Re: Newbie problem

[Bahadir Karuv <bahkar@bcacademies.bergen.org>]

Hi Ed,

Thanks again for replying, I was wearing the mouse button, clicking New
Msg icon.
It is RS232,  Dell Optiplex COM1.
Best regards.

Karuv

Ed Vance wrote:

> Hi Karuv,
>
> Is it not RS-232 interface? RS-485/422 2-wire will do this because the
>
> transmit and receive pairs are the same pair.
>
> Regards,
> Ed
>
> ----------------------------------------------------------------
> Ed Vance              edv@macrolink.com
> Macrolink, Inc.       1500 N. Kellogg Dr  Anaheim, CA  92807
> ----------------------------------------------------------------
>
> -----Original Message-----
> From: Bahadir Karuv [mailto:bahkar@bcacademies.bergen.org]
> Sent: Thursday, April 25, 2002 10:12 AM
> To: Ed Vance; linux-serial@vger.kernel.org
> Subject: Re: Newbie problem
>
> Hi Ed,
>
> Thanks for the speedy response. I thought the same but the first
> computer keeps getting whatever it is sending ("Hello") eventhough the
>
> serial cable is disconnected. The program I sent is running on the
> first
> computer.
>
> Thanks again and regards,
>
> Karuv
>
> Ed Vance wrote:
>
> > Hi,
> >
> > My guess is that the second computer has "echo" enabled so all
> > characters
> > received are echoed back to the other end. I see you turn echo off
> in
> > the
> > program. I am assuming that the program is only running on the first
>
> > computer.
> >
> > Regards,
> > Ed
> >
> > ----------------------------------------------------------------
> > Ed Vance              edv@macrolink.com
> > Macrolink, Inc.       1500 N. Kellogg Dr  Anaheim, CA  92807
> > ----------------------------------------------------------------
> >
> > -----Original Message-----
> > From: Bahadir Karuv [mailto:bahkar@bcacademies.bergen.org]
> > Sent: Thursday, April 25, 2002 8:59 AM
> > To: linux-serial@vger.kernel.org
> > Subject: Newbie problem
> >
> > Hello All,
> >
> > I am trying to have to computers communicate over the serial port.
> > The program below is modified from "Serial Programming Guide for
> Posix
> >
> > operating Systems"
> > I am geting the following output when I send "Testing123" over the
> > serial port from the second computer
> >
> > opened 3
> > just sent Hello
> > got back - Hello
> > just sent Hello
> > got back - HelloTesting123
> > just sent Hello
> > got back - Hello
> >
> > First computer is getting the string echoed back to itself after it
> > sends "Hello".
> >
> > What am I doing wrong?
> >
> > Thanks and regards!
> >
> >
> >
> > #include <stdio.h>
> > #include <unistd.h>
> > #include <fcntl.h>
> > #include <termios.h>
> > #include <string.h>
> >
> > int main(void)   /* Serial port */
> >        {
> >  time_t tsec;
> >  int fd;
> >  struct termios options;
> >  char buffer[255];
> >  char *bufptr;
> >  int  nbytes;
> >  char *message="Hello";
> >
> >  /* open the port */
> >  fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
> >  //fcntl(fd, F_SETFL, FNDELAY);
> >  printf("opened %u\n",fd);
> >  /* options */
> >  tcgetattr(fd, &options);
> >  options.c_cflag     |= (CLOCAL | CREAD);
> >  options.c_lflag     &= ~(ICANON | ECHO | ECHOE | ISIG);
> >  options.c_oflag     &= ~OPOST;
> >  options.c_cc[VMIN]  = 0;
> >  options.c_cc[VTIME] = 10;
> >  tcsetattr(fd, TCSANOW, &options);
> >  /* read characters into our string buffer until CR or NL */
> >  while(1){
> >  write(fd, message,strlen(message));
> >  printf("just sent %s\n",message);
> >  tsec=time(NULL);
> >  while(time(NULL)-tsec<1);
> >
> >  bufptr = buffer;
> >  buffer[0]='\0';
> >  while ((nbytes = read(fd, bufptr, bufptr-buffer +
> sizeof(buffer)-1))
> > >
> > 0)
> >  {
> >   bufptr += nbytes;
> >   if (bufptr[-1] == '\n' || bufptr[-1] == '\r')
> >    { printf("break\n");break;}
> >  }
> >  if (buffer!=bufptr){
> >    *(bufptr) = '\0';
> >    printf("got back - %s\n",buffer);
> >  }
> >     }
> >     close(fd);
> > }
> >
> >
> > -
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