]> sigrok.org Git - libsigrok.git/blobdiff - src/hardware/rdtech-dps/protocol.c
rdtech-dps: Use big endian register access for DPS devices
[libsigrok.git] / src / hardware / rdtech-dps / protocol.c
index 6f1d48670b62b87288e601e5c99b5dab4b0cdc44..83090d86ac7c2253c6662a305b7beab10015df67 100644 (file)
@@ -3,6 +3,7 @@
  *
  * Copyright (C) 2018 James Churchill <pelrun@gmail.com>
  * Copyright (C) 2019 Frank Stettner <frank-stettner@gmx.net>
+ * Copyright (C) 2021 Gerhard Sittig <gerhard.sittig@gmx.net>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  */
 
 #include <config.h>
+
+#include <string.h>
+
 #include "protocol.h"
 
-SR_PRIV int rdtech_dps_read_holding_registers(struct sr_modbus_dev_inst *modbus,
-               int address, int nb_registers, uint16_t *registers)
+enum rdtech_dps_register {
+       REG_DPS_USET       = 0x00, /* Mirror of 0x50 */
+       REG_DPS_ISET       = 0x01, /* Mirror of 0x51 */
+       REG_DPS_UOUT       = 0x02,
+       REG_DPS_IOUT       = 0x03,
+       REG_DPS_POWER      = 0x04,
+       REG_DPS_UIN        = 0x05,
+       REG_DPS_LOCK       = 0x06,
+       REG_DPS_PROTECT    = 0x07,
+       REG_DPS_CV_CC      = 0x08,
+       REG_DPS_ENABLE     = 0x09,
+       REG_DPS_BACKLIGHT  = 0x0A, /* Mirror of 0x55 */
+       REG_DPS_MODEL      = 0x0B,
+       REG_DPS_VERSION    = 0x0C,
+
+       REG_DPS_PRESET     = 0x23, /* Loads a preset into preset 0. */
+
+       /*
+        * Add (preset * 0x10) to each of the following, for preset 1-9.
+        * Preset 0 regs below are the active output settings.
+        */
+       PRE_DPS_USET       = 0x50,
+       PRE_DPS_ISET       = 0x51,
+       PRE_DPS_OVPSET     = 0x52,
+       PRE_DPS_OCPSET     = 0x53,
+       PRE_DPS_OPPSET     = 0x54,
+       PRE_DPS_BACKLIGHT  = 0x55,
+       PRE_DPS_DISABLE    = 0x56, /* Disable output if 0 is copied here from a preset (1 is no change). */
+       PRE_DPS_BOOT       = 0x57, /* Enable output at boot if 1. */
+};
+#define PRE_DPS_STRIDE 0x10
+
+enum rdtech_dps_protect_state {
+       STATE_NORMAL = 0,
+       STATE_OVP    = 1,
+       STATE_OCP    = 2,
+       STATE_OPP    = 3,
+};
+
+enum rdtech_dps_regulation_mode {
+       MODE_CV      = 0,
+       MODE_CC      = 1,
+};
+
+enum rdtech_rd_register {
+       REG_RD_MODEL = 0, /* u16 */
+       REG_RD_SERIAL = 1, /* u32 */
+       REG_RD_FIRMWARE = 3, /* u16 */
+       REG_RD_TEMP_INT = 4, /* 2x u16 */
+       REG_RD_TEMP_INT_F = 6, /* 2x u16 */
+       REG_RD_VOLT_TGT = 8, /* u16 */
+       REG_RD_CURR_LIM = 9, /* u16 */
+       REG_RD_VOLTAGE = 10, /* u16 */
+       REG_RD_CURRENT = 11, /* u16 */
+       REG_RD_ENERGY = 12, /* u16 */
+       REG_RD_POWER = 13, /* u16 */
+       REG_RD_VOLT_IN = 14, /* u16 */
+       REG_RD_PROTECT = 16, /* u16 */
+       REG_RD_REGULATION = 17, /* u16 */
+       REG_RD_ENABLE = 18, /* u16 */
+       /*
+        * Battery at 32 == 0x20 pp:
+        * Mode, voltage, temperature, capacity, energy.
+        */
+       /*
+        * Date/time at 48 == 0x30 pp:
+        * Year, month, day, hour, minute, second.
+        */
+       /* Backlight at 72 == 0x48. */
+       REG_RD_OVP_THR = 82, /* 0x52 */
+       REG_RD_OCP_THR = 83, /* 0x53 */
+       /* One "live" slot and 9 "memory" positions. */
+       REG_RD_START_MEM = 84, /* 0x54 */
+};
+
+/* Retries failed modbus read attempts for improved reliability. */
+static int rdtech_dps_read_holding_registers(struct sr_modbus_dev_inst *modbus,
+       int address, int nb_registers, uint16_t *registers)
 {
-       int i, ret;
+       size_t retries;
+       int ret;
 
