From: Frank Stettner <redacted>
Date: Mon, 2 Oct 2017 10:50:04 +0000 (+0200)
Subject: hp-3478a: Initial HP 3478A diver
X-Git-Url: https://sigrok.org/gitaction?a=commitdiff_plain;h=d2c1730a281ed4982f2ea8be0cd137d0e47135a0;p=libsigrok.git

hp-3478a: Initial HP 3478A diver
---

diff --git a/configure.ac b/configure.ac
index e01d7200..8299e4d0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -244,7 +244,7 @@ SR_DRIVER([Hantek 4032L], [hantek-4032l], [libusb])
 SR_DRIVER([Hantek 6xxx], [hantek-6xxx], [libusb])
 SR_DRIVER([Hantek DSO], [hantek-dso], [libusb])
 SR_DRIVER([HP 3457A], [hp-3457a])
-SR_DRIVER([HP 3478A], [hp-3478a])
+SR_DRIVER([HP 3478A], [hp-3478a], [libgpib])
 SR_DRIVER([Hung-Chang DSO-2100], [hung-chang-dso-2100], [libieee1284])
 SR_DRIVER([Ikalogic Scanalogic-2], [ikalogic-scanalogic2], [libusb])
 SR_DRIVER([Ikalogic Scanaplus], [ikalogic-scanaplus], [libftdi])
diff --git a/src/hardware/hp-3478a/api.c b/src/hardware/hp-3478a/api.c
index b97a21e0..84db3180 100644
--- a/src/hardware/hp-3478a/api.c
+++ b/src/hardware/hp-3478a/api.c
@@ -18,39 +18,109 @@
  */
 
 #include <config.h>
+#include "scpi.h"
 #include "protocol.h"
 
-static GSList *scan(struct sr_dev_driver *di, GSList *options)
+static const uint32_t scanopts[] = {
+	SR_CONF_CONN,
+};
+
+static const uint32_t drvopts[] = {
+	SR_CONF_MULTIMETER,
+};
+
+static const uint32_t devopts[] = {
+	SR_CONF_CONTINUOUS,
+	SR_CONF_LIMIT_SAMPLES | SR_CONF_GET | SR_CONF_SET,
+	SR_CONF_LIMIT_MSEC | SR_CONF_GET | SR_CONF_SET,
+	SR_CONF_MEASURED_QUANTITY | SR_CONF_GET | SR_CONF_SET | SR_CONF_LIST,
+};
+
+static const struct {
+	enum sr_mq mq;
+	enum sr_mqflag mqflag;
+} mqopts[] = {
+	{SR_MQ_VOLTAGE, SR_MQFLAG_DC},
+	{SR_MQ_VOLTAGE, SR_MQFLAG_DC | SR_MQFLAG_AUTORANGE},
+	{SR_MQ_VOLTAGE, SR_MQFLAG_AC | SR_MQFLAG_RMS},
+	{SR_MQ_VOLTAGE, SR_MQFLAG_AC | SR_MQFLAG_RMS | SR_MQFLAG_AUTORANGE},
+	{SR_MQ_CURRENT, SR_MQFLAG_DC},
+	{SR_MQ_CURRENT, SR_MQFLAG_DC | SR_MQFLAG_AUTORANGE},
+	{SR_MQ_CURRENT, SR_MQFLAG_AC | SR_MQFLAG_RMS},
+	{SR_MQ_CURRENT, SR_MQFLAG_AC | SR_MQFLAG_RMS | SR_MQFLAG_AUTORANGE},
+	{SR_MQ_RESISTANCE, 0},
+	{SR_MQ_RESISTANCE, 0 | SR_MQFLAG_AUTORANGE},
+	{SR_MQ_RESISTANCE, SR_MQFLAG_FOUR_WIRE},
+	{SR_MQ_RESISTANCE, SR_MQFLAG_FOUR_WIRE | SR_MQFLAG_AUTORANGE},
+};
+
+SR_PRIV struct sr_dev_driver hp_3478a_driver_info;
+
+static int create_front_channel(struct sr_dev_inst *sdi, int chan_idx)
 {
-	struct drv_context *drvc;
-	GSList *devices;
+	struct sr_channel *channel;
+	struct channel_context *chanc;
 
