Very Computer

Hi,
        Can someone help me with a problem I'm having reading from the
serial port.
I've set the port up so that anyone can read and write to it. The code
is fine initializing it i.e. no errors etc. I've also been successful
writing to it. When I was to read stuff from it things start going
wacky.

What I want to do is read 25 bytes from the port, into the array and
return. What end up happening is either nothing gets read or random
amounts of data. This is the code I use to read from the port:

...
 nBytesToRead = 25;
 bResult = 0;

 bResult = read(FileHandle, SensorBuffer, nBytesToRead);

 if (bResult == -1) {
        }

 cout << "Actual Char's Read : " << bResult << endl;

 for(int Counter = 0; Counter <= 25; Counter++) {
        cout << SensorBuffer[Counter] << endl;
        }
...

My set up code is:

 FileHandle = open("/dev/ttyS1",O_RDWR | O_NOCTTY | O_NDELAY);

  if (FileHandle == -1)
    cout << "An Error occured while opening Serial Port" << endl;
  else
    cout << "Serial Port opened succesfully" << endl;

  /* Get Current Port Configuration */
  tcgetattr(FileHandle, &options);

  /* Set Baud Rate */
  cfsetispeed(&options,B38400);
  cfsetospeed(&options,B38400);

  options.c_cflag |= (CLOCAL | CREAD);

  /* No Parity, 8 Bits */
  options.c_cflag &= ~PARENB;
  options.c_cflag &= ~CSTOPB;
  options.c_cflag &= ~CSIZE;
  options.c_cflag |= CS8;
  options.c_oflag &= OPOST;

  /* RAW input */
  options.c_lflag &= ~(ICANON | ECHO | ISIG);

  options.c_cc[VMIN] = 25;
  options.c_cc[VTIME] = 0;

  /* Flush buffers */
  tcflush(FileHandle, TCIFLUSH);

  /* Update Port with new Configuration */
  tcsetattr(FileHandle, TCSANOW, &options);

If someone code help me out I'd be most grateful.

Thanks

Mark

There is.  It goes something like this:

 int fd,flags;
 fd = open( name, O_RDWR | O_NDELAY );
 flags = fcntl( fd, F_GETFL, 0 );
 fcntl( fd, F_SETFL, flags & ~O_NDELAY );

Robert

Thank you!  For some reason, I was under the impression that you
couldn't manipulate O_NDELAY with fcntl(); looking at the man page
again, it turns out to be one of only two flags (the other being
O_APPEND) that you *can* manipulate with it.
--
Joseph J. Pfeiffer, Jr., Ph.D.       Phone -- (505) 646-1605
Department of Computer Science       FAX   -- (505) 646-1002
New Mexico State University          http://www.cs.nmsu.edu/~pfeiffer

Thanks for the help, working...no probs !

Mark

Quote:>Hi,
>        Can someone help me with a problem I'm having reading from the
>serial port.
>I've set the port up so that anyone can read and write to it. The code
>is fine initializing it i.e. no errors etc. I've also been successful
>writing to it. When I was to read stuff from it things start going
>wacky.

>What I want to do is read 25 bytes from the port, into the array and
>return. What end up happening is either nothing gets read or random
>amounts of data. This is the code I use to read from the port:

>...
> nBytesToRead = 25;
> bResult = 0;

> bResult = read(FileHandle, SensorBuffer, nBytesToRead);

> if (bResult == -1) {
>        }

> cout << "Actual Char's Read : " << bResult << endl;

> for(int Counter = 0; Counter <= 25; Counter++) {
>        cout << SensorBuffer[Counter] << endl;
>        }
>...

>My set up code is:

> FileHandle = open("/dev/ttyS1",O_RDWR | O_NOCTTY | O_NDELAY);

>  if (FileHandle == -1)
>    cout << "An Error occured while opening Serial Port" << endl;
>  else
>    cout << "Serial Port opened succesfully" << endl;

>  /* Get Current Port Configuration */
>  tcgetattr(FileHandle, &options);

>  /* Set Baud Rate */
>  cfsetispeed(&options,B38400);
>  cfsetospeed(&options,B38400);

>  options.c_cflag |= (CLOCAL | CREAD);

>  /* No Parity, 8 Bits */
>  options.c_cflag &= ~PARENB;
>  options.c_cflag &= ~CSTOPB;
>  options.c_cflag &= ~CSIZE;
>  options.c_cflag |= CS8;
>  options.c_oflag &= OPOST;

>  /* RAW input */
>  options.c_lflag &= ~(ICANON | ECHO | ISIG);

>  options.c_cc[VMIN] = 25;
>  options.c_cc[VTIME] = 0;

>  /* Flush buffers */
>  tcflush(FileHandle, TCIFLUSH);

>  /* Update Port with new Configuration */
>  tcsetattr(FileHandle, TCSANOW, &options);

>If someone code help me out I'd be most grateful.

>Thanks

>Mark

--
Mark