-       i = 0;
-       do {
+       retries = 3;
+       while (retries--) {
                ret = sr_modbus_read_holding_registers(modbus,
                        address, nb_registers, registers);
-               ++i;
-       } while (ret != SR_OK && i < 3);
+               if (ret == SR_OK)
+                       return ret;
+       }
 
        return ret;
 }
 
-SR_PRIV int rdtech_dps_get_reg(const struct sr_dev_inst *sdi,
-               uint16_t address, uint16_t *value)
+/* Set one 16bit register. LE format for DPS devices. */
+static int rdtech_dps_set_reg(const struct sr_dev_inst *sdi,
+       uint16_t address, uint16_t value)
 {
        struct dev_context *devc;
        struct sr_modbus_dev_inst *modbus;
        uint16_t registers[1];
        int ret;
+       uint8_t *wrptr;
 
        devc = sdi->priv;
        modbus = sdi->conn;
 
+       wrptr = (void *)registers;
+       write_u16be(wrptr, value);
+
        g_mutex_lock(&devc->rw_mutex);
-       ret = rdtech_dps_read_holding_registers(modbus, address, 1, registers);
+       ret = sr_modbus_write_multiple_registers(modbus, address,
+               ARRAY_SIZE(registers), registers);
        g_mutex_unlock(&devc->rw_mutex);
-       *value = RB16(registers + 0);
+
        return ret;
 }
 
-SR_PRIV int rdtech_dps_set_reg(const struct sr_dev_inst *sdi,
-               uint16_t address, uint16_t value)
+/* Set one 16bit register. BE format for RD devices. */
+static int rdtech_rd_set_reg(const struct sr_dev_inst *sdi,
+       uint16_t address, uint16_t value)
 {
        struct dev_context *devc;
        struct sr_modbus_dev_inst *modbus;
        uint16_t registers[1];
        int ret;
+       uint8_t *wrptr;
 
        devc = sdi->priv;
        modbus = sdi->conn;
 
-       WB16(registers, value);
+       wrptr = (void *)registers;
+       write_u16be(wrptr, value);
+
        g_mutex_lock(&devc->rw_mutex);
-       ret = sr_modbus_write_multiple_registers(modbus, address, 1, registers);
+       ret = sr_modbus_write_multiple_registers(modbus, address,
+               ARRAY_SIZE(registers), registers);
        g_mutex_unlock(&devc->rw_mutex);
+
        return ret;
 }
 
+/* Get DPS model number and firmware version from a connected device. */
 SR_PRIV int rdtech_dps_get_model_version(struct sr_modbus_dev_inst *modbus,
-               uint16_t *model, uint16_t *version)
+       enum rdtech_dps_model_type model_type,
+       uint16_t *model, uint16_t *version, uint32_t *serno)
 {
-       uint16_t registers[2];
+       uint16_t registers[4];
        int ret;
+       const uint8_t *rdptr;
 
