src/hardware/scpi-dmm/api.c

   1 /*
   2  * This file is part of the libsigrok project.
   3  *
   4  * Copyright (C) 2018 Gerhard Sittig <gerhard.sittig@gmx.net>
   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 <string.h>
  21 #include "protocol.h"
  22
  23 static struct sr_dev_driver scpi_dmm_driver_info;
  24
  25 static const uint32_t scanopts[] = {
  26         SR_CONF_CONN,
  27         SR_CONF_SERIALCOMM,
  28 };
  29
  30 static const uint32_t drvopts[] = {
  31         SR_CONF_MULTIMETER,
  32 };
  33
  34 static const uint32_t devopts_generic[] = {
  35         SR_CONF_CONTINUOUS,
  36         SR_CONF_CONN | SR_CONF_GET,
  37         SR_CONF_LIMIT_SAMPLES | SR_CONF_GET | SR_CONF_SET,
  38         SR_CONF_LIMIT_MSEC | SR_CONF_GET | SR_CONF_SET,
  39         SR_CONF_MEASURED_QUANTITY | SR_CONF_GET | SR_CONF_SET | SR_CONF_LIST,
  40 };
  41
  42 static const struct scpi_command cmdset_agilent[] = {
  43         { DMM_CMD_SETUP_REMOTE, "\n", },
  44         { DMM_CMD_SETUP_FUNC, "CONF:%s", },
  45         { DMM_CMD_QUERY_FUNC, "CONF?", },
  46         { DMM_CMD_START_ACQ, "MEAS", },
  47         { DMM_CMD_STOP_ACQ, "ABORT", },
  48         { DMM_CMD_QUERY_VALUE, "READ?", },
  49         { DMM_CMD_QUERY_PREC, "CONF?", },
  50         ALL_ZERO,
  51 };
  52
  53 /*
  54  * cmdset_hp is used for the 34401A, which was added to this code after the
  55  * 34405A and 34465A. It differs in starting the measurement with INIT: using
  56  * MEAS without a trailing '?' (as used for the 34405A) is not valid for the
  57  * 34401A and gives an error.
  58  * I'm surprised the same instruction sequence doesn't work and INIT may
  59  * work for both, but I don't have the others to re-test.
  60  *
  61  * cmdset_hp also works well for the 34410A, using cmdset_agilent throws an
  62  * error on 'MEAS' without a '?'.
  63  *
  64  * On the 34401A,
  65  *  MEAS <optional parameters> ? configures, arms, triggers and waits
  66  *       for a reading
  67  *  CONF <parameters> configures
  68  *  INIT prepares for triggering (trigger mode is not set, assumed
  69  *       internal - external might time out)
  70  *  *OPC waits for completion, and
  71  *  READ? retrieves the result
  72  */
  73 static const struct scpi_command cmdset_hp[] = {
  74         { DMM_CMD_SETUP_REMOTE, "\n", },
  75         { DMM_CMD_SETUP_FUNC, "CONF:%s", },
  76         { DMM_CMD_QUERY_FUNC, "CONF?", },
  77         { DMM_CMD_START_ACQ, "INIT", },
  78         { DMM_CMD_STOP_ACQ, "ABORT", },
  79         { DMM_CMD_QUERY_VALUE, "READ?", },
  80         { DMM_CMD_QUERY_PREC, "CONF?", },
  81         ALL_ZERO,
  82 };
  83
  84 static const struct scpi_command cmdset_gwinstek[] = {
  85         { DMM_CMD_SETUP_REMOTE, "SYST:REM", },
  86         { DMM_CMD_SETUP_LOCAL, "SYST:LOC", },
  87         { DMM_CMD_SETUP_FUNC, "CONF:%s", },
