src/hardware/fluke-dmm/protocol.c

   1 /*
   2  * This file is part of the libsigrok project.
   3  *
   4  * Copyright (C) 2012 Bert Vermeulen <bert@biot.com>
   5  *
   6  * This program is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <stdlib.h>
  22 #include <math.h>
  23 #include <string.h>
  24 #include <glib.h>
  25 #include <libsigrok/libsigrok.h>
  26 #include "libsigrok-internal.h"
  27 #include "protocol.h"
  28
  29 static int count_digits(const char *str)
  30 {
  31         int digits;
  32
  33         if (*str == '-' || *str == '+')
  34                 str++;
  35
  36         while (*str >= '0' && *str <= '9')
  37                 str++;
  38
  39         digits = 0;
  40         if (*str == '.') {
  41                 str++;
  42                 while (*str >= '0' && *str <= '9') {
  43                         str++;
  44                         digits++;
  45                 }
  46         }
  47
  48         return digits;
  49 }
  50
  51 static void handle_qm_18x(const struct sr_dev_inst *sdi, char **tokens)
  52 {
  53         struct dev_context *devc;
  54         struct sr_datafeed_packet packet;
  55         struct sr_datafeed_analog analog;
  56         struct sr_analog_encoding encoding;
  57         struct sr_analog_meaning meaning;
  58         struct sr_analog_spec spec;
  59         float fvalue;
  60         char *e, *u;
  61         gboolean is_oor;
  62         int digits;
  63         int exponent;
  64         enum sr_mq mq;
  65         enum sr_unit unit;
  66         enum sr_mqflag mqflags;
  67
  68         devc = sdi->priv;
  69
  70         if (strcmp(tokens[0], "QM") || !tokens[1])
  71                 return;
  72
  73         if ((e = strstr(tokens[1], "Out of range"))) {
  74                 is_oor = TRUE;
  75                 fvalue = -1;
  76                 digits = 0;
  77                 while (*e && *e != '.')
  78                         e++;
  79         } else {
  80                 is_oor = FALSE;
  81                 /* Delimit the float, since sr_atof_ascii() wants only
  82                  * a valid float here. */
  83                 e = tokens[1];
  84                 while (*e && *e != ' ')
  85                         e++;
  86                 *e++ = '\0';
  87                 if (sr_atof_ascii(tokens[1], &fvalue) != SR_OK) {
  88                         /* Happens all the time, when switching modes. */
  89                         sr_dbg("Invalid float: '%s'", tokens[1]);
  90                         return;
  91                 }
  92                 digits = count_digits(tokens[1]);
  93         }
  94         while (*e && *e == ' ')
  95                 e++;
  96
  97         if (is_oor)
  98                 fvalue = NAN;
  99
 100         mq = 0;
 101         unit = 0;
 102         exponent = 0;
 103         mqflags = 0;
 104         if ((u = strstr(e, "V DC")) || (u = strstr(e, "V AC"))) {
 105                 mq = SR_MQ_VOLTAGE;
 106                 unit = SR_UNIT_VOLT;
 107                 if (!is_oor && e[0] == 'm')
 108                         exponent = -3;
 109                 /* This catches "V AC", "V DC" and "V AC+DC". */
 110                 if (strstr(u, "AC"))
 111                         mqflags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
 112                 if (strstr(u, "DC"))
 113                         mqflags |= SR_MQFLAG_DC;
 114         } else if ((u = strstr(e, "dBV")) || (u = strstr(e, "dBm"))) {
 115                 mq = SR_MQ_VOLTAGE;
 116                 if (u[2] == 'm')
 117                         unit = SR_UNIT_DECIBEL_MW;
 118                 else
 119                         unit = SR_UNIT_DECIBEL_VOLT;
 120                 mqflags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
 121         } else if ((u = strstr(e, "Ohms"))) {
 122                 mq = SR_MQ_RESISTANCE;
 123                 unit = SR_UNIT_OHM;
 124                 if (is_oor)
 125                         fvalue = INFINITY;
 126                 else if (e[0] == 'k')
 127                         exponent = 3;
 128                 else if (e[0] == 'M')
 129                         exponent = 6;
 130         } else if (!strcmp(e, "nS")) {
 131                 mq = SR_MQ_CONDUCTANCE;
