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
  26 #include <termios.h>
  27 #include <sys/ioctl.h>
  28 #include <math.h>
  29 #include "collectd.h"
  30 #include "common.h"
  31 #include "plugin.h"
  32
  33 #define MODULE_NAME "multimeter"
  34
  35 static char *multimeter_file = "multimeter.rrd";
  36
  37 static char *ds_def[] =
  38 {
  39         "DS:value:GAUGE:"COLLECTD_HEARTBEAT":U:U",
  40         NULL
  41 };
  42 static int ds_num = 1;
  43
  44 static int fd = -1;
  45
  46 static int multimeter_timeval_sub (struct timeval *tv1, struct timeval *tv2,
  47                 struct timeval *res)
  48 {
  49         if ((tv1->tv_sec < tv2->tv_sec) ||
  50             ((tv1->tv_sec == tv2->tv_sec) && (tv1->tv_usec < tv2->tv_usec)))
  51                 return (-1);
  52
  53         res->tv_sec  = tv1->tv_sec  - tv2->tv_sec;
  54         res->tv_usec = tv1->tv_usec - tv2->tv_usec;
  55
  56         assert ((res->tv_sec > 0) || ((res->tv_sec == 0) && (res->tv_usec > 0)));
  57
  58         while (res->tv_usec < 0)
  59         {
  60                 res->tv_usec += 1000000;
  61                 res->tv_sec--;
  62         }
  63         return (0);
  64 }
  65 #define LINE_LENGTH 14
  66 static int multimeter_read_value(double *value)
  67 {
  68         int retry = 3; /* sometimes we receive garbadge */
  69
  70         do
  71         {
  72                 struct timeval time_end;
  73
  74                 tcflush(fd, TCIFLUSH);
  75
  76                 if (gettimeofday (&time_end, NULL) < 0)
  77                 {
  78                         syslog (LOG_ERR, MODULE_NAME": gettimeofday failed: %s",
  79                                 strerror (errno));
  80                         return (-1);
  81                 }
  82                 time_end.tv_sec++;
  83
  84                 while (1)
  85                 {
  86                         char buf[LINE_LENGTH];
  87                         char *range;
  88                         int status;
  89                         fd_set rfds;
  90                         struct timeval timeout;
  91                         struct timeval time_now;
  92
  93                         write(fd, "D", 1);
  94
  95                         FD_ZERO(&rfds);
  96                         FD_SET(fd, &rfds);
  97
  98                         if (gettimeofday (&time_now, NULL) < 0)
  99                         {
 100                                 syslog (LOG_ERR, MODULE_NAME": gettimeofday failed: %s",
 101                                         strerror (errno));
 102                                 return (-1);
 103                         }
 104                         if (multimeter_timeval_sub (&time_end, &time_now, &timeout) == -1)
 105                                 break;
 106
 107                         status = select(fd+1, &rfds, NULL, NULL, &timeout);
 108
 109                         if (status > 0) /* usually we succeed */
 110                         {
 111                                 status = read(fd, buf, LINE_LENGTH);
 112
 113                                 if ((status < 0) && ((errno == EAGAIN) || (errno == EINTR)))
 114                                         continue;
 115
 116                                 /* Format: "DC 00.000mV  \r" */
 117                                 if (status > 0 && status == LINE_LENGTH)
 118                                 {
 119                                         *value = strtod(buf + 2, &range);
 120
 121                                         if ( range > (buf + 6) )
 122                                         {
 123                                                 range = buf + 9;
 124
 125                                                 switch ( *range )
 126                                                 {
 127                                                         case 'p': *value *= 1.0E-12; break;
 128                                                         case 'n': *value *= 1.0E-9; break;
 129                                                         case 'u': *value *= 1.0E-6; break;
 130                                                         case 'm': *value *= 1.0E-3; break;
 131                                                         case 'k': *value *= 1.0E3; break;
 132                                                         case 'M': *value *= 1.0E6; break;
 133                                                         case 'G': *value *= 1.0E9; break;
 134                                                 }
 135                                         }
 136                                         else
 137                                                 return (-1); /* Overflow */
 138
 139                                         return (0); /* value received */
 140                                 }
 141                                 else break;
 142                         }
 143                         else if (!status) /* Timeout */
 144                         {
 145                                 break;
 146                         }
 147                         else if ((status == -1) && ((errno == EAGAIN) || (errno == EINTR)))
 148                         {
 149                                 continue;
 150                         }
 151                         else /* status == -1 */
 152                         {
 153                                 syslog (LOG_ERR, MODULE_NAME": select failed: %s",
 154                                         strerror (errno));
 155                                 break;
 156                         }
 157                 }
 158         } while (--retry);
 159
 160         return (-2);  /* no value received */
 161 }
 162
 163 static void multimeter_init (void)
 164 {
 165         int i;
 166         char device[] = "/dev/ttyS ";
 167
 168         for (i = 0; i < 10; i++)
 169         {
 170                 device[strlen(device)-1] = i + '0';
 171
 172                 if ((fd = open(device, O_RDWR | O_NOCTTY)) > 0)
 173                 {
 174                         struct termios tios;
 175                         int rts = TIOCM_RTS;
 176                         double value;
 177
 178                         tios.c_cflag = B1200 | CS7 | CSTOPB | CREAD | CLOCAL;
 179                         tios.c_iflag = IGNBRK | IGNPAR;
 180                         tios.c_oflag = 0;
 181                         tios.c_lflag = 0;
 182                         tios.c_cc[VTIME] = 3;
 183                         tios.c_cc[VMIN]  = LINE_LENGTH;
 184
 185                         tcflush(fd, TCIFLUSH);
 186                         tcsetattr(fd, TCSANOW, &tios);
 187                         ioctl(fd, TIOCMBIC, &rts);
 188
 189                         if (multimeter_read_value(&value) < -1)
 190                         {
 191                                 close(fd);
 192                                 fd = -1;
 193                         }
 194                         else
 195                         {
 196                                 syslog (LOG_INFO, MODULE_NAME" found (%s)", device);
 197                                 return;
 198                         }
 199                 }
 200         }
 201         syslog (LOG_ERR, MODULE_NAME" not found");
 202 }
 203 #undef LINE_LENGTH
 204
 205 static void multimeter_write (char *host, char *inst, char *val)
 206 {
 207         rrd_update_file (host, multimeter_file, val, ds_def, ds_num);
 208 }
 209 #define BUFSIZE 128
 210 static void multimeter_submit (double *value)
 211 {
 212         char buf[BUFSIZE];
 213
 214         if (snprintf (buf, BUFSIZE, "%u:%f", (unsigned int) curtime, *value) >= BUFSIZE)
 215                 return;
 216
 217         plugin_submit (MODULE_NAME, NULL, buf);
 218 }
 219 #undef BUFSIZE
 220
 221 static void multimeter_read (void)
 222 {
 223         double value;
 224
 225         if (fd > -1 && !(multimeter_read_value(&value)))
 226                 multimeter_submit (&value);
 227 }
 228
 229 void module_register (void)
 230 {
 231         plugin_register (MODULE_NAME, multimeter_init, multimeter_read, multimeter_write);
 232 }
 233
 234 #undef MODULE_NAME