  88         { DMM_CMD_QUERY_FUNC, "CONF:STAT:FUNC?", },
  89         { DMM_CMD_START_ACQ, "*CLS;SYST:REM", },
  90         { DMM_CMD_QUERY_VALUE, "VAL1?", },
  91         { DMM_CMD_QUERY_PREC, "SENS:DET:RATE?", },
  92         ALL_ZERO,
  93 };
  94
  95 static const struct scpi_command cmdset_gwinstek_906x[] = {
  96         { DMM_CMD_SETUP_REMOTE, "SYST:REM", },
  97         { DMM_CMD_SETUP_LOCAL, "SYST:LOC", },
  98         { DMM_CMD_SETUP_FUNC, "CONF:%s", },
  99         { DMM_CMD_QUERY_FUNC, "CONF?", },
 100         { DMM_CMD_START_ACQ, "INIT", },
 101         { DMM_CMD_STOP_ACQ, "ABORT", },
 102         { DMM_CMD_QUERY_VALUE, "VAL1?", },
 103         { DMM_CMD_QUERY_PREC, "SENS:DET:RATE?", },
 104         ALL_ZERO,
 105 };
 106
 107 static const struct mqopt_item mqopts_agilent_34405a[] = {
 108         { SR_MQ_VOLTAGE, SR_MQFLAG_DC, "VOLT:DC", "VOLT ", NO_DFLT_PREC, },
 109         { SR_MQ_VOLTAGE, SR_MQFLAG_AC, "VOLT:AC", "VOLT:AC ", NO_DFLT_PREC, },
 110         { SR_MQ_CURRENT, SR_MQFLAG_DC, "CURR:DC", "CURR ", NO_DFLT_PREC, },
 111         { SR_MQ_CURRENT, SR_MQFLAG_AC, "CURR:AC", "CURR:AC ", NO_DFLT_PREC, },
 112         { SR_MQ_RESISTANCE, 0, "RES", "RES ", NO_DFLT_PREC, },
 113         { SR_MQ_CONTINUITY, 0, "CONT", "CONT", -1, },
 114         { SR_MQ_CAPACITANCE, 0, "CAP", "CAP ", NO_DFLT_PREC, },
 115         { SR_MQ_VOLTAGE, SR_MQFLAG_DC | SR_MQFLAG_DIODE, "DIOD", "DIOD", -4, },
 116         { SR_MQ_TEMPERATURE, 0, "TEMP", "TEMP ", NO_DFLT_PREC, },
 117         { SR_MQ_FREQUENCY, 0, "FREQ", "FREQ ", NO_DFLT_PREC, },
 118 };
 119
 120 static const struct mqopt_item mqopts_agilent_34401a[] = {
 121         { SR_MQ_VOLTAGE, SR_MQFLAG_DC, "VOLT:DC", "VOLT ", NO_DFLT_PREC, },
 122         { SR_MQ_VOLTAGE, SR_MQFLAG_AC, "VOLT:AC", "VOLT:AC ", NO_DFLT_PREC, },
 123         { SR_MQ_CURRENT, SR_MQFLAG_DC, "CURR:DC", "CURR ", NO_DFLT_PREC, },
 124         { SR_MQ_CURRENT, SR_MQFLAG_AC, "CURR:AC", "CURR:AC ", NO_DFLT_PREC, },
 125         { SR_MQ_RESISTANCE, 0, "RES", "RES ", NO_DFLT_PREC, },
 126         { SR_MQ_RESISTANCE, SR_MQFLAG_FOUR_WIRE, "FRES", "FRES ", NO_DFLT_PREC, },
 127         { SR_MQ_CONTINUITY, 0, "CONT", "CONT", -1, },
 128         { SR_MQ_VOLTAGE, SR_MQFLAG_DC | SR_MQFLAG_DIODE, "DIOD", "DIOD", -4, },
 129         { SR_MQ_FREQUENCY, 0, "FREQ", "FREQ ", NO_DFLT_PREC, },
 130         { SR_MQ_TIME, 0, "PER", "PER ", NO_DFLT_PREC, },
 131 };
 132
 133 static const struct mqopt_item mqopts_gwinstek_gdm8200a[] = {
 134         { SR_MQ_VOLTAGE, SR_MQFLAG_DC, "VOLT:DC", "01", NO_DFLT_PREC, },
 135         { SR_MQ_VOLTAGE, SR_MQFLAG_AC, "VOLT:AC", "02", NO_DFLT_PREC, },
 136         { SR_MQ_CURRENT, SR_MQFLAG_DC, "CURR:DC", "03", NO_DFLT_PREC, },
 137         { SR_MQ_CURRENT, SR_MQFLAG_AC, "CURR:AC", "04", NO_DFLT_PREC, },
 138         { SR_MQ_CURRENT, SR_MQFLAG_DC, "CURR:DC", "05", NO_DFLT_PREC, }, /* mA */