-	(void)options;
+	chanc = g_malloc(sizeof(*chanc));
+	chanc->location = TERMINAL_FRONT;
 
-	devices = NULL;
-	drvc = di->context;
-	drvc->instances = NULL;
+	channel = sr_channel_new(sdi, chan_idx++, SR_CHANNEL_ANALOG, TRUE, "P1");
+	channel->priv = chanc;
 
-	/* TODO: scan for devices, either based on a SR_CONF_CONN option
-	 * or on a USB scan. */
+	return chan_idx;
+}
 
-	return devices;
+static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
+{
+	int ret;
+	struct sr_dev_inst *sdi;
+	struct dev_context *devc;
+
+	sdi = g_malloc0(sizeof(struct sr_dev_inst));
+	sdi->vendor = g_strdup("Hewlett-Packard");
+	sdi->model = g_strdup("3478A");
+	sdi->conn = scpi;
+	sdi->driver = &hp_3478a_driver_info;
+	sdi->inst_type = SR_INST_SCPI;
+
+	devc = g_malloc0(sizeof(struct dev_context));
+	sr_sw_limits_init(&devc->limits);
+	sdi->priv = devc;
+
+	/* Get actual status (function, digits, ...). */
+	ret = hp_3478a_get_status_bytes(sdi);
+	if (ret != SR_OK)
+		return NULL;
+
+	create_front_channel(sdi, 0);
+
+	return sdi;
+}
+
+static GSList *scan(struct sr_dev_driver *di, GSList *options)
+{
+	return sr_scpi_scan(di->context, options, probe_device);
 }
 
 static int dev_open(struct sr_dev_inst *sdi)
 {
-	(void)sdi;
+	struct sr_scpi_dev_inst *scpi;
+
+	scpi = sdi->conn;
 
-	/* TODO: get handle from sdi->conn and open it. */
+	if (sr_scpi_open(scpi) != SR_OK)
+		return SR_ERR;
 
 	return SR_OK;
 }
 
 static int dev_close(struct sr_dev_inst *sdi)
 {
-	(void)sdi;
+	struct sr_scpi_dev_inst *scpi;
+
+	scpi = sdi->conn;
 
-	/* TODO: get handle from sdi->conn and close it. */
+	sr_scpi_close(scpi);
 
 	return SR_OK;
 }
@@ -58,75 +128,140 @@ static int dev_close(struct sr_dev_inst *sdi)
 static int config_get(uint32_t key, GVariant **data,
 	const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 {
+	struct dev_context *devc;
 	int ret;
+	GVariant *arr[2];
 
-	(void)sdi;
-	(void)data;
 	(void)cg;
 
-	ret = SR_OK;
+	devc = sdi->priv;
+
 	switch (key) {
-	/* TODO */
+	case SR_CONF_LIMIT_SAMPLES:
+	case SR_CONF_LIMIT_MSEC:
+		return sr_sw_limits_config_get(&devc->limits, key, data);
+	case SR_CONF_MEASURED_QUANTITY:
+		ret = hp_3478a_get_status_bytes(sdi);
+		if (ret != SR_OK)
+			return ret;
+		arr[0] = g_variant_new_uint32(devc->measurement_mq);
+		arr[1] = g_variant_new_uint64(devc->measurement_mq_flags);
+		*data = g_variant_new_tuple(arr, 2);
+		break;
 	default:
 		return SR_ERR_NA;
 	}
 
-	return ret;
+	return SR_OK;
 }
 
 static int config_set(uint32_t key, GVariant *data,
 	const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 {
-	int ret;
+	struct dev_context *devc;
+	enum sr_mq mq;
+	enum sr_mqflag mq_flags;
+	GVariant *tuple_child;
 
-	(void)sdi;
-	(void)data;
 	(void)cg;
 