        /*
-        * No mutex here, because there is no sr_dev_inst when this function
-        * is called.
+        * No mutex here because when the routine executes then the
+        * device instance was not created yet (probe phase).
         */
-       ret = rdtech_dps_read_holding_registers(modbus, REG_MODEL, 2, registers);
-       if (ret == SR_OK) {
-               *model = RB16(registers + 0);
-               *version = RB16(registers + 1);
-               sr_info("RDTech PSU model: %d version: %d", *model, *version);
+       switch (model_type) {
+       case MODEL_DPS:
+               /* Get the MODEL and VERSION registers. */
+               ret = rdtech_dps_read_holding_registers(modbus,
+                       REG_DPS_MODEL, 2, registers);
+               if (ret != SR_OK)
+                       return ret;
+               rdptr = (void *)registers;
+               *model = read_u16be_inc(&rdptr);
+               *version = read_u16be_inc(&rdptr);
+               *serno = 0;
+               sr_info("RDTech DPS/DPH model: %u version: %u",
+                       *model, *version);
+               return SR_OK;
+       case MODEL_RD:
+               /* Get the MODEL, SERIAL, and FIRMWARE registers. */
+               ret = rdtech_dps_read_holding_registers(modbus,
+                       REG_RD_MODEL, 4, registers);
+               if (ret != SR_OK)
+                       return ret;
+               rdptr = (void *)registers;
+               *model = read_u16be_inc(&rdptr) / 10;
+               *serno = read_u32be_inc(&rdptr);
+               *version = read_u16be_inc(&rdptr);
+               sr_info("RDTech RD model: %u version: %u, serno %u",
+                       *model, *version, *serno);
+               return SR_OK;
+       default:
+               sr_err("Unexpected RDTech PSU device type. Programming error?");
+               return SR_ERR_ARG;
        }
-       return ret;
+       /* UNREACH */
 }
 
-static void send_value(const struct sr_dev_inst *sdi, struct sr_channel *ch,
-               float value, enum sr_mq mq, enum sr_mqflag mqflags,
-               enum sr_unit unit, int digits)
+/* Send a measured value to the session feed. */
+static int send_value(const struct sr_dev_inst *sdi,
+       struct sr_channel *ch, float value,
+       enum sr_mq mq, enum sr_mqflag mqflags,
+       enum sr_unit unit, int digits)
 {
        struct sr_datafeed_packet packet;
        struct sr_datafeed_analog analog;
        struct sr_analog_encoding encoding;
        struct sr_analog_meaning meaning;
        struct sr_analog_spec spec;
+       int ret;
 
        sr_analog_init(&analog, &encoding, &meaning, &spec, digits);
        analog.meaning->channels = g_slist_append(NULL, ch);
@@ -111,57 +236,442 @@ static void send_value(const struct sr_dev_inst *sdi, struct sr_channel *ch,
 
