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Top Forums Programming Wrong data with Read from a serial port. Post 302730495 by enaud on Tuesday 13th of November 2012 04:37:24 AM
Old 11-13-2012
Wrong data with Read from a serial port.

hi, I've a problem on my C/C++ program with Posix Library.

I have to read data from the serial but I have incorrect data, in fact I get a bunch of zeros:
"2953.3174, 2785.2126, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0 , 0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 , 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0 , 0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 , 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0 , 0, 0,0, "

I should get something like this:

3087,3102,2492,1860,1403,1074,1004,1468,2152,2645,3007,3143,2714,2006,1503,1148,971,1308,1998,2536,2 925,3163,2884,2182,1625,1234,979,1170,1820,2411,2834,3135,3013,2381,1721,1328,1021,1076,1646,2290,27 46,3079,3115,2589,1901,1430,1095,1001,1442,2128,2630,2994,3156,2758 ETC...

My class that i use is this:


Code:
int cClassSerialLIB::ReadPort(/*QChar * Response*/)
{
     long int iIn;

     counter_uart2 =0;

     for (int i=0;i<6000;i++)
         array_uart2[i]='\0';

     
       if (fd < 1)
       {
           printf(" port is not open\n");
           return -1;
       } 

       iIn = read(fd, array_uart2, sizeof(array_uart2));

       static int count=0;

       if (iIn < 0)
       {
           if (errno == EAGAIN)
           {         
                   //qDebug("Read nothing");
                   return 0; // assume that command generated no response
           }
           else
           {
                   printf("read error %d %s\n", errno, strerror(errno));
           } 
       }

       counter_uart2=iIn;
       return iIn;
}


and open function:


Code:
bool cClassSerialLIB::OpenPort(bool bloccante)
{
      // make sure port is closed
      ClosePort();
      //ttymxc4
      QByteArray Porta_byte_array = Porta.toLatin1();
      const char* Porta_char=Porta_byte_array.data();
      fd = open(Porta_char/*"/dev/ttymxc4"*/, O_RDWR |
                          O_NOCTTY | /* tells UNIX that this program doesn't want to be the "controlling terminal" for that port*/
                          O_NDELAY); /* tells UNIX that this program doesn't care what state the DCD signal line is in */

      if (fd < 0)
      {
          qDebug("errore in apertura %d %s\n", errno, strerror(errno));
          return false;
      }
      else
      {
          qDebug("ok %d",fd);
          struct termios options;

          /* The FNDELAY option causes the read function to return 0 if no
            characters are available on the port. To restore normal (blocking) behavior,
            call fcntl() without the FNDELAY option: */

          if(bloccante)
          {
              printf("bloccante\n");
              fcntl(fd, F_SETFL, 0);
          }
          else
          {
             printf("NON bloccante");
             fcntl(fd, F_SETFL, FNDELAY);
          }

          //cfmakeraw(&options); //ABILITARLO NEL CASO DI ERRORE!


          tcgetattr(fd, &options);

          //set port speed 115200
          cfsetispeed(&options, B115200);
          cfsetospeed(&options, B115200);

          options.c_cflag |= (CLOCAL | CREAD);

          //set 8n1

          options.c_cflag &= ~PARENB; /* Enable parity bit */
          options.c_cflag &= ~CSTOPB; /* 2 stop bits (1 otherwise) */
          options.c_cflag &= ~CSIZE; /* Mask the character size bits */
          options.c_cflag |= CS8; /* Select 8 data bits */

          options.c_iflag &= ~IXON; //RIMUOVE X0N/XOFF control
          options.c_iflag &= ~IXOFF;
          options.c_iflag &= ~IGNCR;

          //set raw input
          options.c_lflag &= ~(ICANON |   /*Enable canonical input (else raw)*/
                                  ECHO |  /*Enable echoing of input characters*/
                                  ECHOE | /*Echo erase character as BS-SP-BS*/
                                  ISIG);  /*Enable SIGINTR, SIGSUSP, SIGDSUSP, and SIGQUIT signals*/


          tcsetattr(fd, TCSANOW, &options); /*Make changes now without waiting for data to complete*/

      }
      return true;
}

how i must set option in open function? thanks..
 

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