 132                 unit = SR_UNIT_SIEMENS;
 133                 exponent = -9;
 134         } else if ((u = strstr(e, "Farads"))) {
 135                 mq = SR_MQ_CAPACITANCE;
 136                 unit = SR_UNIT_FARAD;
 137                 if (!is_oor) {
 138                         if (e[0] == 'm')
 139                                 exponent = -3;
 140                         else if (e[0] == 'u')
 141                                 exponent = -6;
 142                         else if (e[0] == 'n')
 143                                 exponent = -9;
 144                 }
 145         } else if ((u = strstr(e, "Deg C")) || (u = strstr(e, "Deg F"))) {
 146                 mq = SR_MQ_TEMPERATURE;
 147                 if (u[4] == 'C')
 148                         unit = SR_UNIT_CELSIUS;
 149                 else
 150                         unit = SR_UNIT_FAHRENHEIT;
 151         } else if ((u = strstr(e, "A AC")) || (u = strstr(e, "A DC"))) {
 152                 mq = SR_MQ_CURRENT;
 153                 unit = SR_UNIT_AMPERE;
 154                 /* This catches "A AC", "A DC" and "A AC+DC". */
 155                 if (strstr(u, "AC"))
 156                         mqflags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
 157                 if (strstr(u, "DC"))
 158                         mqflags |= SR_MQFLAG_DC;
 159                 if (!is_oor) {
 160                         if (e[0] == 'm')
 161                                 exponent = -3;
 162                         else if (e[0] == 'u')
 163                                 exponent = -6;
 164                 }
 165         } else if ((u = strstr(e, "Hz"))) {
 166                 mq = SR_MQ_FREQUENCY;
 167                 unit = SR_UNIT_HERTZ;
 168                 if (e[0] == 'k')
 169                         exponent = 3;
 170         } else if (!strcmp(e, "%")) {
 171                 mq = SR_MQ_DUTY_CYCLE;
 172                 unit = SR_UNIT_PERCENTAGE;
 173         } else if ((u = strstr(e, "ms"))) {
 174                 mq = SR_MQ_PULSE_WIDTH;
 175                 unit = SR_UNIT_SECOND;
 176                 exponent = -3;
 177         }
 178
 179         if (mq != 0) {
 180                 /* Got a measurement. */
 181                 digits -= exponent;
 182                 fvalue *= pow(10.0f, exponent);
 183
 184                 sr_analog_init(&analog, &encoding, &meaning, &spec, digits);
 185                 analog.data = &fvalue;
 186                 analog.num_samples = 1;
 187                 analog.meaning->unit = unit;
 188                 analog.meaning->mq = mq;
 189                 analog.meaning->mqflags = mqflags;
 190                 analog.meaning->channels = sdi->channels;
 191
 192                 packet.type = SR_DF_ANALOG;
 193                 packet.payload = &analog;
 194                 sr_session_send(sdi, &packet);
 195                 sr_sw_limits_update_samples_read(&devc->limits, 1);
 196         }
 197 }
 198
 199 static void handle_qm_28x(const struct sr_dev_inst *sdi, char **tokens)
 200 {
 201         struct dev_context *devc;
 202         struct sr_datafeed_packet packet;
 203         struct sr_datafeed_analog analog;
 204         struct sr_analog_encoding encoding;
 205         struct sr_analog_meaning meaning;
 206         struct sr_analog_spec spec;
 207         float fvalue;
 208         int digits;
 209
 210         devc = sdi->priv;
 211
 212         if (!tokens[1])
 213                 return;
 214
 215         if (sr_atof_ascii(tokens[0], &fvalue) != SR_OK) {
 216                 sr_err("Invalid float '%s'.", tokens[0]);
 217                 return;
 218         }
 219         digits = count_digits(tokens[0]);
 220
 221         sr_analog_init(&analog, &encoding, &meaning, &spec, digits);
 222         analog.data = &fvalue;
 223         analog.meaning->channels = sdi->channels;
 224         analog.num_samples = 1;
 225         analog.meaning->mq = 0;
 226
 227         if (!strcmp(tokens[1], "VAC") || !strcmp(tokens[1], "VDC")) {
 228                 analog.meaning->mq = SR_MQ_VOLTAGE;
 229                 analog.meaning->unit = SR_UNIT_VOLT;
 230                 if (!strcmp(tokens[2], "NORMAL")) {
 231                         if (tokens[1][1] == 'A') {