        packet.type = SR_DF_ANALOG;
        packet.payload = &analog;
-       sr_session_send(sdi, &packet);
+       ret = sr_session_send(sdi, &packet);
+
        g_slist_free(analog.meaning->channels);
+
+       return ret;
+}
+
+/*
+ * Get the device's current state. Exhaustively, relentlessly.
+ * Concentrate all details of communication in the physical transport,
+ * register layout interpretation, and potential model dependency in
+ * this central spot, to simplify maintenance.
+ *
+ * TODO Optionally limit the transfer volume depending on caller's spec
+ * which detail level is desired? Is 10 registers each 16bits an issue
+ * when the UART bitrate is only 9600bps?
+ */
+SR_PRIV int rdtech_dps_get_state(const struct sr_dev_inst *sdi,
+       struct rdtech_dps_state *state, enum rdtech_dps_state_context reason)
+{
+       struct dev_context *devc;
+       struct sr_modbus_dev_inst *modbus;
+       gboolean get_config, get_init_state, get_curr_meas;
+       uint16_t registers[12];
+       int ret;
+       const uint8_t *rdptr;
+       uint16_t uset_raw, iset_raw, uout_raw, iout_raw, power_raw;
+       uint16_t reg_val, reg_state, out_state, ovpset_raw, ocpset_raw;
+       gboolean is_lock, is_out_enabled, is_reg_cc;
+       gboolean uses_ovp, uses_ocp;
+       float volt_target, curr_limit;
+       float ovp_threshold, ocp_threshold;
+       float curr_voltage, curr_current, curr_power;
+
+       if (!sdi || !sdi->priv || !sdi->conn)
+               return SR_ERR_ARG;
+       devc = sdi->priv;
+       modbus = sdi->conn;
+       if (!state)
+               return SR_ERR_ARG;
+
+       /* Determine the requested level of response detail. */
+       get_config = FALSE;
+       get_init_state = FALSE;
+       get_curr_meas = FALSE;
+       switch (reason) {
+       case ST_CTX_CONFIG:
+               get_config = TRUE;
+               get_init_state = TRUE;
+               get_curr_meas = TRUE;
+               break;
+       case ST_CTX_PRE_ACQ:
+               get_init_state = TRUE;
+               get_curr_meas = TRUE;
+               break;
+       case ST_CTX_IN_ACQ:
+               get_curr_meas = TRUE;
+               break;
+       default:
+               /* EMPTY */
+               break;
+       }
+       /*
+        * TODO Make use of this information to reduce the transfer
+        * volume, especially on low bitrate serial connections. Though
+        * the device firmware's samplerate is probably more limiting
+        * than communication bandwidth is.
+        */
+       (void)get_config;
+       (void)get_init_state;
+       (void)get_curr_meas;
+
+       switch (devc->model->model_type) {
+       case MODEL_DPS:
+               /*
+                * Transfer a chunk of registers in a single call. It's
+                * unfortunate that the model dependency and the sparse
+                * register map force us to open code addresses, sizes,
+                * and the sequence of the registers and how to interpret
+                * their bit fields. But then this is not too unusual for
+                * a hardware specific device driver ...
+                */
+               g_mutex_lock(&devc->rw_mutex);
+               ret = rdtech_dps_read_holding_registers(modbus,
+                       REG_DPS_USET, 10, registers);
+               g_mutex_unlock(&devc->rw_mutex);
+               if (ret != SR_OK)
+                       return ret;
+
+               /* Interpret the registers' values. */
+               rdptr = (const void *)registers;
+               uset_raw = read_u16be_inc(&rdptr);
+               volt_target = uset_raw / devc->voltage_multiplier;
+               iset_raw = read_u16be_inc(&rdptr);
+               curr_limit = iset_raw / devc->current_multiplier;
+               uout_raw = read_u16be_inc(&rdptr);
+               curr_voltage = uout_raw / devc->voltage_multiplier;
+               iout_raw = read_u16be_inc(&rdptr);
+               curr_current = iout_raw / devc->current_multiplier;
+               power_raw = read_u16be_inc(&rdptr);
+               curr_power = power_raw / 100.0f;
+               (void)read_u16be_inc(&rdptr); /* UIN */
+               reg_val = read_u16be_inc(&rdptr); /* LOCK */
+               is_lock = reg_val != 0;
+               reg_val = read_u16be_inc(&rdptr); /* PROTECT */
+               uses_ovp = reg_val == STATE_OVP;
+               uses_ocp = reg_val == STATE_OCP;
+               reg_state = read_u16be_inc(&rdptr); /* CV_CC */
+               is_reg_cc = reg_state == MODE_CC;
+               out_state = read_u16be_inc(&rdptr); /* ENABLE */
+               is_out_enabled = out_state != 0;
+
+               /* Transfer another chunk of registers in a single call. */
+               g_mutex_lock(&devc->rw_mutex);
