src/multimeter.c

   1 /**
   2  * collectd - src/multimeter.c
   3  * Copyright (C) 2005,2006  Peter Holik
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  18  *
  19  * Authors:
  20  *   Peter Holik <peter at holik.at>
  21  *
  22  * Used multimeter: Metex M-4650CR
  23  **/
  24
  25 #include "collectd.h"
  26 #include "common.h"
  27 #include "plugin.h"
  28
  29 #if HAVE_TERMIOS_H && HAVE_SYS_IOCTL_H && HAVE_MATH_H
  30 # include <termios.h>
  31 # include <sys/ioctl.h>
  32 # include <math.h>
  33 #else
  34 # error "No applicable input method."
  35 #endif
  36
  37 static int fd = -1;
  38
  39 #define LINE_LENGTH 14
  40 static int multimeter_read_value(double *value)
  41 {
  42         int retry = 3; /* sometimes we receive garbadge */
  43
  44         do
  45         {
  46                 struct timeval time_end;
  47
  48                 tcflush(fd, TCIFLUSH);
  49
  50                 if (gettimeofday (&time_end, NULL) < 0)
  51                 {
  52                         char errbuf[1024];
  53                         ERROR ("multimeter plugin: gettimeofday failed: %s",
  54                                         sstrerror (errno, errbuf,
  55                                                 sizeof (errbuf)));
  56                         return (-1);
  57                 }
  58                 time_end.tv_sec++;
  59
  60                 while (1)
  61                 {
  62                         char buf[LINE_LENGTH];
  63                         char *range;
  64                         int status;
  65                         fd_set rfds;
  66                         struct timeval timeout;
  67                         struct timeval time_now;
  68
  69                         status = swrite (fd, "D", 1);
  70                         if (status < 0)
  71                         {
  72                                 ERROR ("multimeter plugin: swrite failed.");
  73                                 return (-1);
  74                         }
  75
  76                         FD_ZERO(&rfds);
  77                         FD_SET(fd, &rfds);
  78
  79                         if (gettimeofday (&time_now, NULL) < 0)
  80                         {
  81                                 char errbuf[1024];
  82                                 ERROR ("multimeter plugin: "
  83                                                 "gettimeofday failed: %s",
  84                                                 sstrerror (errno, errbuf,
  85                                                         sizeof (errbuf)));
  86                                 return (-1);
  87                         }
  88                         if (timeval_cmp (time_end, time_now, &timeout) < 0)
  89                                 break;
  90
  91                         status = select(fd+1, &rfds, NULL, NULL, &timeout);
  92
  93                         if (status > 0) /* usually we succeed */
  94                         {
  95                                 status = read(fd, buf, LINE_LENGTH);
  96
  97                                 if ((status < 0) && ((errno == EAGAIN) || (errno == EINTR)))
  98                                         continue;
  99
 100                                 /* Format: "DC 00.000mV  \r" */
 101                                 if (status > 0 && status == LINE_LENGTH)
 102                                 {
 103                                         *value = strtod(buf + 2, &range);
 104
 105                                         if ( range > (buf + 6) )
 106                                         {
 107                                                 range = buf + 9;
 108
 109                                                 switch ( *range )
 110                                                 {
 111                                                         case 'p': *value *= 1.0E-12; break;
 112                                                         case 'n': *value *= 1.0E-9; break;
 113                                                         case 'u': *value *= 1.0E-6; break;
 114                                                         case 'm': *value *= 1.0E-3; break;
 115                                                         case 'k': *value *= 1.0E3; break;
 116                                                         case 'M': *value *= 1.0E6; break;
 117                                                         case 'G': *value *= 1.0E9; break;
 118                                                 }
 119                                         }
 120                                         else
 121                                                 return (-1); /* Overflow */
 122
 123                                         return (0); /* value received */
 124                                 }
 125                                 else break;
 126                         }
 127                         else if (!status) /* Timeout */
 128                         {
 129                                 break;
 130                         }
 131                         else if ((status == -1) && ((errno == EAGAIN) || (errno == EINTR)))
 132                         {
 133                                 continue;
 134                         }
 135                         else /* status == -1 */
 136                         {
 137                                 char errbuf[1024];
 138                                 ERROR ("multimeter plugin: "
 139                                                 "select failed: %s",
 140                                                 sstrerror (errno, errbuf, sizeof (errbuf)));
 141                                 break;
 142                         }
 143                 }
 144         } while (--retry);
 145
 146         return (-2);  /* no value received */
 147 } /* int multimeter_read_value */
 148
 149 static int multimeter_init (void)
 150 {
 151         int i;
 152         char device[] = "/dev/ttyS ";
 153
 154         for (i = 0; i < 10; i++)
 155         {
 156                 device[strlen(device)-1] = i + '0';
 157
 158                 if ((fd = open(device, O_RDWR | O_NOCTTY)) > 0)
 159                 {
 160                         struct termios tios;
 161                         int rts = TIOCM_RTS;
 162                         double value;
 163
 164                         tios.c_cflag = B1200 | CS7 | CSTOPB | CREAD | CLOCAL;
 165                         tios.c_iflag = IGNBRK | IGNPAR;
 166                         tios.c_oflag = 0;
 167                         tios.c_lflag = 0;
 168                         tios.c_cc[VTIME] = 3;
 169                         tios.c_cc[VMIN]  = LINE_LENGTH;
 170
 171                         tcflush(fd, TCIFLUSH);
 172                         tcsetattr(fd, TCSANOW, &tios);
 173                         ioctl(fd, TIOCMBIC, &rts);
 174
 175                         if (multimeter_read_value (&value) < -1)
 176                         {
 177                                 close (fd);
 178                                 fd = -1;
 179                         }
 180                         else
 181                         {
 182                                 INFO ("multimeter plugin: Device "
 183                                                 "found at %s", device);
 184                                 return (0);
 185                         }
 186                 }
 187         }
 188
 189         ERROR ("multimeter plugin: No device found");
 190         return (-1);
 191 }
 192 #undef LINE_LENGTH
 193
 194 static void multimeter_submit (double value)
 195 {
 196         value_t values[1];
 197         value_list_t vl = VALUE_LIST_INIT;
 198
 199         values[0].gauge = value;
 200
 201         vl.values = values;
 202         vl.values_len = 1;
 203         sstrncpy (vl.host, hostname_g, sizeof (vl.host));
 204         sstrncpy (vl.plugin, "multimeter", sizeof (vl.plugin));
 205         sstrncpy (vl.type, "multimeter", sizeof (vl.type));
 206
 207         plugin_dispatch_values (&vl);
 208 }
 209
 210 static int multimeter_read (void)
 211 {
 212         double value;
 213
 214         if (fd < 0)
 215                 return (-1);
 216
 217         if (multimeter_read_value (&value) != 0)
 218                 return (-1);
 219
 220         multimeter_submit (value);
 221         return (0);
 222 } /* int multimeter_read */
 223
 224 static int multimeter_shutdown (void)
 225 {
 226         if (fd >= 0)
 227         {
 228                 close (fd);
 229                 fd = -1;
 230         }
 231
 232         return (0);
 233 }
 234
 235 void module_register (void)
 236 {
 237         plugin_register_init ("multimeter", multimeter_init);
 238         plugin_register_read ("multimeter", multimeter_read);
 239         plugin_register_shutdown ("multimeter", multimeter_shutdown);
 240 } /* void module_register */