How to read RS232 ?

Honored Contributor

14 years ago

Yes, you are right, i cancel stty command in linux and use

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options.c_lflag &= ~(ICANON | ECHO | ISIG );

in open function:

fd = open(S0_232, O_RDWR | O_NOCTTY | O_NDELAY );

// fd = open(S0_232, O_RDWR); // | O_NOCTTY | O_NDELAY );

if (fd > 0)

{

fcntl(fd, F_SETFL, FNDELAY);

tcgetattr(fd, &options);

options.c_cflag |= (CLOCAL | CREAD );

options.c_cflag &= ~PARENB; // set no parity, stop bits, data bits

options.c_cflag &= ~CSTOPB;

options.c_cflag &= ~CSIZE;

options.c_cflag |= CS8;

options.c_cc[VMIN] = 1;

options.c_cc[VTIME] = 0;

options.c_lflag &= ~(ICANON | ECHO | ISIG );

tcsetattr(fd, TCSANOW, &options);

}

But when i read hex message (from PC to Altera NIOS2 system)

16,11,01,00,00,00,00,80,00,7B

the linux read

16,01,00,00,00,00,80,00,7B

and the second byte doesn't receive .... i read the termios on:

and they say that 0x11 is DC1 which mean VSTART for XON and XOFF and i am not able to disable this software flow control.

When i use setting

options.c_cflag &= ~(IXON | IXOFF | IXANY); // no flow control

options.c_cflag &= ~CRTSCTS;

it doesnt work. Read again:16,01,00,00,00,00,80,00,7B (and the 0x11 is missing).

Do you have somebody program, which can read EVERY characters (hex - 00-FF) without any control meanings ?

Is possible to disable control characters in options.c_cc[xxx] ?

I retype

options.c_cc[VSTART] = 0xFE;

and the message is read ok, but echo was set ... why ?

Where is error ?

Jan, Czech Republic

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