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         int exponent;
 210         char *e;
 211
 212         devc = sdi->priv;
 213
 214         if (!tokens[1])
 215                 return;
 216
 217         /* Split measurement into mantissa / exponent */
 218         e = tokens[0];
 219         while (*e) {
 220                 if (*e == 'e' || *e == 'E') {
 221                         *e = '\0';
 222                         e++;
 223                         break;
 224                 }
 225                 e++;
 226         }
 227
 228         if (sr_atof_ascii(tokens[0], &fvalue) != SR_OK) {
 229                 sr_err("Invalid mantissa '%s'.", tokens[0]);
 230                 return;
 231         }
 232
 233         if (sr_atoi(e, &exponent) != SR_OK) {
 234                 sr_err("Invalid exponent '%s'.", e);
 235                 return;
 236         }
 237
 238         digits = count_digits(tokens[0]) - exponent;
 239         fvalue *= pow(10.0f, exponent);
 240
 241         sr_analog_init(&analog, &encoding, &meaning, &spec, digits);
 242         analog.data = &fvalue;
 243         analog.meaning->channels = sdi->channels;
 244         analog.num_samples = 1;
 245         analog.meaning->mq = 0;
 246
 247         if (!strcmp(tokens[1], "VAC") || !strcmp(tokens[1], "VDC")) {
 248                 analog.meaning->mq = SR_MQ_VOLTAGE;
 249                 analog.meaning->unit = SR_UNIT_VOLT;
 250                 if (!strcmp(tokens[2], "NORMAL")) {
 251                         if (tokens[1][1] == 'A') {
 252                                 analog.meaning->mqflags |= SR_MQFLAG_AC;
 253                                 analog.meaning->mqflags |= SR_MQFLAG_RMS;
 254                         } else
 255                                 analog.meaning->mqflags |= SR_MQFLAG_DC;
 256                 } else if (!strcmp(tokens[2], "OL") || !strcmp(tokens[2], "OL_MINUS")) {
 257                         fvalue = NAN;
 258                 } else
 259                         analog.meaning->mq = 0;
 260         } else if (!strcmp(tokens[1], "dBV") || !strcmp(tokens[1], "dBm")) {
 261                 analog.meaning->mq = SR_MQ_VOLTAGE;
 262                 if (tokens[1][2] == 'm')
 263                         analog.meaning->unit = SR_UNIT_DECIBEL_MW;
 264                 else
 265                         analog.meaning->unit = SR_UNIT_DECIBEL_VOLT;
 266                 analog.meaning->mqflags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
 267         } else if (!strcmp(tokens[1], "CEL") || !strcmp(tokens[1], "FAR")) {
 268                 if (!strcmp(tokens[2], "NORMAL")) {
 269                         analog.meaning->mq = SR_MQ_TEMPERATURE;
 270                         if (tokens[1][0] == 'C')
 271                                 analog.meaning->unit = SR_UNIT_CELSIUS;
 272                         else
 273                                 analog.meaning->unit = SR_UNIT_FAHRENHEIT;
 274                 }
 275         } else if (!strcmp(tokens[1], "OHM")) {
 276                 if (!strcmp(tokens[3], "NONE")) {
 277                         analog.meaning->mq = SR_MQ_RESISTANCE;
 278                         analog.meaning->unit = SR_UNIT_OHM;
 279                         if (!strcmp(tokens[2], "OL") || !strcmp(tokens[2], "OL_MINUS")) {
 280                                 fvalue = INFINITY;
 281                         } else if (strcmp(tokens[2], "NORMAL"))
 282                                 analog.meaning->mq = 0;
 283                 } else if (!strcmp(tokens[3], "OPEN_CIRCUIT")) {
 284                         analog.meaning->mq = SR_MQ_CONTINUITY;
 285                         analog.meaning->unit = SR_UNIT_BOOLEAN;
 286                         fvalue = 0.0;
 287                 } else if (!strcmp(tokens[3], "SHORT_CIRCUIT")) {
 288                         analog.meaning->mq = SR_MQ_CONTINUITY;
 289                         analog.meaning->unit = SR_UNIT_BOOLEAN;
 290                         fvalue = 1.0;
 291                 }
 292         } else if (!strcmp(tokens[1], "F")
 293                         && !strcmp(tokens[2], "NORMAL")
 294                         && !strcmp(tokens[3], "NONE")) {
 295                 analog.meaning->mq = SR_MQ_CAPACITANCE;
 296                 analog.meaning->unit = SR_UNIT_FARAD;
 297         } else if (!strcmp(tokens[1], "AAC") || !strcmp(tokens[1], "ADC")) {
 298                 analog.meaning->mq = SR_MQ_CURRENT;
 299                 analog.meaning->unit = SR_UNIT_AMPERE;
 300                 if (!strcmp(tokens[2], "NORMAL")) {
 301                         if (tokens[1][1] == 'A') {
 302                                 analog.meaning->mqflags |= SR_MQFLAG_AC;
 303                                 analog.meaning->mqflags |= SR_MQFLAG_RMS;
 304                         } else