 139         { SR_MQ_CURRENT, SR_MQFLAG_AC, "CURR:AC", "06", NO_DFLT_PREC, }, /* mA */
 140         { SR_MQ_RESISTANCE, 0, "RES", "07", NO_DFLT_PREC, },
 141         { SR_MQ_RESISTANCE, SR_MQFLAG_FOUR_WIRE, "FRES", "16", NO_DFLT_PREC, },
 142         { SR_MQ_CONTINUITY, 0, "CONT", "13", -1, },
 143         { SR_MQ_VOLTAGE, SR_MQFLAG_DC | SR_MQFLAG_DIODE, "DIOD", "17", -4, },
 144         { SR_MQ_TEMPERATURE, 0, "TEMP", "09", NO_DFLT_PREC, }, /* Celsius */
 145         { SR_MQ_TEMPERATURE, 0, "TEMP", "15", NO_DFLT_PREC, }, /* Fahrenheit */
 146         { SR_MQ_FREQUENCY, 0, "FREQ", "08", NO_DFLT_PREC, },
 147         { SR_MQ_TIME, 0, "PER", "14", NO_DFLT_PREC, },
 148 };
 149
 150 static const struct mqopt_item mqopts_gwinstek_gdm906x[] = {
 151         { SR_MQ_VOLTAGE, SR_MQFLAG_DC, "VOLT:DC", "VOLT ", NO_DFLT_PREC, },
 152         { SR_MQ_VOLTAGE, SR_MQFLAG_AC, "VOLT:AC", "VOLT:AC", NO_DFLT_PREC, },
 153         { SR_MQ_CURRENT, SR_MQFLAG_DC, "CURR:DC", "CURR ", NO_DFLT_PREC, },
 154         { SR_MQ_CURRENT, SR_MQFLAG_AC, "CURR:AC", "CURR:AC", NO_DFLT_PREC, },
 155         { SR_MQ_RESISTANCE, 0, "RES", "RES", NO_DFLT_PREC, },
 156         { SR_MQ_RESISTANCE, SR_MQFLAG_FOUR_WIRE, "FRES", "FRES", NO_DFLT_PREC, },
 157         { SR_MQ_CONTINUITY, 0, "CONT", "CONT", -1, },
 158         { SR_MQ_VOLTAGE, SR_MQFLAG_DC | SR_MQFLAG_DIODE, "DIOD", "DIOD", -4, },
 159         { SR_MQ_TEMPERATURE, 0, "TEMP", "TEMP", NO_DFLT_PREC, },
 160         { SR_MQ_FREQUENCY, 0, "FREQ", "FREQ", NO_DFLT_PREC, },
 161         { SR_MQ_TIME, 0, "PER", "PER", NO_DFLT_PREC, },
 162         { SR_MQ_CAPACITANCE, 0, "CAP", "CAP", NO_DFLT_PREC, },
 163 };
 164
 165 SR_PRIV const struct scpi_dmm_model models[] = {
 166         {
 167                 "Agilent", "34405A",
 168                 1, 5, cmdset_agilent, ARRAY_AND_SIZE(mqopts_agilent_34405a),
 169                 scpi_dmm_get_meas_agilent,
 170                 ARRAY_AND_SIZE(devopts_generic),
 171                 0,
 172         },
 173         {
 174                 "Agilent", "34410A",
 175                 1, 6, cmdset_hp, ARRAY_AND_SIZE(mqopts_agilent_34405a),
 176                 scpi_dmm_get_meas_agilent,
 177                 ARRAY_AND_SIZE(devopts_generic),
 178                 0,
 179         },
 180         {
 181                 "GW", "GDM8251A",
 182                 1, 6, cmdset_gwinstek, ARRAY_AND_SIZE(mqopts_gwinstek_gdm8200a),
 183                 scpi_dmm_get_meas_gwinstek,
 184                 ARRAY_AND_SIZE(devopts_generic),
 185                 1000 * 2500,
 186         },
 187         {
 188                 "GW", "GDM8255A",
 189                 1, 6, cmdset_gwinstek, ARRAY_AND_SIZE(mqopts_gwinstek_gdm8200a),
 190                 scpi_dmm_get_meas_gwinstek,
 191                 ARRAY_AND_SIZE(devopts_generic),
 192                 1000 * 2500,