-	ret = SR_OK;
+	devc = sdi->priv;
+
 	switch (key) {
-	/* TODO */
+	case SR_CONF_LIMIT_SAMPLES:
+	case SR_CONF_LIMIT_MSEC:
+		return sr_sw_limits_config_set(&devc->limits, key, data);
+	case SR_CONF_MEASURED_QUANTITY:
+		tuple_child = g_variant_get_child_value(data, 0);
+		mq = g_variant_get_uint32(tuple_child);
+		tuple_child = g_variant_get_child_value(data, 1);
+		mq_flags = g_variant_get_uint64(tuple_child);
+		g_variant_unref(tuple_child);
+		return hp_3478a_set_mq(sdi, mq, mq_flags);
 	default:
-		ret = SR_ERR_NA;
+		return SR_ERR_NA;
 	}
 
-	return ret;
+	return SR_OK;
 }
 
 static int config_list(uint32_t key, GVariant **data,
 	const struct sr_dev_inst *sdi, const struct sr_channel_group *cg)
 {
-	int ret;
+	unsigned int i;
+	GVariant *gvar, *arr[2];
+	GVariantBuilder gvb;
 
-	(void)sdi;
-	(void)data;
-	(void)cg;
-
-	ret = SR_OK;
 	switch (key) {
-	/* TODO */
+	case SR_CONF_SCAN_OPTIONS:
+	case SR_CONF_DEVICE_OPTIONS:
+		return STD_CONFIG_LIST(key, data, sdi, cg, scanopts, drvopts, devopts);
+	case SR_CONF_MEASURED_QUANTITY:
+		/*
+		 * TODO: move to std.c as
+		 *       SR_PRIV GVariant *std_gvar_measured_quantities()
+		 */
+		g_variant_builder_init(&gvb, G_VARIANT_TYPE_ARRAY);
+		for (i = 0; i < ARRAY_SIZE(mqopts); i++) {
+			arr[0] = g_variant_new_uint32(mqopts[i].mq);
+			arr[1] = g_variant_new_uint64(mqopts[i].mqflag);
+			gvar = g_variant_new_tuple(arr, 2);
+			g_variant_builder_add_value(&gvb, gvar);
+		}
+		*data = g_variant_builder_end(&gvb);
+		break;
 	default:
 		return SR_ERR_NA;
 	}
 
-	return ret;
+	return SR_OK;
 }
 
 static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 {
-	/* TODO: configure hardware, reset acquisition state, set up
-	 * callbacks and send header packet. */
+	int ret;
+	struct sr_scpi_dev_inst *scpi;
+	struct dev_context *devc;
+
+	scpi = sdi->conn;
+	devc = sdi->priv;
 
-	(void)sdi;
+	sr_sw_limits_acquisition_start(&devc->limits);
+	std_session_send_df_header(sdi);
+
+	/*
+	 * NOTE: For faster readings, there are some things one can do:
+	 *     - Turn off the display: sr_scpi_send(scpi, "D3SIGROK").
+	 *     - Set the line frequency to 60Hz via switch (back of the unit).
+	 *     - Set to 3.5 digits measurement (add config key SR_CONF_DIGITS).
+	 */
+
+	/* Set to internal trigger. */
+	sr_scpi_send(scpi, "T1");
+	/* Get device status. */
+	hp_3478a_get_status_bytes(sdi);
+
+	ret = sr_scpi_source_add(sdi->session, scpi, G_IO_IN, 100,
+			hp_3478a_receive_data, (void *)sdi);
+	if (ret != SR_OK)
+		return ret;
 
 	return SR_OK;
 }
 
 static int dev_acquisition_stop(struct sr_dev_inst *sdi)
 {
-	/* TODO: stop acquisition. */
+	struct sr_scpi_dev_inst *scpi;
+
+	scpi = sdi->conn;
+
+	sr_scpi_source_remove(sdi->session, scpi);
+	std_session_send_df_end(sdi);
 
-	(void)sdi;
+	/* Set to internal trigger. */
+	sr_scpi_send(scpi, "T1");
+	/* Turn on display. */
+	sr_scpi_send(scpi, "D1");
 
 	return SR_OK;
 }
diff --git a/src/hardware/hp-3478a/protocol.c b/src/hardware/hp-3478a/protocol.c
index a794d562..e9cf6677 100644
--- a/src/hardware/hp-3478a/protocol.c
+++ b/src/hardware/hp-3478a/protocol.c
@@ -1,7 +1,7 @@
 /*
  * This file is part of the libsigrok project.
  *
- * Copyright (C) 2017 Frank Stettner <frank-stettner@gmx.net>
+ * Copyright (C) 2017-2018 Frank Stettner <frank-stettner@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
@@ -18,24 +18,448 @@
  */
 
