1. 이런식으로 보낼 수 있습니다.
뭐 스트링말고 버퍼는 함수만 바꾸면 됩니다.

            try
              IdTCPClientCDI.IOHandler.Write(asTemp);
            except
              on E : EIdException do
              begin
                try
                  if EIdSocketError(E).LastError = 10054 then
                    Disconnect
                  else if E.Message = 'Connection Closed Gracefully.' then
                    Disconnect;
                except

                end;
              end;
            end;




2. 읽을땐

if Connected = True then
      begin
        try
          //////////
          // Receive

          asLine := IdTCPClientCDI.IOHandler.ReadString(IdTCPClientCDI.IOHandler.InputBuffer.Size);

          //if IdTCPClientCDI.IOHandler.InputBufferIsEmpty then
          //  IdTCPClientCDI.IOHandler.CheckForDataOnSource(100);

          //if IdTCPClientCDI.IOHandler.InputBufferIsEmpty = False then
          //  asLine := IdTCPClientCDI.IOHandler.InputBuffer.Extract(IdTCPClientCDI.IOHandler.InputBuffer.Size);
          //  asLine := IdTCPClientCDI.IOHandler.InputBuffer.ExtractToString;

          //IdTCPClientCDI.IOHandler.CheckForDisconnect(True);
        except
          on E : EIdException do
          begin
            try
              if EIdSocketError(E).LastError = 10054 then
                Disconnect
              else if E.Message = 'Connection Closed Gracefully.' then
                Disconnect
              else
                asLine := '';
            except

            end;
          end;
        end;