 193         },
 194         {
 195                 "GWInstek", "GDM9060",
 196                 1, 6, cmdset_gwinstek_906x, ARRAY_AND_SIZE(mqopts_gwinstek_gdm906x),
 197                 scpi_dmm_get_meas_agilent,
 198                 ARRAY_AND_SIZE(devopts_generic),
 199                 0,
 200         },
 201         {
 202                 "GWInstek", "GDM9061",
 203                 1, 6, cmdset_gwinstek_906x, ARRAY_AND_SIZE(mqopts_gwinstek_gdm906x),
 204                 scpi_dmm_get_meas_agilent,
 205                 ARRAY_AND_SIZE(devopts_generic),
 206                 0,
 207         },
 208         {
 209                 "HP", "34401A",
 210                 1, 6, cmdset_hp, ARRAY_AND_SIZE(mqopts_agilent_34401a),
 211                 scpi_dmm_get_meas_agilent,
 212                 ARRAY_AND_SIZE(devopts_generic),
 213                 /* 34401A: typ. 1020ms for AC readings (default is 1000ms). */
 214                 1000 * 1500,
 215         },
 216         {
 217                 "Keysight", "34465A",
 218                 1, 5, cmdset_agilent, ARRAY_AND_SIZE(mqopts_agilent_34405a),
 219                 scpi_dmm_get_meas_agilent,
 220                 ARRAY_AND_SIZE(devopts_generic),
 221                 0,
 222         },
 223 };
 224
 225 static const struct scpi_dmm_model *is_compatible(const char *vendor, const char *model)
 226 {
 227         size_t i;
 228         const struct scpi_dmm_model *entry;
 229
 230         for (i = 0; i < ARRAY_SIZE(models); i++) {
 231                 entry = &models[i];
 232                 if (!entry->vendor || !entry->model)
 233                         continue;
 234                 if (strcmp(vendor, entry->vendor) != 0)
 235                         continue;
 236                 if (strcmp(model, entry->model) != 0)
 237                         continue;
 238                 return entry;
 239         }
 240
 241         return NULL;
 242 }
 243
 244 static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 245 {
 246         struct sr_scpi_hw_info *hw_info;
 247         int ret;
 248         const char *vendor;
 249         const struct scpi_dmm_model *model;
 250         struct sr_dev_inst *sdi;
 251         struct dev_context *devc;
 252         size_t i;
 253         gchar *channel_name;
 254         const char *command;
 255
 256         scpi_dmm_cmd_delay(scpi);
 257         ret = sr_scpi_get_hw_id(scpi, &hw_info);
 258         if (ret != SR_OK) {
 259                 sr_info("Could not get IDN response.");
 260                 return NULL;
 261         }
 262         vendor = sr_vendor_alias(hw_info->manufacturer);
 263         model = is_compatible(vendor, hw_info->model);
 264         if (!model) {
 265                 sr_scpi_hw_info_free(hw_info);
 266                 return NULL;
 267         }
 268
 269         sdi = g_malloc0(sizeof(*sdi));