 232                                 analog.meaning->mqflags |= SR_MQFLAG_AC;
 233                                 analog.meaning->mqflags |= SR_MQFLAG_RMS;
 234                         } else
 235                                 analog.meaning->mqflags |= SR_MQFLAG_DC;
 236                 } else if (!strcmp(tokens[2], "OL") || !strcmp(tokens[2], "OL_MINUS")) {
 237                         fvalue = NAN;
 238                 } else
 239                         analog.meaning->mq = 0;
 240         } else if (!strcmp(tokens[1], "dBV") || !strcmp(tokens[1], "dBm")) {
 241                 analog.meaning->mq = SR_MQ_VOLTAGE;
 242                 if (tokens[1][2] == 'm')
 243                         analog.meaning->unit = SR_UNIT_DECIBEL_MW;
 244                 else
 245                         analog.meaning->unit = SR_UNIT_DECIBEL_VOLT;
 246                 analog.meaning->mqflags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
 247         } else if (!strcmp(tokens[1], "CEL") || !strcmp(tokens[1], "FAR")) {
 248                 if (!strcmp(tokens[2], "NORMAL")) {
 249                         analog.meaning->mq = SR_MQ_TEMPERATURE;
 250                         if (tokens[1][0] == 'C')
 251                                 analog.meaning->unit = SR_UNIT_CELSIUS;
 252                         else
 253                                 analog.meaning->unit = SR_UNIT_FAHRENHEIT;
 254                 }
 255         } else if (!strcmp(tokens[1], "OHM")) {
 256                 if (!strcmp(tokens[3], "NONE")) {
 257                         analog.meaning->mq = SR_MQ_RESISTANCE;
 258                         analog.meaning->unit = SR_UNIT_OHM;
 259                         if (!strcmp(tokens[2], "OL") || !strcmp(tokens[2], "OL_MINUS")) {
 260                                 fvalue = INFINITY;
 261                         } else if (strcmp(tokens[2], "NORMAL"))
 262                                 analog.meaning->mq = 0;
 263                 } else if (!strcmp(tokens[3], "OPEN_CIRCUIT")) {
 264                         analog.meaning->mq = SR_MQ_CONTINUITY;
 265                         analog.meaning->unit = SR_UNIT_BOOLEAN;
 266                         fvalue = 0.0;
 267                 } else if (!strcmp(tokens[3], "SHORT_CIRCUIT")) {
 268                         analog.meaning->mq = SR_MQ_CONTINUITY;
 269                         analog.meaning->unit = SR_UNIT_BOOLEAN;
 270                         fvalue = 1.0;
 271                 }
 272         } else if (!strcmp(tokens[1], "F")
 273                         && !strcmp(tokens[2], "NORMAL")
 274                         && !strcmp(tokens[3], "NONE")) {
 275                 analog.meaning->mq = SR_MQ_CAPACITANCE;
 276                 analog.meaning->unit = SR_UNIT_FARAD;
 277         } else if (!strcmp(tokens[1], "AAC") || !strcmp(tokens[1], "ADC")) {
 278                 analog.meaning->mq = SR_MQ_CURRENT;
 279                 analog.meaning->unit = SR_UNIT_AMPERE;
 280                 if (!strcmp(tokens[2], "NORMAL")) {
 281                         if (tokens[1][1] == 'A') {
 282                                 analog.meaning->mqflags |= SR_MQFLAG_AC;
 283                                 analog.meaning->mqflags |= SR_MQFLAG_RMS;
 284                         } else
 285                                 analog.meaning->mqflags |= SR_MQFLAG_DC;
 286                 } else if (!strcmp(tokens[2], "OL") || !strcmp(tokens[2], "OL_MINUS")) {
 287                         fvalue = NAN;
 288                 } else
 289                         analog.meaning->mq = 0;
 290         } else if (!strcmp(tokens[1], "Hz") && !strcmp(tokens[2], "NORMAL")) {
 291                 analog.meaning->mq = SR_MQ_FREQUENCY;
 292                 analog.meaning->unit = SR_UNIT_HERTZ;
 293         } else if (!strcmp(tokens[1], "PCT") && !strcmp(tokens[2], "NORMAL")) {
 294                 analog.meaning->mq = SR_MQ_DUTY_CYCLE;
 295                 analog.meaning->unit = SR_UNIT_PERCENTAGE;
 296         } else if (!strcmp(tokens[1], "S") && !strcmp(tokens[2], "NORMAL")) {
 297                 analog.meaning->mq = SR_MQ_PULSE_WIDTH;
 298                 analog.meaning->unit = SR_UNIT_SECOND;
 299         } else if (!strcmp(tokens[1], "SIE") && !strcmp(tokens[2], "NORMAL")) {
 300                 analog.meaning->mq = SR_MQ_CONDUCTANCE;