 #include <config.h>
+#include <math.h>
+#include <stdlib.h>
+#include "scpi.h"
 #include "protocol.h"
 
+static int set_mq_volt(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags);
+static int set_mq_amp(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags);
+static int set_mq_ohm(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags);
+
+static const struct {
+	enum sr_mq mq;
+	int (*set_mode)(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags);
+} sr_mq_to_cmd_map[] = {
+	{ SR_MQ_VOLTAGE, set_mq_volt },
+	{ SR_MQ_CURRENT, set_mq_amp },
+	{ SR_MQ_RESISTANCE, set_mq_ohm },
+};
+
+static int set_mq_volt(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags)
+{
+	const char *cmd;
+
+	if ((flags & SR_MQFLAG_AC) != SR_MQFLAG_AC &&
+		(flags & SR_MQFLAG_DC) != SR_MQFLAG_DC)
+		return SR_ERR_NA;
+
+	if ((flags & SR_MQFLAG_AC) == SR_MQFLAG_AC)
+		cmd = "F2";
+	else
+		cmd = "F1";
+
+	return sr_scpi_send(scpi, "%s", cmd);
+}
+
+static int set_mq_amp(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags)
+{
+	const char *cmd;
+
+	if ((flags & SR_MQFLAG_AC) != SR_MQFLAG_AC &&
+		(flags & SR_MQFLAG_DC) != SR_MQFLAG_DC)
+		return SR_ERR_NA;
+
+	if (flags & SR_MQFLAG_AC)
+		cmd = "F6";
+	else
+		cmd = "F5";
+
+	return sr_scpi_send(scpi, "%s", cmd);
+}
+
+static int set_mq_ohm(struct sr_scpi_dev_inst *scpi, enum sr_mqflag flags)
+{
+	const char *cmd;
+
+	if (flags & SR_MQFLAG_FOUR_WIRE)
+		cmd = "F4";
+	else
+		cmd = "F3";
+
+	return sr_scpi_send(scpi, "%s", cmd);
+}
+
+SR_PRIV int hp_3478a_set_mq(const struct sr_dev_inst *sdi, enum sr_mq mq,
+				enum sr_mqflag mq_flags)
+{
+	int ret;
+	size_t i;
+	struct sr_scpi_dev_inst *scpi = sdi->conn;
+	struct dev_context *devc = sdi->priv;
+
+	/* No need to send command if we're not changing measurement type. */
+	if (devc->measurement_mq == mq &&
+		((devc->measurement_mq_flags & mq_flags) == mq_flags))
+		return SR_OK;
+
+	for (i = 0; i < ARRAY_SIZE(sr_mq_to_cmd_map); i++) {
+		if (sr_mq_to_cmd_map[i].mq != mq)
+			continue;
+
+		ret = sr_mq_to_cmd_map[i].set_mode(scpi, mq_flags);
+		if (ret != SR_OK)
+			return ret;
+
+		ret = hp_3478a_get_status_bytes(sdi);
+		return ret;
+	}
+
+	return SR_ERR_NA;
+}
+
+static int parse_range_vdc(struct dev_context *devc, uint8_t range_byte)
+{
+	if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VDC_30MV) {
+		devc->enc_digits = devc->spec_digits - 2;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VDC_300MV) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VDC_3V) {
+		devc->enc_digits = devc->spec_digits - 1;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VDC_30V) {
+		devc->enc_digits = devc->spec_digits - 2;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VDC_300V) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else {
+		return SR_ERR_DATA;
+	}
+
+	return SR_OK;
+}
+
+static int parse_range_vac(struct dev_context *devc, uint8_t range_byte)
+{
+	if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VAC_300MV) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VAC_3V) {
+		devc->enc_digits = devc->spec_digits - 1;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VAC_30V) {