 270         sdi->vendor = g_strdup(hw_info->manufacturer);
 271         sdi->model = g_strdup(hw_info->model);
 272         sdi->version = g_strdup(hw_info->firmware_version);
 273         sdi->serial_num = g_strdup(hw_info->serial_number);
 274         sdi->conn = scpi;
 275         sdi->driver = &scpi_dmm_driver_info;
 276         sdi->inst_type = SR_INST_SCPI;
 277         ret = sr_scpi_connection_id(scpi, &sdi->connection_id);
 278         if (ret != SR_OK) {
 279                 g_free(sdi->connection_id);
 280                 sdi->connection_id = NULL;
 281         }
 282         sr_scpi_hw_info_free(hw_info);
 283         if (model->read_timeout_us)  /* non-default read timeout */
 284                 scpi->read_timeout_us = model->read_timeout_us;
 285         devc = g_malloc0(sizeof(*devc));
 286         sdi->priv = devc;
 287         devc->num_channels = model->num_channels;
 288         devc->cmdset = model->cmdset;
 289         devc->model = model;
 290
 291         for (i = 0; i < devc->num_channels; i++) {
 292                 channel_name = g_strdup_printf("P%zu", i + 1);
 293                 sr_channel_new(sdi, 0, SR_CHANNEL_ANALOG, TRUE, channel_name);
 294         }
 295
 296         /*
 297          * If device has DMM_CMD_SETUP_LOCAL command, send it now. To avoid
 298          * leaving device in remote mode (if only a "scan" is run).
 299          */
 300         command = sr_scpi_cmd_get(devc->cmdset, DMM_CMD_SETUP_LOCAL);
 301         if (command && *command) {
 302                 scpi_dmm_cmd_delay(scpi);
 303                 sr_scpi_send(scpi, command);
 304         }
 305
 306         return sdi;
 307 }
 308
 309 static GSList *scan(struct sr_dev_driver *di, GSList *options)
 310 {
 311         return sr_scpi_scan(di->context, options, probe_device);
 312 }
 313
 314 static int dev_open(struct sr_dev_inst *sdi)
 315 {
 316         struct sr_scpi_dev_inst *scpi;
 317         int ret;
 318
 319         scpi = sdi->conn;
 320         ret = sr_scpi_open(scpi);
 321         if (ret < 0) {
 322                 sr_err("Failed to open SCPI device: %s.", sr_strerror(ret));
 323                 return SR_ERR;
 324         }
 325
 326         return SR_OK;
 327 }
 328
 329 static int dev_close(struct sr_dev_inst *sdi)
 330 {
 331         struct dev_context *devc;
 332         struct sr_scpi_dev_inst *scpi;
 333         const char *command;
 334
 335         devc = sdi->priv;
 336         scpi = sdi->conn;
 337         if (!scpi)
 338                 return SR_ERR_BUG;
 339
 340         sr_dbg("DIAG: sdi->status %d.", sdi->status - SR_ST_NOT_FOUND);
 341         if (sdi->status <= SR_ST_INACTIVE)
 342                 return SR_OK;
 343
 344         /*
 345          * If device has DMM_CMD_SETUP_LOCAL command, send it now
 346          * to avoid leaving device in remote mode.