 301                 analog.meaning->unit = SR_UNIT_SIEMENS;
 302         }
 303
 304         if (analog.meaning->mq != 0) {
 305                 /* Got a measurement. */
 306                 packet.type = SR_DF_ANALOG;
 307                 packet.payload = &analog;
 308                 sr_session_send(sdi, &packet);
 309                 sr_sw_limits_update_samples_read(&devc->limits, 1);
 310         }
 311 }
 312
 313 static void handle_qm_19x_meta(const struct sr_dev_inst *sdi, char **tokens)
 314 {
 315         struct dev_context *devc;
 316         int meas_type, meas_unit, meas_char, i;
 317
 318         /* Make sure we have 7 valid tokens. */
 319         for (i = 0; tokens[i] && i < 7; i++);
 320         if (i != 7)
 321                 return;
 322
 323         if (strcmp(tokens[1], "1"))
 324                 /* Invalid measurement. */
 325                 return;
 326
 327         if (strcmp(tokens[2], "3"))
 328                 /* Only interested in input from the meter mode source. */
 329                 return;
 330
 331         devc = sdi->priv;
 332
 333         /* Measurement type 11 == absolute, 19 = relative */
 334         meas_type = strtol(tokens[0], NULL, 10);
 335         if (meas_type != 11 && meas_type != 19)
 336                 /* Device is in some mode we don't support. */
 337                 return;
 338
 339         /* We might get metadata for absolute and relative mode (if the device
 340          * is in relative mode). In that case, relative takes precedence. */
 341         if (meas_type == 11 && devc->meas_type == 19)
 342                 return;
 343
 344         meas_unit = strtol(tokens[3], NULL, 10);
 345         if (meas_unit == 0)
 346                 /* Device is turned off. Really. */
 347                 return;
 348         meas_char = strtol(tokens[4], NULL, 10);
 349
 350         devc->mq = 0;
 351         devc->unit = 0;
 352         devc->mqflags = 0;
 353
 354         switch (meas_unit) {
 355         case 1:
 356                 devc->mq = SR_MQ_VOLTAGE;
 357                 devc->unit = SR_UNIT_VOLT;
 358                 if (meas_char == 1)
 359                         devc->mqflags |= SR_MQFLAG_DC;
 360                 else if (meas_char == 2)
 361                         devc->mqflags |= SR_MQFLAG_AC;
 362                 else if (meas_char == 3)
 363                         devc->mqflags |= SR_MQFLAG_DC | SR_MQFLAG_AC;
 364                 else if (meas_char == 15)
 365                         devc->mqflags |= SR_MQFLAG_DIODE | SR_MQFLAG_DC;
 366                 break;
 367         case 2:
 368                 devc->mq = SR_MQ_CURRENT;
 369                 devc->unit = SR_UNIT_AMPERE;
 370                 if (meas_char == 1)
 371                         devc->mqflags |= SR_MQFLAG_DC;
 372                 else if (meas_char == 2)
 373                         devc->mqflags |= SR_MQFLAG_AC;
 374                 else if (meas_char == 3)
 375                         devc->mqflags |= SR_MQFLAG_DC | SR_MQFLAG_AC;
 376                 break;
 377         case 3:
 378                 if (meas_char == 1) {
 379                         devc->mq = SR_MQ_RESISTANCE;
 380                         devc->unit = SR_UNIT_OHM;
 381                 } else if (meas_char == 16) {
 382                         devc->mq = SR_MQ_CONTINUITY;
 383                         devc->unit = SR_UNIT_BOOLEAN;
 384                 }
 385                 break;
 386         case 12:
 387                 devc->mq = SR_MQ_TEMPERATURE;
 388                 devc->unit = SR_UNIT_CELSIUS;
 389                 break;
 390         case 13:
 391                 devc->mq = SR_MQ_TEMPERATURE;
 392                 devc->unit = SR_UNIT_FAHRENHEIT;
 393                 break;
 394         default:
 395                 sr_dbg("unknown unit: %d", meas_unit);
 396         }
 397         if (devc->mq == 0 && devc->unit == 0)
 398                 return;
 399
 400         /* If we got here, we know how to interpret the measurement. */
 401         devc->meas_type = meas_type;
 402         if (meas_type == 11)
 403                 /* Absolute meter reading. */
 404                 devc->is_relative = FALSE;
 405         else if (!strcmp(tokens[0], "19"))