+		devc->enc_digits = devc->spec_digits - 2;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_VAC_300V) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else {
+		return SR_ERR_DATA;
+	}
+
+	return SR_OK;
+}
+
+static int parse_range_a(struct dev_context *devc, uint8_t range_byte)
+{
+	if ((range_byte & SB1_RANGE_BLOCK) == RANGE_A_300MA) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_A_3A) {
+		devc->enc_digits = devc->spec_digits - 1;
+	} else {
+		return SR_ERR_DATA;
+	}
+
+	return SR_OK;
+}
+
+static int parse_range_ohm(struct dev_context *devc, uint8_t range_byte)
+{
+	if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_30R) {
+		devc->enc_digits = devc->spec_digits - 2;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_300R) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_3KR) {
+		devc->enc_digits = devc->spec_digits - 1;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_30KR) {
+		devc->enc_digits = devc->spec_digits - 2;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_300KR) {
+		devc->enc_digits = devc->spec_digits - 3;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_3MR) {
+		devc->enc_digits = devc->spec_digits - 1;
+	} else if ((range_byte & SB1_RANGE_BLOCK) == RANGE_OHM_30MR) {
+		devc->enc_digits = devc->spec_digits - 2;
+	} else {
+		return SR_ERR_DATA;
+	}
+
+	return SR_OK;
+}
+
+static int parse_function_byte(struct dev_context *devc, uint8_t function_byte)
+{
+	devc->measurement_mq_flags = 0;
+
+	/* Function + Range */
+	if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_VDC) {
+		devc->measurement_mq = SR_MQ_VOLTAGE;
+		devc->measurement_mq_flags |= SR_MQFLAG_DC;
+		devc->measurement_unit = SR_UNIT_VOLT;
+		parse_range_vdc(devc, function_byte);
+	} else if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_VAC) {
+		devc->measurement_mq = SR_MQ_VOLTAGE;
+		devc->measurement_mq_flags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
+		devc->measurement_unit = SR_UNIT_VOLT;
+		parse_range_vac(devc, function_byte);
+	} else if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_2WR) {
+		devc->measurement_mq = SR_MQ_RESISTANCE;
+		devc->measurement_unit = SR_UNIT_OHM;
+		parse_range_ohm(devc, function_byte);
+	} else if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_4WR) {
+		devc->measurement_mq = SR_MQ_RESISTANCE;
+		devc->measurement_mq_flags |= SR_MQFLAG_FOUR_WIRE;
+		devc->measurement_unit = SR_UNIT_OHM;
+		parse_range_ohm(devc, function_byte);
+	} else if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_ADC) {
+		devc->measurement_mq = SR_MQ_CURRENT;
+		devc->measurement_mq_flags |= SR_MQFLAG_DC;
+		devc->measurement_unit = SR_UNIT_AMPERE;
+		parse_range_a(devc, function_byte);
+	} else if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_AAC) {
+		devc->measurement_mq = SR_MQ_CURRENT;
+		devc->measurement_mq_flags |= SR_MQFLAG_AC | SR_MQFLAG_RMS;
+		devc->measurement_unit = SR_UNIT_AMPERE;
+		parse_range_a(devc, function_byte);
+	} else if ((function_byte & SB1_FUNCTION_BLOCK) == FUNCTION_EXR) {
+		devc->measurement_mq = SR_MQ_RESISTANCE;
+		devc->measurement_unit = SR_UNIT_OHM;
+		parse_range_ohm(devc, function_byte);
+	}
+
