Receive serial data
From: Anders Christensen (andersc1_at_hotmail.com)
Date: 02/23/05
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Date: Wed, 23 Feb 2005 00:02:34 +0100
Hi, I have problem receiving serialdata.
First a short describtion of the context in which I experience the
problem: I have a barcodescanner connected to my PC via a RS-232/RS-485
network using ICP CON modules 7520 and 7522. The purpose of this network
is to be able to use several RS-232-devices from one serialport. From my
PC I have only one serialport open which connects to the 7520-module.
Reading and writing the different RS-232-devices is a matter of
sending an appropriate command telling the 7520-module to read/write which
serialbuffer. The manufactor of the ICP CON modules has made a function
for that under Linux; i7k_send_readt().
Now on to the actual problem
I can from my PC read the serialbuffer of the barcodescanner, but
sometimes one barcode is splitted into several reads. And sometimes a
<CR> is received as the first character of the barcode. What can I do to
avoid this?
Below I paste
1) A print from the terminal to illustrate the problem
2) The source-code of my test-main
3) The function sio_open
Hope that someone has an idea on what the problem might be. I'd be glad to
hear any suggestion.
./Anders.
________________Print from the terminal:
[root@dhcp231 examples]# ./send_read
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=8: 48 48 57 51 54 54 48 13
r=6: 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=5: 48 48 57 51 13
r=9: 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=6: 48 48 57 51 54 13
r=8: 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=14: 10 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 48 48 57 51 54 54 48 48 48 49 57 54 13
r=14: 10 48 48 57 51 54 54 48 48 48 49 57 54 13
r=14: 10 48 48 57 51 54 54 48 48 48 49 57 54 13
r=13: 10 48 48 57 51 54 54 48 48 48 49 57 13
________________Source-code of my test-main:
#include "i7k.h"
#define RCVBUF_SIZE 128
int main()
{
int fd;/* file descriptor */
char *cmd;/* point to command string */
char rbuf[RCVBUF_SIZE];/* receive buffer */
__tod_t texp;/* to receive the expended time */
int r, i;
fd = sio_open("/dev/ttyS0", B9600, DATA_BITS_8, NO_PARITY,
ONE_STOP_BIT);
if (fd == ERR_PORT_OPEN) {
printf("open port failed!\n");
return (-1);
}
cmd = "$01U\r"; //command for reading from my barcode-buffer
while(1) {
usleep(100000);
r = i7k_send_readt(fd, cmd, rbuf, RCVBUF_SIZE-1, &texp);
if (r>2) {
printf("r=%i: ",r);
for (i=0;i<r;i++) printf("%i ", (int)rbuf[i]);
printf("\n");
}
}
sio_close(fd);
return (0);
}
________________Function sio_open:
/**********************************************************************
* sio_open
*
* Open and initiate serial port
* default open port in noncanonical mode
*
* Arguments:
* port a string point to the name of serial device,
* such as "/dev/ttyS0"
* baud B0, B50... B9600, B19200, B38400...
* data Data bit(s), unsigned char
* parity Parity, unsigned char
* stop Stop bit(s), unsigned char
*
* Returned:
* This function returns int port descriptor for the port opened
* successfully. Return value ERR_PORT_OPEN if failed.
*
**********************************************************************/
int
sio_open(const char *port, speed_t baud, tcflag_t data, tcflag_t parity,
tcflag_t stop)
{
struct sio *sio; /* point to current sio structure */
int fd; /* file descriptor for current port */
int r;
struct termios *options; /* options for current port */
PDEBUG("sio_open: start\n");
/***************
* open port *
***************/
fd = _sio_device(port);
if (fd == 0) { /* device is not yet opened, so, open it */
// fd = open(port, O_RDWR | O_NOCTTY | O_NDELAY);
fd = open(port, O_RDWR | O_NOCTTY | O_NONBLOCK);
}
PDEBUG(" fd = %u\n", fd);
if (fd == -1) { /* Could not open the port */
PDEBUG("sio_open: Unable to open %s - %s\n", strerror(errno),
port);
return (ERR_PORT_OPEN);
}
/********************************
* allocate new sio structure *
********************************/
sio = _sio_follow(fd);
if (!sio) { /* out of memory */
close(fd);
return (ERR_PORT_OPEN);
}
sio->fd = fd;