 406                 /* Relative meter reading. */
 407                 devc->is_relative = TRUE;
 408
 409 }
 410
 411 static void handle_qm_19x_data(const struct sr_dev_inst *sdi, char **tokens)
 412 {
 413         struct dev_context *devc;
 414         struct sr_datafeed_packet packet;
 415         struct sr_datafeed_analog analog;
 416         struct sr_analog_encoding encoding;
 417         struct sr_analog_meaning meaning;
 418         struct sr_analog_spec spec;
 419         float fvalue;
 420         int digits;
 421
 422         digits = 2;
 423         if (!strcmp(tokens[0], "9.9E+37")) {
 424                 /* An invalid measurement shows up on the display as "OL", but
 425                  * comes through like this. Since comparing 38-digit floats
 426                  * is rather problematic, we'll cut through this here. */
 427                 fvalue = NAN;
 428         } else {
 429                 if (sr_atof_ascii(tokens[0], &fvalue) != SR_OK || fvalue == 0.0) {
 430                         sr_err("Invalid float '%s'.", tokens[0]);
 431                         return;
 432                 }
 433                 digits = count_digits(tokens[0]);
 434         }
 435
 436         devc = sdi->priv;
 437         if (devc->mq == 0 || devc->unit == 0)
 438                 /* Don't have valid metadata yet. */
 439                 return;
 440
 441         if (devc->mq == SR_MQ_RESISTANCE && isnan(fvalue))
 442                 fvalue = INFINITY;
 443         else if (devc->mq == SR_MQ_CONTINUITY) {
 444                 if (isnan(fvalue))
 445                         fvalue = 0.0;
 446                 else
 447                         fvalue = 1.0;
 448         }
 449
 450         sr_analog_init(&analog, &encoding, &meaning, &spec, digits);
 451         analog.meaning->channels = sdi->channels;
 452         analog.num_samples = 1;
 453         analog.data = &fvalue;
 454         analog.meaning->mq = devc->mq;
 455         analog.meaning->unit = devc->unit;
 456         analog.meaning->mqflags = 0;
 457         packet.type = SR_DF_ANALOG;
 458         packet.payload = &analog;
 459         sr_session_send(sdi, &packet);
 460
 461         sr_sw_limits_update_samples_read(&devc->limits, 1);
 462 }
 463
 464 static void handle_line(const struct sr_dev_inst *sdi)
 465 {
 466         struct dev_context *devc;
 467         struct sr_serial_dev_inst *serial;
 468         int num_tokens, n, i;
 469         char cmd[16], **tokens;
 470         int ret;
 471
 472         devc = sdi->priv;
 473         serial = sdi->conn;
 474         sr_spew("Received line '%s' (%d).", devc->buf, devc->buflen);
 475
 476         if (devc->buflen == 1) {
 477                 if (devc->buf[0] != '0') {
 478                         /* Not just a CMD_ACK from the query command. */
 479                         sr_dbg("Got CMD_ACK '%c'.", devc->buf[0]);
 480                         devc->expect_response = FALSE;
 481                 }
 482                 devc->buflen = 0;
 483                 return;
 484         }
 485
 486         tokens = g_strsplit(devc->buf, ",", 0);
 487         if (tokens[0]) {
 488                 switch (devc->profile->model) {
 489                 case FLUKE_87:
 490                 case FLUKE_89:
 491                 case FLUKE_187:
 492                 case FLUKE_189:
 493                         devc->expect_response = FALSE;
 494                         handle_qm_18x(sdi, tokens);
 495                         break;
 496                 case FLUKE_190:
 497                         devc->expect_response = FALSE;
 498                         num_tokens = g_strv_length(tokens);
 499                         if (num_tokens < 7) {
 500                                 /* Response to QM <n> measurement request. */
 501                                 handle_qm_19x_data(sdi, tokens);
 502                                 break;
 503                         }
 504                         /*
 505                          * Response to QM: This is a comma-separated list of
 506                          * fields with metadata about the measurement. This
 507                          * format can return multiple sets of metadata,
 508                          * split into sets of 7 tokens each.