 305                                 analog.meaning->mqflags |= SR_MQFLAG_DC;
 306                 } else if (!strcmp(tokens[2], "OL") || !strcmp(tokens[2], "OL_MINUS")) {
 307                         fvalue = NAN;
 308                 } else
 309                         analog.meaning->mq = 0;
 310         } else if (!strcmp(tokens[1], "Hz") && !strcmp(tokens[2], "NORMAL")) {
 311                 analog.meaning->mq = SR_MQ_FREQUENCY;
 312                 analog.meaning->unit = SR_UNIT_HERTZ;
 313         } else if (!strcmp(tokens[1], "PCT") && !strcmp(tokens[2], "NORMAL")) {
 314                 analog.meaning->mq = SR_MQ_DUTY_CYCLE;
 315                 analog.meaning->unit = SR_UNIT_PERCENTAGE;
 316         } else if (!strcmp(tokens[1], "S") && !strcmp(tokens[2], "NORMAL")) {
 317                 analog.meaning->mq = SR_MQ_PULSE_WIDTH;
 318                 analog.meaning->unit = SR_UNIT_SECOND;
 319         } else if (!strcmp(tokens[1], "SIE") && !strcmp(tokens[2], "NORMAL")) {
 320                 analog.meaning->mq = SR_MQ_CONDUCTANCE;
 321                 analog.meaning->unit = SR_UNIT_SIEMENS;
 322         }
 323
 324         if (analog.meaning->mq != 0) {
 325                 /* Got a measurement. */
 326                 packet.type = SR_DF_ANALOG;
 327                 packet.payload = &analog;
 328                 sr_session_send(sdi, &packet);
 329                 sr_sw_limits_update_samples_read(&devc->limits, 1);
 330         }
 331 }
 332
 333 static void handle_qm_19x_meta(const struct sr_dev_inst *sdi, char **tokens)
 334 {
 335         struct dev_context *devc;
 336         int meas_type, meas_unit, meas_char, i;
 337
 338         /* Make sure we have 7 valid tokens. */
 339         for (i = 0; tokens[i] && i < 7; i++);
 340         if (i != 7)
 341                 return;
 342
 343         if (strcmp(tokens[1], "1"))
 344                 /* Invalid measurement. */
 345                 return;
 346
 347         if (strcmp(tokens[2], "3"))
 348                 /* Only interested in input from the meter mode source. */
 349                 return;
 350
 351         devc = sdi->priv;
 352
 353         /* Measurement type 11 == absolute, 19 = relative */
 354         meas_type = strtol(tokens[0], NULL, 10);
 355         if (meas_type != 11 && meas_type != 19)
 356                 /* Device is in some mode we don't support. */
 357                 return;
 358
 359         /* We might get metadata for absolute and relative mode (if the device
 360          * is in relative mode). In that case, relative takes precedence. */
 361         if (meas_type == 11 && devc->meas_type == 19)
 362                 return;
 363
 364         meas_unit = strtol(tokens[3], NULL, 10);
 365         if (meas_unit == 0)
 366                 /* Device is turned off. Really. */
 367                 return;
 368         meas_char = strtol(tokens[4], NULL, 10);
 369
 370         devc->mq = 0;
 371         devc->unit = 0;
 372         devc->mqflags = 0;
 373
 374         switch (meas_unit) {
 375         case 1:
 376                 devc->mq = SR_MQ_VOLTAGE;
 377                 devc->unit = SR_UNIT_VOLT;
 378                 if (meas_char == 1)
 379                         devc->mqflags |= SR_MQFLAG_DC;
 380                 else if (meas_char == 2)
 381                         devc->mqflags |= SR_MQFLAG_AC;
 382                 else if (meas_char == 3)
 383                         devc->mqflags |= SR_MQFLAG_DC | SR_MQFLAG_AC;
 384                 else if (meas_char == 15)
 385                         devc->mqflags |= SR_MQFLAG_DIODE | SR_MQFLAG_DC;
 386                 break;
 387         case 2:
 388                 devc->mq = SR_MQ_CURRENT;
 389                 devc->unit = SR_UNIT_AMPERE;
 390                 if (meas_char == 1)
 391                         devc->mqflags |= SR_MQFLAG_DC;
 392                 else if (meas_char == 2)
 393                         devc->mqflags |= SR_MQFLAG_AC;
 394                 else if (meas_char == 3)
 395                         devc->mqflags |= SR_MQFLAG_DC | SR_MQFLAG_AC;
 396                 break;
 397         case 3:
 398                 if (meas_char == 1) {
 399                         devc->mq = SR_MQ_RESISTANCE;
 400                         devc->unit = SR_UNIT_OHM;
 401                 } else if (meas_char == 16) {
 402                         devc->mq = SR_MQ_CONTINUITY;
 403                         devc->unit = SR_UNIT_BOOLEAN;
 404                 }
 405                 break;
 406         case 12:
 407                 devc->mq = SR_MQ_TEMPERATURE;
 408                 devc->unit = SR_UNIT_CELSIUS;
 409                 break;
 410         case 13:
 411                 devc->mq = SR_MQ_TEMPERATURE;
 412                 devc->unit = SR_UNIT_FAHRENHEIT;
