[SOLVED] C++ serial comunication problem

[mattiaxx86to]

Hi at all and very compliments for the great forum!

I have a little (big) problem with a program, because
open the comunication, read buffer, but returns
strange characters.
I think it's a ttyS0 configuration,
for comunicate i want to use this parameters:

Baud : 4800
Parity : Event
StopBit : 1
No flow control data bits 7

This is the code :

// simple program to open the comm port, read data, save the raw data to a file.
//
// accumulates statistics for each group of 1,000 reads
//
// for each 1,000 reads, displays the number of bytes received
// and the largest number of bytes in a single read
 
#include <cerrno>
#include <cstdio>
#include <cstdlib>
#include <fcntl.h>
#include <iostream>
#include <memory.h>
#include <termios.h>
#include <sys/ioctl.h>
 
int main(int argc, char **argv)
{
 int fd_port, fd_file;
 int max_read;    // maximum read line (in 1000 reads)
 int read_count;  // number of port reads
 int total_read;  // total bytes received from the port
 int bytes_read;  // total bytes received (in 1000 reads)
 
 // allow setting vmin and vtime from the command line
 int vmin  = (argc < 3) ? 1 : atoi(argv[1]);
 int vtime = (argc < 3) ? 0 : atoi(argv[2]);
 
 struct termios options;
 
 // open output file
 fd_file = open("comm2.bin", O_WRONLY|O_CREAT);
 fprintf(stderr, "fd_file %d\n", fd_file);
 
 // open comm 2
 fd_port = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NONBLOCK);
 fprintf(stderr, "fd_port %d\n", fd_port);
 
 // Configure port settings
 fcntl(fd_port, F_SETFL, O_NONBLOCK * 0 );
 
 // Save current port settings so we don't corrupt anything on exit
 
 memset(&options,0,sizeof(options));
 tcgetattr(fd_port, &options);
 options.c_cc[VMIN] = vmin;
 options.c_cc[VTIME] = vtime; // t * 0.1s
 fprintf(stderr, "vmin %d, vtime %d\n", options.c_cc[VMIN], options.c_cc[VTIME]);
 
 options.c_iflag |= PARMRK; // 0000010
 
// set baud rate
 cfsetispeed(&options, B4800);
 cfsetospeed(&options, B4800);
 
 options.c_cflag |= (CLOCAL | CREAD);
 
 // clear mark/space parity
 options.c_cflag &= ~CMSPAR;
 
 // clear character size, stop bit count, and parity setting
 options.c_cflag &= ~(CSIZE|CSTOPB|PARENB|PARODD);
 
 // No parity, 1 stop bit (8N1), 8 data bits.
 options.c_cflag |= CS7;
 
 // Turn off hardware flow control
// options.c_cflag &= ~CRTSCTS;
 
 // Turn on hardware flow control
 options.c_cflag |= CRTSCTS;
 
 options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
 
 tcflush(fd_port, TCIFLUSH);
 
 // Write changes to the port configuration
 tcsetattr(fd_port, TCSANOW, &options);
 
 /* Drop RTS to enable receiver */
 int flags = TIOCM_RTS;
 ioctl( fd_port, TIOCMBIC, &flags );
 
 // initialize counters
 max_read = read_count = total_read = bytes_read = 0;
 
 while (total_read < 200000)
 {
  unsigned char buff[256];
 
  // read bytes
  int cnt = read(fd_port, &buff, sizeof(buff));
 
  // save bytes
  write(fd_file, &buff, cnt);
 
  // accumulate statistics
  if (cnt > 0)
  {
   read_count += 1;
   bytes_read += cnt;
   total_read += cnt;
   if (cnt > max_read)
    max_read = cnt;
   // display statistics every 1000 reads
   if (read_count == 1000)
   {
    printf( "max: %3d, tot: %5d\n", max_read, bytes_read );
    max_read = read_count = bytes_read = 0;
   }
  }
 }
 
 // close comm port
 close(fd_port);
 
 // close output file
 close(fd_file);
 
 return 0;
}

Can anyone help me to set this parameter in this code?

Thanks at all

[Rubberman]

Tell us a bit more about what you are communicating with, and why you think the received data contains "strange" characters.

[mattiaxx86to]

I want to comunicate via serial port with a laser,
this return this type of string:

DA12543789

Received data contains strange character because
the received typical string is (witch CS8 setting) :

DA30...t.F.

With CS7 setting :

AwIudf89 u73jsa. q927qw30rhasvp

But i don't understand why, if i open the comport with
a terminal i can see the correct string

[Rubberman]

What settings does the terminal use? IE, what are the default settings on /dev/ttyS1? You can see with the terminal command stty </dev/ttyS1.

[mattiaxx86to]

Thanks for all, i have solve my problem.

I miss to insert the correct parity configuration

options.c_cflag |= PARENB;

and i miss to clear the buffer after reading,
for this the array contains strange character.

//clear buffer
  for(int index = 0; index < 256 ; index++)
  {
   buff[index] = NULL;
  }

See you