int read_datas_tty(int fd,char *rcv_buf,int sec,int usec)
{
int retval;
unsigned char tempchar2;
fd_set rfds;
struct timeval tv;
int ret,pos;
tv.tv_sec = sec;//set the rcv wait time
tv.tv_usec = usec;//100000us = 0.1s
while(1){
   FD_ZERO(&rfds);
   FD_SET(fd,&rfds);
   retval = select(fd+1,&rfds,NULL,NULL,&tv);
   if(retval ==-1)
   {
    perror("select()");
    break;
   }
   else if(retval)
   {
    ret= read(fd,rcv_buf,1);
tempchar2 = rcv_buf;
printf("rcv_buf is %s\n",rcv_buf);
        
   }
   else
   {
    break;
   }
}
return 1;  
}

bool ReadDevice( int hComm, unsigned long uLen, char* pData )

{  

    int      nread = 0;

   char   inbuf[uLen];

   char  buff[uLen];

   memset( inbuff,  '\0', uLen );

   memset( buff, '\0', uLen );

   fd_set readset;
   struct timeval tv;
   int MaxFd = 0;

   int c = 0;
   int z;
   do
   {
       FD_ZERO( &readset );
       if( hComm >= 0 )
       FD_SET( hComm, &readset );
       MaxFd = hComm + 1;
       tv.tv_sec = 0;
       tv.tv_usec = 500000;
      do
      {
           z = select( MaxFd, &readset, 0, 0, &tv);
      }while( z==-1 && errno==EINTR );
      if( z == -1 )
           printf("select(2)\n");
      if( z == 0 )
      {
          hComm = -1;
      }
  
      if( hComm>=0 && FD_ISSET(hComm, &readset) )
      {
           z = read( hComm, buff, uLen - c );
           c += z;
           if( z == -1 )
           {
               hComm = -1;
           }
           if( z > 0 )
          {

                buff[ z + 1 ] = '\0';
                strcat( inbuff, buff );
                memset( buff, 0x00, uLen );
           }
           else
          {
               hComm = -1;
          }
      }
   }while( hComm >= 0 );

   memcpy( pData, inbuff, c );

   return true;

}