 413                 break;
 414         default:
 415                 sr_dbg("unknown unit: %d", meas_unit);
 416         }
 417         if (devc->mq == 0 && devc->unit == 0)
 418                 return;
 419
 420         /* If we got here, we know how to interpret the measurement. */
 421         devc->meas_type = meas_type;
 422         if (meas_type == 11)
 423                 /* Absolute meter reading. */
 424                 devc->is_relative = FALSE;
 425         else if (!strcmp(tokens[0], "19"))
 426                 /* Relative meter reading. */
 427                 devc->is_relative = TRUE;
 428
 429 }
 430
 431 static void handle_qm_19x_data(const struct sr_dev_inst *sdi, char **tokens)
 432 {
 433         struct dev_context *devc;
 434         struct sr_datafeed_packet packet;
 435         struct sr_datafeed_analog analog;
 436         struct sr_analog_encoding encoding;
 437         struct sr_analog_meaning meaning;
 438         struct sr_analog_spec spec;
 439         float fvalue;
 440         int digits;
 441
 442         digits = 2;
 443         if (!strcmp(tokens[0], "9.9E+37")) {
 444                 /* An invalid measurement shows up on the display as "OL", but
 445                  * comes through like this. Since comparing 38-digit floats
 446                  * is rather problematic, we'll cut through this here. */
 447                 fvalue = NAN;
 448         } else {
 449                 if (sr_atof_ascii(tokens[0], &fvalue) != SR_OK || fvalue == 0.0) {
 450                         sr_err("Invalid float '%s'.", tokens[0]);
 451                         return;
 452                 }
 453                 digits = count_digits(tokens[0]);
 454         }
 455
 456         devc = sdi->priv;
 457         if (devc->mq == 0 || devc->unit == 0)
 458                 /* Don't have valid metadata yet. */
 459                 return;
 460
 461         if (devc->mq == SR_MQ_RESISTANCE && isnan(fvalue))
 462                 fvalue = INFINITY;
 463         else if (devc->mq == SR_MQ_CONTINUITY) {
 464                 if (isnan(fvalue))
 465                         fvalue = 0.0;
 466                 else
 467                         fvalue = 1.0;
 468         }
 469
 470         sr_analog_init(&analog, &encoding, &meaning, &spec, digits);
 471         analog.meaning->channels = sdi->channels;
 472         analog.num_samples = 1;
 473         analog.data = &fvalue;
 474         analog.meaning->mq = devc->mq;
 475         analog.meaning->unit = devc->unit;
 476         analog.meaning->mqflags = 0;
 477         packet.type = SR_DF_ANALOG;
 478         packet.payload = &analog;
 479         sr_session_send(sdi, &packet);
 480
 481         sr_sw_limits_update_samples_read(&devc->limits, 1);
 482 }
 483
 484 static void handle_line(const struct sr_dev_inst *sdi)
 485 {
 486         struct dev_context *devc;
 487         struct sr_serial_dev_inst *serial;
 488         int num_tokens, n, i;
 489         char cmd[16], **tokens;
 490         int ret;
 491
 492         devc = sdi->priv;
 493         serial = sdi->conn;
 494         sr_spew("Received line '%s' (%d).", devc->buf, devc->buflen);
 495
 496         if (devc->buflen == 1) {
 497                 if (devc->buf[0] != '0') {
 498                         /* Not just a CMD_ACK from the query command. */
 499                         sr_dbg("Got CMD_ACK '%c'.", devc->buf[0]);
 500                         devc->expect_response = FALSE;
 501                 }
 502                 devc->buflen = 0;
 503                 return;
 504         }
 505
 506         tokens = g_strsplit(devc->buf, ",", 0);
 507         if (tokens[0]) {
 508                 switch (devc->profile->model) {
 509                 case FLUKE_87:
 510                 case FLUKE_89:
 511                 case FLUKE_187:
 512                 case FLUKE_189:
 513                         devc->expect_response = FALSE;
 514                         handle_qm_18x(sdi, tokens);
 515                         break;
 516                 case FLUKE_190:
 517                         devc->expect_response = FALSE;
 518                         num_tokens = g_strv_length(tokens);
 519                         if (num_tokens < 7) {
 520                                 /* Response to QM <n> measurement request. */
 521                                 handle_qm_19x_data(sdi, tokens);
 522                                 break;
 523                         }
 524                         /*
 525                          * Response to QM: This is a comma-separated list of
 526                          * fields with metadata about the measurement. This
 527                          * format can return multiple sets of metadata,
 528                          * split into sets of 7 tokens each.
