % compute check sum
      %  First, sum the bytes in the output array
      sum = int32(0);
      for count = 1:20; 
          incr = int32(output_bytes(count));
          sum = sum + incr;
      end
      %  Get the least significant byte of the sum
      sum16 = uint16(sum);
      sum_lsb = bitand(sum16,255);
      %  Take the "twos compliment" of the lsb
      chksm = bitcmp(uint8(sum_lsb),'uint8') + 1;
      %  insert the checksum in the output array  
      output_bytes(13) = chksm;
      fwrite(t,output_bytes);
  end

Do you have any suggestions to optimize the codes to run faster or do you think it is possible to take multiple data items at a time?