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
  27 #include "common.h"
  28 #include "plugin.h"
  29
  30 #if HAVE_TERMIOS_H && HAVE_SYS_IOCTL_H && HAVE_MATH_H
  31 # include <termios.h>
  32 # include <sys/ioctl.h>
  33 # include <math.h>
  34 #else
  35 # error "No applicable input method."
  36 #endif
  37
  38 static int fd = -1;
  39
  40 #define LINE_LENGTH 14
  41 static int multimeter_read_value(double *value)
  42 {
  43         int retry = 3; /* sometimes we receive garbadge */
  44
  45         do
  46         {
  47                 struct timeval time_end;
  48
  49                 tcflush(fd, TCIFLUSH);
  50
  51                 if (gettimeofday (&time_end, NULL) < 0)
  52                 {
  53                         char errbuf[1024];
  54                         ERROR ("multimeter plugin: gettimeofday failed: %s",
  55                                         sstrerror (errno, errbuf,
  56                                                 sizeof (errbuf)));
  57                         return (-1);
  58                 }
  59                 time_end.tv_sec++;
  60
  61                 while (1)
  62                 {
  63                         char buf[LINE_LENGTH];
  64                         char *range;
  65                         int status;
  66                         fd_set rfds;
  67                         struct timeval timeout;
  68                         struct timeval time_now;
  69
  70                         status = swrite (fd, "D", 1);
  71                         if (status < 0)
  72                         {
  73                                 ERROR ("multimeter plugin: swrite failed.");
  74                                 return (-1);
  75                         }
  76
  77                         FD_ZERO(&rfds);
  78                         FD_SET(fd, &rfds);
  79
  80                         if (gettimeofday (&time_now, NULL) < 0)
  81                         {
  82                                 char errbuf[1024];
  83                                 ERROR ("multimeter plugin: "
  84                                                 "gettimeofday failed: %s",
  85                                                 sstrerror (errno, errbuf,
  86                                                         sizeof (errbuf)));
  87                                 return (-1);
  88                         }
  89                         if (timeval_cmp (time_end, time_now, &timeout) < 0)
  90                                 break;
  91
  92                         status = select(fd+1, &rfds, NULL, NULL, &timeout);
  93
  94                         if (status > 0) /* usually we succeed */
  95                         {
  96                                 status = read(fd, buf, LINE_LENGTH);
  97
  98                                 if ((status < 0) && ((errno == EAGAIN) || (errno == EINTR)))
  99                                         continue;
 100
 101                                 /* Format: "DC 00.000mV  \r" */
 102                                 if (status > 0 && status == LINE_LENGTH)
 103                                 {
 104                                         *value = strtod(buf + 2, &range);
 105
 106                                         if ( range > (buf + 6) )
 107                                         {
 108                                                 range = buf + 9;
 109
 110                                                 switch ( *range )
 111                                                 {
 112                                                         case 'p': *value *= 1.0E-12; break;
 113                                                         case 'n': *value *= 1.0E-9; break;
 114                                                         case 'u': *value *= 1.0E-6; break;
 115                                                         case 'm': *value *= 1.0E-3; break;
 116                                                         case 'k': *value *= 1.0E3; break;
 117                                                         case 'M': *value *= 1.0E6; break;
 118                                                         case 'G': *value *= 1.0E9; break;
 119                                                 }
 120                                         }
 121                                         else
 122                                                 return (-1); /* Overflow */
 123
 124                                         return (0); /* value received */
 125                                 }
 126                                 else break;
 127                         }
 128                         else if (!status) /* Timeout */
 129                         {
 130                                 break;
 131                         }
 132                         else if ((status == -1) && ((errno == EAGAIN) || (errno == EINTR)))
 133                         {
 134                                 continue;
 135                         }
 136                         else /* status == -1 */
 137                         {
 138                                 char errbuf[1024];
 139                                 ERROR ("multimeter plugin: "
 140                                                 "select failed: %s",
 141                                                 sstrerror (errno, errbuf, sizeof (errbuf)));
 142                                 break;
 143                         }
 144                 }
 145         } while (--retry);
 146
 147         return (-2);  /* no value received */
 148 } /* int multimeter_read_value */
 149
 150 static int multimeter_init (void)
 151 {
 152         char device[] = "/dev/ttyS ";
 153
 154         for (int i = 0; i < 10; i++)
 155         {
 156                 device[strlen(device)-1] = i + '0';
 157
 158                 if ((fd = open(device, O_RDWR | O_NOCTTY)) != -1)
 159                 {
 160                         struct termios tios = { 0 };
 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_list_t vl = VALUE_LIST_INIT;
 197
 198         vl.values = &(value_t) { .gauge = value };
 199         vl.values_len = 1;
 200         sstrncpy (vl.plugin, "multimeter", sizeof (vl.plugin));
 201         sstrncpy (vl.type, "multimeter", sizeof (vl.type));
 202
 203         plugin_dispatch_values (&vl);
 204 }
 205
 206 static int multimeter_read (void)
 207 {
 208         double value;
 209
 210         if (fd < 0)
 211                 return (-1);
 212
 213         if (multimeter_read_value (&value) != 0)
 214                 return (-1);
 215
 216         multimeter_submit (value);
 217         return (0);
 218 } /* int multimeter_read */
 219
 220 static int multimeter_shutdown (void)
 221 {
 222         if (fd >= 0)
 223         {
 224                 close (fd);
 225                 fd = -1;
 226         }
 227
 228         return (0);
 229 }
 230
 231 void module_register (void)
 232 {
 233         plugin_register_init ("multimeter", multimeter_init);
 234         plugin_register_read ("multimeter", multimeter_read);
 235         plugin_register_shutdown ("multimeter", multimeter_shutdown);
 236 } /* void module_register */