 347          */
 348         command = sr_scpi_cmd_get(devc->cmdset, DMM_CMD_SETUP_LOCAL);
 349         if (command && *command) {
 350                 scpi_dmm_cmd_delay(scpi);
 351                 sr_scpi_send(scpi, command);
 352         }
 353
 354         return sr_scpi_close(scpi);
 355 }
 356
 357 static int config_get(uint32_t key, GVariant **data,
 358         const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 359 {
 360         struct dev_context *devc;
 361         enum sr_mq mq;
 362         enum sr_mqflag mqflag;
 363         GVariant *arr[2];
 364         int ret;
 365
 366         (void)cg;
 367
 368         devc = sdi->priv;
 369
 370         switch (key) {
 371         case SR_CONF_CONN:
 372                 if (!sdi || !sdi->connection_id)
 373                         return SR_ERR_NA;
 374                 *data = g_variant_new_string(sdi->connection_id);
 375                 return SR_OK;
 376         case SR_CONF_LIMIT_SAMPLES:
 377         case SR_CONF_LIMIT_MSEC:
 378                 return sr_sw_limits_config_get(&devc->limits, key, data);
 379         case SR_CONF_MEASURED_QUANTITY:
 380                 ret = scpi_dmm_get_mq(sdi, &mq, &mqflag, NULL, NULL);
 381                 if (ret != SR_OK)
 382                         return ret;
 383                 arr[0] = g_variant_new_uint32(mq);
 384                 arr[1] = g_variant_new_uint64(mqflag);
 385                 *data = g_variant_new_tuple(arr, ARRAY_SIZE(arr));
 386                 return SR_OK;
 387         default:
 388                 return SR_ERR_NA;
 389         }
 390 }
 391
 392 static int config_set(uint32_t key, GVariant *data,
 393         const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 394 {
 395         struct dev_context *devc;
 396         enum sr_mq mq;
 397         enum sr_mqflag mqflag;
 398         GVariant *tuple_child;
 399
 400         (void)cg;
 401
 402         devc = sdi->priv;
 403
 404         switch (key) {
 405         case SR_CONF_LIMIT_SAMPLES:
 406         case SR_CONF_LIMIT_MSEC:
 407                 return sr_sw_limits_config_set(&devc->limits, key, data);
 408         case SR_CONF_MEASURED_QUANTITY:
 409                 tuple_child = g_variant_get_child_value(data, 0);
 410                 mq = g_variant_get_uint32(tuple_child);
 411                 g_variant_unref(tuple_child);
 412                 tuple_child = g_variant_get_child_value(data, 1);
 413                 mqflag = g_variant_get_uint64(tuple_child);
 414                 g_variant_unref(tuple_child);
 415                 return scpi_dmm_set_mq(sdi, mq, mqflag);
 416         default:
 417                 return SR_ERR_NA;
 418         }
 419 }
 420
 421 static int config_list(uint32_t key, GVariant **data,
 422         const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 423 {
 424         struct dev_context *devc;
 425         GVariant *gvar, *arr[2];
 426         GVariantBuilder gvb;
 427         size_t i;
 428
 429         (void)cg;
 430
 431         devc = sdi ? sdi->priv : NULL;
 432
 433         switch (key) {
 434         case SR_CONF_SCAN_OPTIONS:
 435         case SR_CONF_DEVICE_OPTIONS:
 436                 if (!devc)
 437                         return STD_CONFIG_LIST(key, data, sdi, cg,
 438                                 scanopts, drvopts, devopts_generic);
 439                 return std_opts_config_list(key, data, sdi, cg,
 440                         ARRAY_AND_SIZE(scanopts), ARRAY_AND_SIZE(drvopts),
 441                         devc->model->devopts, devc->model->devopts_size);
 442         case SR_CONF_MEASURED_QUANTITY:
 443                 /* TODO Use std_gvar_measured_quantities() when available. */
 444                 if (!devc)
 445                         return SR_ERR_ARG;
 446                 g_variant_builder_init(&gvb, G_VARIANT_TYPE_ARRAY);
 447                 for (i = 0; i < devc->model->mqopt_size; i++) {
 448                         arr[0] = g_variant_new_uint32(devc->model->mqopts[i].mq);
 449                         arr[1] = g_variant_new_uint64(devc->model->mqopts[i].mqflag);