+               ret = rdtech_dps_read_holding_registers(modbus,
+                       PRE_DPS_OVPSET, 2, registers);
+               g_mutex_unlock(&devc->rw_mutex);
+               if (ret != SR_OK)
+                       return ret;
+
+               /* Interpret the second registers chunk's values. */
+               rdptr = (const void *)registers;
+               ovpset_raw = read_u16be_inc(&rdptr); /* PRE OVPSET */
+               ovp_threshold = ovpset_raw * devc->voltage_multiplier;
+               ocpset_raw = read_u16be_inc(&rdptr); /* PRE OCPSET */
+               ocp_threshold = ocpset_raw * devc->current_multiplier;
+
+               break;
+
+       case MODEL_RD:
+               /* Retrieve a set of adjacent registers. */
+               g_mutex_lock(&devc->rw_mutex);
+               ret = rdtech_dps_read_holding_registers(modbus,
+                       REG_RD_VOLT_TGT, 11, registers);
+               g_mutex_unlock(&devc->rw_mutex);
+               if (ret != SR_OK)
+                       return ret;
+
+               /* Interpret the registers' raw content. */
+               rdptr = (const void *)registers;
+               uset_raw = read_u16be_inc(&rdptr); /* USET */
+               volt_target = uset_raw / devc->voltage_multiplier;
+               iset_raw = read_u16be_inc(&rdptr); /* ISET */
+               curr_limit = iset_raw / devc->current_multiplier;
+               uout_raw = read_u16be_inc(&rdptr); /* UOUT */
+               curr_voltage = uout_raw / devc->voltage_multiplier;
+               iout_raw = read_u16be_inc(&rdptr); /* IOUT */
+               curr_current = iout_raw / devc->current_multiplier;
+               (void)read_u16be_inc(&rdptr); /* ENERGY */
+               power_raw = read_u16be_inc(&rdptr); /* POWER */
+               curr_power = power_raw / 100.0f;
+               (void)read_u16be_inc(&rdptr); /* VOLT_IN */
+               (void)read_u16be_inc(&rdptr);
+               reg_val = read_u16be_inc(&rdptr); /* PROTECT */
+               uses_ovp = reg_val == STATE_OVP;
+               uses_ocp = reg_val == STATE_OCP;
+               reg_state = read_u16be_inc(&rdptr); /* REGULATION */
+               is_reg_cc = reg_state == MODE_CC;
+               out_state = read_u16be_inc(&rdptr); /* ENABLE */
+               is_out_enabled = out_state != 0;
+
+               /* Retrieve a set of adjacent registers. */
+               g_mutex_lock(&devc->rw_mutex);
+               ret = rdtech_dps_read_holding_registers(modbus,
+                       REG_RD_OVP_THR, 2, registers);
+               g_mutex_unlock(&devc->rw_mutex);
+               if (ret != SR_OK)
+                       return ret;
+
+               /* Interpret the registers' raw content. */
+               rdptr = (const void *)registers;
+               ovpset_raw = read_u16be_inc(&rdptr); /* OVP THR */
+               ovp_threshold = ovpset_raw / devc->voltage_multiplier;
+               ocpset_raw = read_u16be_inc(&rdptr); /* OCP THR */
+               ocp_threshold = ocpset_raw / devc->current_multiplier;
+
+               /* Details which we cannot query from the device. */
+               is_lock = FALSE;
+
+               break;
+
+       default:
+               /* ShouldNotHappen(TM). Probe should have failed. */
+               return SR_ERR_ARG;
+       }
+
+       /*
+        * Store gathered details in the high level container.
+        *
+        * TODO Make use of the caller's context. The register access
+        * code path above need not have gathered every detail in every
+        * invocation.
+        */
+       memset(state, 0, sizeof(*state));
+       state->lock = is_lock;
+       state->mask |= STATE_LOCK;
+       state->output_enabled = is_out_enabled;
+       state->mask |= STATE_OUTPUT_ENABLED;
+       state->regulation_cc = is_reg_cc;
+       state->mask |= STATE_REGULATION_CC;
+       state->protect_ovp = uses_ovp;
+       state->mask |= STATE_PROTECT_OVP;
+       state->protect_ocp = uses_ocp;
+       state->mask |= STATE_PROTECT_OCP;
+       state->protect_enabled = TRUE;
+       state->mask |= STATE_PROTECT_ENABLED;
+       state->voltage_target = volt_target;
+       state->mask |= STATE_VOLTAGE_TARGET;
+       state->current_limit = curr_limit;
+       state->mask |= STATE_CURRENT_LIMIT;
+       state->ovp_threshold = ovp_threshold;
+       state->mask |= STATE_OVP_THRESHOLD;
+       state->ocp_threshold = ocp_threshold;
+       state->mask |= STATE_OCP_THRESHOLD;
+       state->voltage = curr_voltage;
+       state->mask |= STATE_VOLTAGE;
+       state->current = curr_current;
+       state->mask |= STATE_CURRENT;
+       state->power = curr_power;
+       state->mask |= STATE_POWER;
+
+       return SR_OK;
+}
+
+/* Setup device's parameters. Selectively, from caller specs. */