 509                          */
 510                         devc->meas_type = 0;
 511                         for (i = 0; i < num_tokens; i += 7)
 512                                 handle_qm_19x_meta(sdi, tokens + i);
 513                         if (devc->meas_type) {
 514                                 /*
 515                                  * Slip the request in now, before the main
 516                                  * timer loop asks for metadata again.
 517                                  */
 518                                 n = sprintf(cmd, "QM %d\r", devc->meas_type);
 519                                 ret = serial_write_blocking(serial,
 520                                         cmd, n, SERIAL_WRITE_TIMEOUT_MS);
 521                                 if (ret < 0)
 522                                         sr_err("Cannot send QM (measurement).");
 523                         }
 524                         break;
 525                 case FLUKE_287:
 526                 case FLUKE_289:
 527                         devc->expect_response = FALSE;
 528                         handle_qm_28x(sdi, tokens);
 529                         break;
 530                 }
 531         }
 532         g_strfreev(tokens);
 533         devc->buflen = 0;
 534 }
 535
 536 SR_PRIV int fluke_receive_data(int fd, int revents, void *cb_data)
 537 {
 538         struct sr_dev_inst *sdi;
 539         struct dev_context *devc;
 540         struct sr_serial_dev_inst *serial;
 541         int len;
 542         int64_t now, elapsed;
 543
 544         (void)fd;
 545
 546         if (!(sdi = cb_data))
 547                 return TRUE;
 548
 549         if (!(devc = sdi->priv))
 550                 return TRUE;
 551
 552         serial = sdi->conn;
 553         if (revents == G_IO_IN) {
 554                 /* Serial data arrived. */
 555                 while (FLUKEDMM_BUFSIZE - devc->buflen - 1 > 0) {
 556                         len = serial_read_nonblocking(serial, devc->buf + devc->buflen, 1);
 557                         if (len < 1)
 558                                 break;
 559                         devc->buflen++;
 560                         *(devc->buf + devc->buflen) = '\0';
 561                         if (*(devc->buf + devc->buflen - 1) == '\r') {
 562                                 *(devc->buf + --devc->buflen) = '\0';
 563                                 handle_line(sdi);
 564                                 break;
 565                         }
 566                 }
 567         }
 568
 569         if (sr_sw_limits_check(&devc->limits)) {
 570                 sr_dev_acquisition_stop(sdi);
 571                 return TRUE;
 572         }
 573
 574         now = g_get_monotonic_time() / 1000;
 575         elapsed = now - devc->cmd_sent_at;
 576         /* Send query command at poll_period interval, or after 1 second
 577          * has elapsed. This will make it easier to recover from any
 578          * out-of-sync or temporary disconnect issues. */
 579         if ((devc->expect_response == FALSE && elapsed > devc->profile->poll_period)
 580                         || elapsed > devc->profile->timeout) {
 581                 if (serial_write_blocking(serial, "QM\r", 3, SERIAL_WRITE_TIMEOUT_MS) < 0)
 582                         sr_err("Unable to send QM.");
 583                 devc->cmd_sent_at = now;
 584                 devc->expect_response = TRUE;
 585         }
 586
 587         return TRUE;
 588 }