 450                         gvar = g_variant_new_tuple(arr, ARRAY_SIZE(arr));
 451                         g_variant_builder_add_value(&gvb, gvar);
 452                 }
 453                 *data = g_variant_builder_end(&gvb);
 454                 return SR_OK;
 455         default:
 456                 (void)devc;
 457                 return SR_ERR_NA;
 458         }
 459 }
 460
 461 static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 462 {
 463         struct sr_scpi_dev_inst *scpi;
 464         struct dev_context *devc;
 465         int ret;
 466         const struct mqopt_item *item;
 467         const char *command;
 468         char *response;
 469
 470         scpi = sdi->conn;
 471         devc = sdi->priv;
 472
 473         ret = scpi_dmm_get_mq(sdi, &devc->start_acq_mq.curr_mq,
 474                 &devc->start_acq_mq.curr_mqflag, NULL, &item);
 475         if (ret != SR_OK)
 476                 return ret;
 477
 478         /*
 479          * Query for current precision if DMM supports the command
 480          */
 481         command = sr_scpi_cmd_get(devc->cmdset, DMM_CMD_QUERY_PREC);
 482         if (command && *command) {
 483                 scpi_dmm_cmd_delay(scpi);
 484                 ret = sr_scpi_get_string(scpi, command, &response);
 485                 if (ret == SR_OK) {
 486                         g_strstrip(response);
 487                         g_free(devc->precision);
 488                         devc->precision = g_strdup(response);
 489                         g_free(response);
 490                         sr_dbg("%s: Precision: '%s'", __func__, devc->precision);
 491                 } else {
 492                         sr_info("Precision query ('%s') failed: %d",
 493                                 command, ret);
 494                 }
 495         }
 496
 497         command = sr_scpi_cmd_get(devc->cmdset, DMM_CMD_START_ACQ);
 498         if (command && *command) {
 499                 scpi_dmm_cmd_delay(scpi);
 500                 ret = sr_scpi_send(scpi, command);
 501                 if (ret != SR_OK)
 502                         return ret;
 503         }
 504
 505         sr_sw_limits_acquisition_start(&devc->limits);
 506         ret = std_session_send_df_header(sdi);
 507         if (ret != SR_OK)
 508                 return ret;
 509
 510         ret = sr_scpi_source_add(sdi->session, scpi, G_IO_IN, 10,
 511                 scpi_dmm_receive_data, (void *)sdi);
 512         if (ret != SR_OK)
 513                 return ret;
 514
 515         return SR_OK;
 516 }
 517
 518 static int dev_acquisition_stop(struct sr_dev_inst *sdi)
 519 {
 520         struct sr_scpi_dev_inst *scpi;
 521         struct dev_context *devc;
 522         const char *command;
 523
 524         scpi = sdi->conn;
 525         devc = sdi->priv;
 526
 527         command = sr_scpi_cmd_get(devc->cmdset, DMM_CMD_STOP_ACQ);
 528         if (command && *command) {
 529                 scpi_dmm_cmd_delay(scpi);
 530                 (void)sr_scpi_send(scpi, command);
 531         }
 532         sr_scpi_source_remove(sdi->session, scpi);
 533
 534         std_session_send_df_end(sdi);
 535
 536         g_free(devc->precision);
 537         devc->precision = NULL;
 538
 539         return SR_OK;
 540 }
 541
 542 static struct sr_dev_driver scpi_dmm_driver_info = {
 543         .name = "scpi-dmm",
 544         .longname = "SCPI DMM",
 545         .api_version = 1,
 546         .init = std_init,
 547         .cleanup = std_cleanup,
 548         .scan = scan,
 549         .dev_list = std_dev_list,
 550         .dev_clear = std_dev_clear,
 551         .config_get = config_get,
 552         .config_set = config_set,
 553         .config_list = config_list,
 554         .dev_open = dev_open,
 555         .dev_close = dev_close,
 556         .dev_acquisition_start = dev_acquisition_start,
 557         .dev_acquisition_stop = dev_acquisition_stop,
 558         .context = NULL,
 559 };
 560 SR_REGISTER_DEV_DRIVER(scpi_dmm_driver_info);