+SR_PRIV int rdtech_dps_set_state(const struct sr_dev_inst *sdi,
+       struct rdtech_dps_state *state)
+{
+       struct dev_context *devc;
+       uint16_t reg_value;
+       int ret;
+
+       if (!sdi || !sdi->priv || !sdi->conn)
+               return SR_ERR_ARG;
+       devc = sdi->priv;
+       if (!state)
+               return SR_ERR_ARG;
+
+       /* Only a subset of known values is settable. */
+       if (state->mask & STATE_OUTPUT_ENABLED) {
+               reg_value = state->output_enabled ? 1 : 0;
+               switch (devc->model->model_type) {
+               case MODEL_DPS:
+                       ret = rdtech_dps_set_reg(sdi, REG_DPS_ENABLE, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               case MODEL_RD:
+                       ret = rdtech_rd_set_reg(sdi, REG_RD_ENABLE, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               default:
+                       return SR_ERR_ARG;
+               }
+       }
+       if (state->mask & STATE_VOLTAGE_TARGET) {
+               reg_value = state->voltage_target * devc->voltage_multiplier;
+               switch (devc->model->model_type) {
+               case MODEL_DPS:
+                       ret = rdtech_dps_set_reg(sdi, REG_DPS_USET, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               case MODEL_RD:
+                       ret = rdtech_rd_set_reg(sdi, REG_RD_VOLT_TGT, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               default:
+                       return SR_ERR_ARG;
+               }
+       }
+       if (state->mask & STATE_CURRENT_LIMIT) {
+               reg_value = state->current_limit * devc->current_multiplier;
+               switch (devc->model->model_type) {
+               case MODEL_DPS:
+                       ret = rdtech_dps_set_reg(sdi, REG_DPS_ISET, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               case MODEL_RD:
+                       ret = rdtech_rd_set_reg(sdi, REG_RD_CURR_LIM, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               default:
+                       return SR_ERR_ARG;
+               }
+       }
+       if (state->mask & STATE_OVP_THRESHOLD) {
+               reg_value = state->ovp_threshold * devc->voltage_multiplier;
+               switch (devc->model->model_type) {
+               case MODEL_DPS:
+                       ret = rdtech_dps_set_reg(sdi, PRE_DPS_OVPSET, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               case MODEL_RD:
+                       ret = rdtech_rd_set_reg(sdi, REG_RD_OVP_THR, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               default:
+                       return SR_ERR_ARG;
+               }
+       }
+       if (state->mask & STATE_OCP_THRESHOLD) {
+               reg_value = state->ocp_threshold * devc->current_multiplier;
+               switch (devc->model->model_type) {
+               case MODEL_DPS:
+                       ret = rdtech_dps_set_reg(sdi, PRE_DPS_OCPSET, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               case MODEL_RD:
+                       ret = rdtech_rd_set_reg(sdi, REG_RD_OCP_THR, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               default:
+                       return SR_ERR_ARG;
+               }
+       }
+       if (state->mask & STATE_LOCK) {
+               switch (devc->model->model_type) {
+               case MODEL_DPS:
+                       reg_value = state->lock ? 1 : 0;
+                       ret = rdtech_dps_set_reg(sdi, REG_DPS_LOCK, reg_value);
+                       if (ret != SR_OK)
+                               return ret;
+                       break;
+               case MODEL_RD:
+                       /* Do nothing, _and_ silently succeed. */
+                       break;
+               default:
+                       return SR_ERR_ARG;
+               }
+       }
+
+       return SR_OK;
+}
+
+/* Get the current state when acquisition starts. */
+SR_PRIV int rdtech_dps_seed_receive(const struct sr_dev_inst *sdi)
+{
+       struct dev_context *devc;
+       struct rdtech_dps_state state;
+       int ret;
+
+       if (!sdi || !sdi->priv)
+               return SR_ERR_ARG;
+       devc = sdi->priv;
+
+       ret = rdtech_dps_get_state(sdi, &state, ST_CTX_PRE_ACQ);
+       if (ret != SR_OK)
+               return ret;
+
+       if (state.mask & STATE_PROTECT_OVP)
+               devc->curr_ovp_state = state.protect_ovp;
+       if (state.mask & STATE_PROTECT_OCP)
+               devc->curr_ocp_state = state.protect_ocp;
+       if (state.mask & STATE_REGULATION_CC)
+               devc->curr_cc_state = state.regulation_cc;
+       if (state.mask & STATE_OUTPUT_ENABLED)
+               devc->curr_out_state = state.output_enabled;
+
+       return SR_OK;
 }
 