 529                          */
 530                         devc->meas_type = 0;
 531                         for (i = 0; i < num_tokens; i += 7)
 532                                 handle_qm_19x_meta(sdi, tokens + i);
 533                         if (devc->meas_type) {
 534                                 /*
 535                                  * Slip the request in now, before the main
 536                                  * timer loop asks for metadata again.
 537                                  */
 538                                 n = sprintf(cmd, "QM %d\r", devc->meas_type);
 539                                 ret = serial_write_blocking(serial,
 540                                         cmd, n, SERIAL_WRITE_TIMEOUT_MS);
 541                                 if (ret < 0)
 542                                         sr_err("Cannot send QM (measurement).");
 543                         }
 544                         break;
 545                 case FLUKE_287:
 546                 case FLUKE_289:
 547                         devc->expect_response = FALSE;
 548                         handle_qm_28x(sdi, tokens);
 549                         break;
 550                 }
 551         }
 552         g_strfreev(tokens);
 553         devc->buflen = 0;
 554 }
 555
 556 SR_PRIV int fluke_receive_data(int fd, int revents, void *cb_data)
 557 {
 558         struct sr_dev_inst *sdi;
 559         struct dev_context *devc;
 560         struct sr_serial_dev_inst *serial;
 561         int len;
 562         int64_t now, elapsed;
 563
 564         (void)fd;
 565
 566         if (!(sdi = cb_data))
 567                 return TRUE;
 568
 569         if (!(devc = sdi->priv))
 570                 return TRUE;
 571
 572         serial = sdi->conn;
 573         if (revents == G_IO_IN) {
 574                 /* Serial data arrived. */
 575                 while (FLUKEDMM_BUFSIZE - devc->buflen - 1 > 0) {
 576                         len = serial_read_nonblocking(serial, devc->buf + devc->buflen, 1);
 577                         if (len < 1)
 578                                 break;
 579                         devc->buflen++;
 580                         *(devc->buf + devc->buflen) = '\0';
 581                         if (*(devc->buf + devc->buflen - 1) == '\r') {
 582                                 *(devc->buf + --devc->buflen) = '\0';
 583                                 handle_line(sdi);
 584                                 break;
 585                         }
 586                 }
 587         }
 588
 589         if (sr_sw_limits_check(&devc->limits)) {
 590                 sr_dev_acquisition_stop(sdi);
 591                 return TRUE;
 592         }
 593
 594         now = g_get_monotonic_time() / 1000;
 595         elapsed = now - devc->cmd_sent_at;
 596         /* Send query command at poll_period interval, or after 1 second
 597          * has elapsed. This will make it easier to recover from any
 598          * out-of-sync or temporary disconnect issues. */
 599         if ((devc->expect_response == FALSE && elapsed > devc->profile->poll_period)
 600                         || elapsed > devc->profile->timeout) {
 601                 if (serial_write_blocking(serial, "QM\r", 3, SERIAL_WRITE_TIMEOUT_MS) < 0)
 602                         sr_err("Unable to send QM.");
 603                 devc->cmd_sent_at = now;
 604                 devc->expect_response = TRUE;
 605         }
 606
 607         return TRUE;
 608 }