sio->name = port;
// fcntl(fd, F_SETFL, FNDELAY); /* nonblocking */
tcgetattr(fd, sio->old_options); /* save the original options */
tcgetattr(fd, sio->options); /* Get the current options */
options = sio->options;
/*
* printf("\nsio_open\n"); printf("name : %s\n", sio->name);
* printf("fd : %d\n", fd); printf("sio : %lx\n", sio);
* printf("sio->options : %lx\n", sio->options);
* printf("sio->old_options : %lx\n", sio->old_options);
* printf("options : %lx\n", options); printf("\n");
*/
/*********************
* select Baudrate *
*********************/
r = cfsetispeed(options, baud); /* input */
if (r) {
PDEBUG("sio_open: fails to set input baudrate!\n", r);
close(fd);
return (r);
}
r = cfsetospeed(options, baud); /* output */
if (r) {
PDEBUG("sio_open: fails to set output baudrate!\n", r);
close(fd);
return (r);
}
/**********************
* select data bits *
**********************/
options->c_cflag &= ~CSIZE; /* bit mask for data bits */
options->c_cflag |= data;
/*
* close(fd); PDEBUG("undefined data bits number %d, port %s
* closed.\n", data, port); return (ERR_PORT_OPEN);
*/
/*******************
* select parity *
*******************/
switch (parity) {
case NO_PARITY:
options->c_cflag &= ~(PARENB | PARODD);
break;
case ODD_PARITY:
options->c_cflag |= PARODD;
break;
case EVEN_PARITY:
options->c_cflag |= PARENB;
break;
default:
tcsetattr(fd, TCSANOW, sio->old_options);
close(fd);
_sio_trim(fd);
PDEBUG("undefined parity code %d, port %s closed.\n", parity,
port);
return (ERR_PORT_OPEN);
}
/************************
* select stop bit(s) *
************************/
switch (stop) {
case ONE_STOP_BIT:
options->c_cflag &= ~CSTOPB;
break;
case TWO_STOP_BITS:
options->c_cflag |= CSTOPB;
break;
default:
tcsetattr(fd, TCSANOW, sio->old_options);
close(fd);
_sio_trim(fd);
PDEBUG("undefined stop bits code %d, port %s closed.\n", stop,
port);
return (ERR_PORT_OPEN);
}
/**********************
* other parameterm *
**********************/
/*
* posix input mode flags
*/
options->c_iflag &= ~ICRNL; /* disable map CR to NL for noncanonical */
options->c_iflag &= ~INLCR;
options->c_iflag &= ~IXON; /* disable software flow control
* (outgoing) */
options->c_iflag &= ~IXOFF; /* disable software flow control
* (incoming) */
/*
* posix output mode flags
*/
options->c_oflag &= ~OPOST; /* raw output */
options->c_oflag &= ~OLCUC; /* do not transfer the case */
options->c_oflag &= ~ONLCR; /* do not translate the CR and NL */
options->c_oflag &= ~OCRNL;
options->c_oflag &= ~NLDLY; /* no delay for NL */
options->c_oflag &= ~CRDLY; /* no delay for CR */
options->c_oflag &= ~TABDLY; /* no delay for TAB */
options->c_oflag &= ~BSDLY; /* no delay for BS */
options->c_oflag &= ~VTDLY; /* no delay for VT */
options->c_oflag &= ~FFDLY; /* no delay for FF */
/*
* posix control mode flags
*/
options->c_cflag |= CLOCAL; /* Local line */
/*
* do not change "owner" of port
*/
options->c_cflag |= CREAD; /* Enable receiver */
options->c_cflag &= ~CRTSCTS; /* Disable hardware flow control */
/*
* posix local mode flags
*/
options->c_lflag &= ~ICANON; /* default for noncanonical mode */
options->c_lflag &= ~ECHO; /* Disable echoing of input characters */
options->c_lflag &= ~ISIG; /* disable signals */
/*
* posix control characters
*/
options->c_cc[VINTR] = 0;
options->c_cc[VQUIT] = 0;
options->c_cc[VERASE] = 0;
options->c_cc[VKILL] = 0;
options->c_cc[VEOF] = 4;
options->c_cc[VTIME] = 0; /* Time to wait for data (tenths of
* seconds) */
options->c_cc[VMIN] = 1;//Anders: var foer 1
options->c_cc[VSWTC] = 0;
options->c_cc[VSTART] = 0;
options->c_cc[VSTOP] = 0;
options->c_cc[VSUSP] = 0;
options->c_cc[VEOL] = 0;
options->c_cc[VREPRINT] = 0;
options->c_cc[VDISCARD] = 0;
options->c_cc[VWERASE] = 0;
options->c_cc[VLNEXT] = 0;
options->c_cc[VEOL2] = 0;
/**************************************
* set the new options for the port *
**************************************/
// tcsetattr(fd, TCSANOW, options);
tcsetattr(fd, TCSAFLUSH, options); /* flush input and output buffers,
* and make the change */
# ifdef I7K_DEBUG
_sio_poptions(fd);
# endif /* I7K_DEBUG */
return (fd);
}
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