+/* Get measurements, track state changes during acquisition. */
 SR_PRIV int rdtech_dps_receive_data(int fd, int revents, void *cb_data)
 {
        struct sr_dev_inst *sdi;
        struct dev_context *devc;
-       struct sr_modbus_dev_inst *modbus;
-       struct sr_datafeed_packet packet;
-       uint16_t registers[3];
+       struct rdtech_dps_state state;
        int ret;
+       struct sr_channel *ch;
+       const char *regulation_text;
 
        (void)fd;
        (void)revents;
 
-       if (!(sdi = cb_data))
+       sdi = cb_data;
+       if (!sdi)
                return TRUE;
-
-       modbus = sdi->conn;
        devc = sdi->priv;
 
-       g_mutex_lock(&devc->rw_mutex);
-       /*
-        * Using the libsigrok function here, because it doesn't matter if the
-        * reading fails. It will be done again in the next acquision cycle anyways.
-        */
-       ret = sr_modbus_read_holding_registers(modbus, REG_UOUT, 3, registers);
-       g_mutex_unlock(&devc->rw_mutex);
+       /* Get the device's current state. */
+       ret = rdtech_dps_get_state(sdi, &state, ST_CTX_IN_ACQ);
+       if (ret != SR_OK)
+               return ret;
+
+
+       /* Submit measurement data to the session feed. */
+       std_session_send_df_frame_begin(sdi);
+       ch = g_slist_nth_data(sdi->channels, 0);
+       send_value(sdi, ch, state.voltage,
+               SR_MQ_VOLTAGE, SR_MQFLAG_DC, SR_UNIT_VOLT,
+               devc->model->voltage_digits);
+       ch = g_slist_nth_data(sdi->channels, 1);
+       send_value(sdi, ch, state.current,
+               SR_MQ_CURRENT, SR_MQFLAG_DC, SR_UNIT_AMPERE,
+               devc->model->current_digits);
+       ch = g_slist_nth_data(sdi->channels, 2);
+       send_value(sdi, ch, state.power,
+               SR_MQ_POWER, 0, SR_UNIT_WATT, 2);
+       std_session_send_df_frame_end(sdi);
 
-       if (ret == SR_OK) {
-               packet.type = SR_DF_FRAME_BEGIN;
-               sr_session_send(sdi, &packet);
-
-               send_value(sdi, sdi->channels->data,
-                       RB16(registers + 0) / devc->voltage_multiplier,
-                       SR_MQ_VOLTAGE, SR_MQFLAG_DC, SR_UNIT_VOLT,
-                       devc->model->voltage_digits);
-               send_value(sdi, sdi->channels->next->data,
-                       RB16(registers + 1) / devc->current_multiplier,
-                       SR_MQ_CURRENT, SR_MQFLAG_DC, SR_UNIT_AMPERE,
-                       devc->model->current_digits);
-               send_value(sdi, sdi->channels->next->next->data,
-                       RB16(registers + 2) / 100.0f,
-                       SR_MQ_POWER, 0, SR_UNIT_WATT, 2);
-
-               packet.type = SR_DF_FRAME_END;
-               sr_session_send(sdi, &packet);
-               sr_sw_limits_update_samples_read(&devc->limits, 1);
+       /* Check for state changes. */
+       if (devc->curr_ovp_state != state.protect_ovp) {
+               (void)sr_session_send_meta(sdi,
+                       SR_CONF_OVER_VOLTAGE_PROTECTION_ACTIVE,
+                       g_variant_new_boolean(state.protect_ovp));
+               devc->curr_ovp_state = state.protect_ovp;
+       }
+       if (devc->curr_ocp_state != state.protect_ocp) {
+               (void)sr_session_send_meta(sdi,
+                       SR_CONF_OVER_CURRENT_PROTECTION_ACTIVE,
+                       g_variant_new_boolean(state.protect_ocp));
+               devc->curr_ocp_state = state.protect_ocp;
+       }
+       if (devc->curr_cc_state != state.regulation_cc) {
+               regulation_text = state.regulation_cc ? "CC" : "CV";
+               (void)sr_session_send_meta(sdi, SR_CONF_REGULATION,
+                       g_variant_new_string(regulation_text));
+               devc->curr_cc_state = state.regulation_cc;
+       }
+       if (devc->curr_out_state != state.output_enabled) {
+               (void)sr_session_send_meta(sdi, SR_CONF_ENABLED,
+                       g_variant_new_boolean(state.output_enabled));
+               devc->curr_out_state = state.output_enabled;
        }
 
+       /* Check optional acquisition limits. */
+       sr_sw_limits_update_samples_read(&devc->limits, 1);
        if (sr_sw_limits_check(&devc->limits)) {
                sr_dev_acquisition_stop(sdi);
                return TRUE;