libmbus/mbus/mbus-serial.c

240 lines
6.4 KiB
C

//------------------------------------------------------------------------------
// Copyright (C) 2011, Robert Johansson, Raditex AB
// All rights reserved.
//
// rSCADA
// http://www.rSCADA.se
// info@rscada.se
//
//------------------------------------------------------------------------------
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <stdio.h>
#include <strings.h>
#include <termios.h>
#include <errno.h>
#include <string.h>
#include <mbus/mbus.h>
#include <mbus/mbus-serial.h>
#define PACKET_BUFF_SIZE 2048
//------------------------------------------------------------------------------
/// Set up a serial connection handle.
//------------------------------------------------------------------------------
mbus_serial_handle *
mbus_serial_connect(char *device)
{
mbus_serial_handle *handle;
if (device == NULL)
{
return NULL;
}
if ((handle = (mbus_serial_handle *)malloc(sizeof(mbus_serial_handle))) == NULL)
{
fprintf(stderr, "%s: failed to allocate memory for handle\n", __PRETTY_FUNCTION__);
return NULL;
}
handle->device = device; // strdup?
//
// create the SERIAL connection
//
// Use blocking read and handle it by serial port VMIN/VTIME setting
if ((handle->fd = open(handle->device, O_RDWR | O_NOCTTY)) < 0)
{
fprintf(stderr, "%s: failed to open tty.", __PRETTY_FUNCTION__);
return NULL;
}
bzero(&(handle->t), sizeof(handle->t));
handle->t.c_cflag |= (CS8|CREAD|CLOCAL);
handle->t.c_cflag |= PARENB;
// No received data still OK
handle->t.c_cc[VMIN] = 0;
// Wait at most 0.2 sec.Note that it starts after first received byte!!
// I.e. if CMIN>0 and there are no data we would still wait forever...
//
// The specification mentions link layer response timeout this way:
// The time structure of various link layer communication types is described in EN60870-5-1. The answer time
// between the end of a master send telegram and the beginning of the response telegram of the slave shall be
// between 11 bit times and (330 bit times + 50ms).
//
// For 2400Bd this means (330 + 11) / 2400 + 0.05 = 188.75 ms (added 11 bit periods to receive first byte).
// I.e. timeout of 0.2s seems appropriate for 2400Bd.
handle->t.c_cc[VTIME] = 2;
cfsetispeed(&(handle->t), B2400);
cfsetospeed(&(handle->t), B2400);
#ifdef MBUS_SERIAL_DEBUG
printf("%s: t.c_cflag = %x\n", __PRETTY_FUNCTION__, handle->t.c_cflag);
printf("%s: t.c_oflag = %x\n", __PRETTY_FUNCTION__, handle->t.c_oflag);
printf("%s: t.c_iflag = %x\n", __PRETTY_FUNCTION__, handle->t.c_iflag);
printf("%s: t.c_lflag = %x\n", __PRETTY_FUNCTION__, handle->t.c_lflag);
#endif
tcsetattr(handle->fd, TCSANOW, &(handle->t));
return handle;
}
//------------------------------------------------------------------------------
//
//------------------------------------------------------------------------------
int
mbus_serial_set_baudrate(mbus_serial_handle *handle, int baudrate)
{
if (handle == NULL)
return -1;
switch (baudrate)
{
case 300:
cfsetispeed(&(handle->t), B300);
cfsetospeed(&(handle->t), B300);
return 0;
case 1200:
cfsetispeed(&(handle->t), B1200);
cfsetospeed(&(handle->t), B1200);
return 0;
case 2400:
cfsetispeed(&(handle->t), B2400);
cfsetospeed(&(handle->t), B2400);
return 0;
case 9600:
cfsetispeed(&(handle->t), B9600);
cfsetospeed(&(handle->t), B9600);
return 0;
default:
return -1; // unsupported baudrate
}
}
//------------------------------------------------------------------------------
//
//------------------------------------------------------------------------------
int
mbus_serial_disconnect(mbus_serial_handle *handle)
{
if (handle == NULL)
{
return -1;
}
close(handle->fd);
free(handle);
return 0;
}
//------------------------------------------------------------------------------
//
//------------------------------------------------------------------------------
int
mbus_serial_send_frame(mbus_serial_handle *handle, mbus_frame *frame)
{
u_char buff[PACKET_BUFF_SIZE];
int len, ret;
if (handle == NULL || frame == NULL)
{
return -1;
}
if ((len = mbus_frame_pack(frame, buff, sizeof(buff))) == -1)
{
fprintf(stderr, "%s: mbus_frame_pack failed\n", __PRETTY_FUNCTION__);
return -1;
}
#ifdef MBUS_SERIAL_DEBUG
// if debug, dump in HEX form to stdout what we write to the serial port
printf("%s: Dumping M-Bus frame [%d bytes]: ", __PRETTY_FUNCTION__, len);
for (i = 0; i < len; i++)
{
printf("%.2X ", buff[i]);
}
printf("\n");
#endif
if ((ret = write(handle->fd, buff, len)) != len)
{
fprintf(stderr, "%s: Failed to write frame to socket (ret = %d: %s)\n", __PRETTY_FUNCTION__, ret, strerror(errno));
return -1;
}
return 0;
}
//------------------------------------------------------------------------------
//
//------------------------------------------------------------------------------
int
mbus_serial_recv_frame(mbus_serial_handle *handle, mbus_frame *frame)
{
char buff[PACKET_BUFF_SIZE];
int len, remaining, nread;
bzero((void *)buff, sizeof(buff));
//
// read data until a packet is received
//
remaining = 1; // start by reading 1 byte
len = 0;
do {
//printf("%s: Attempt to read %d bytes [len = %d]\n", __PRETTY_FUNCTION__, remaining, len);
if ((nread = read(handle->fd, &buff[len], remaining)) == -1)
{
// fprintf(stderr, "%s: aborting recv frame (remaining = %d, len = %d, nread = %d)\n",
// __PRETTY_FUNCTION__, remaining, len, nread);
return -1;
}
// printf("%s: Got %d byte [remaining %d, len %d]\n", __PRETTY_FUNCTION__, nread, remaining, len);
len += nread;
} while ((remaining = mbus_parse(frame, buff, len)) > 0);
if(remaining < 0)
{
// Would be OK when e.g. scanning the bus, otherwise it is a failure.
// printf("%s: M-Bus layer failed to receive complete data.\n", __PRETTY_FUNCTION__);
return -1;
}
if (len == -1)
{
fprintf(stderr, "%s: M-Bus layer failed to parse data.\n", __PRETTY_FUNCTION__);
return -1;
}
return 0;
}