+	/* Digits / Resolution */
+	if ((function_byte & SB1_DIGITS_BLOCK) == DIGITS_5_5) {
+		devc->spec_digits = 5;
+	} else if ((function_byte & SB1_DIGITS_BLOCK) == DIGITS_4_5) {
+		devc->spec_digits = 4;
+	} else if ((function_byte & SB1_DIGITS_BLOCK) == DIGITS_3_5) {
+		devc->spec_digits = 3;
+	}
+
+	return SR_OK;
+}
+
+static int parse_status_byte(struct dev_context *devc, uint8_t status_byte)
+{
+	devc->trigger = TRIGGER_UNDEFINED;
+
+	/* External Trigger */
+	if ((status_byte & STATUS_EXT_TRIGGER) == STATUS_EXT_TRIGGER)
+		devc->trigger = TRIGGER_EXTERNAL;
+
+	/* Cal RAM */
+	if ((status_byte & STATUS_CAL_RAM) == STATUS_CAL_RAM)
+		devc->calibration = TRUE;
+	else
+		devc->calibration = FALSE;
+
+	/* Front/Rear terminals */
+	if ((status_byte & STATUS_FRONT_TERMINAL) == STATUS_FRONT_TERMINAL)
+		devc->terminal = TERMINAL_FRONT;
+	else
+		devc->terminal = TERMINAL_REAR;
+
+	/* 50Hz / 60Hz */
+	if ((status_byte & STATUS_50HZ) == STATUS_50HZ)
+		devc->line = LINE_50HZ;
+	else
+		devc->line = LINE_60HZ;
+
+	/* Auto-Zero */
+	if ((status_byte & STATUS_AUTO_ZERO) == STATUS_AUTO_ZERO)
+		devc->auto_zero = TRUE;
+	else
+		devc->auto_zero = FALSE;
+
+	/* Auto-Range */
+	if ((status_byte & STATUS_AUTO_RANGE) == STATUS_AUTO_RANGE)
+		devc->measurement_mq_flags |= SR_MQFLAG_AUTORANGE;
+	else
+		devc->measurement_mq_flags &= ~SR_MQFLAG_AUTORANGE;
+
+	/* Internal trigger */
+	if ((status_byte & STATUS_INT_TRIGGER) == STATUS_INT_TRIGGER)
+		devc->trigger = TRIGGER_INTERNAL;
+
+	return SR_OK;
+}
+
+static int parse_srq_byte(uint8_t sqr_byte)
+{
+	(void)sqr_byte;
+
+#if 0
+	/* The ServiceReQuest register isn't used at the moment. */
+
+	/* PON SRQ */
+	if ((sqr_byte & SRQ_POWER_ON) == SRQ_POWER_ON)
+		sr_spew("hp_3478a_get_status_bytes: Power On SRQ or clear "
+				"msg received");
+
+	/* Cal failed SRQ */
+	if ((sqr_byte & SRQ_CAL_FAILED) == SRQ_CAL_FAILED)
+		sr_spew("hp_3478a_get_status_bytes: CAL failed SRQ");
+
+	/* Keyboard SRQ */
+	if ((sqr_byte & SRQ_KEYBORD) == SRQ_KEYBORD)
+		sr_spew("hp_3478a_get_status_bytes: Keyboard SRQ");
+
+	/* Hardware error SRQ */
+	if ((sqr_byte & SRQ_HARDWARE_ERR) == SRQ_HARDWARE_ERR)
+		sr_spew("hp_3478a_get_status_bytes: Hardware error SRQ");
+
+	/* Syntax error SRQ */
+	if ((sqr_byte & SRQ_SYNTAX_ERR) == SRQ_SYNTAX_ERR)
+		sr_spew("hp_3478a_get_status_bytes: Syntax error SRQ");
+
+	/* Every reading is available to the bus SRQ */
+	if ((sqr_byte & SRQ_BUS_AVAIL) == SRQ_BUS_AVAIL)
+		sr_spew("hp_3478a_get_status_bytes: Every reading is available to "
+				"the bus SRQ");
+#endif
+
+	return SR_OK;
+}
+
+static int parse_error_byte(uint8_t error_byte)
+{
+	int ret;
+
+	ret = SR_OK;
+
+	/* A/D link */
+	if ((error_byte & ERROR_AD_LINK) == ERROR_AD_LINK) {
+		sr_err("hp_3478a: Failure in the A/D link");
+		ret = SR_ERR;
+	}
+
+	/* A/D Self Test */
+	if ((error_byte & ERROR_AD_SELF_TEST) == ERROR_AD_SELF_TEST) {
+		sr_err("hp_3478a: A/D has failed its internal Self Test");
+		ret = SR_ERR;
+	}
+
+	/* A/D slope error */
+	if ((error_byte & ERROR_AD_SLOPE) == ERROR_AD_SLOPE) {
+		sr_err("hp_3478a: There has been an A/D slope error");
+		ret = SR_ERR;
+	}
+
+	/* ROM Selt Test */
+	if ((error_byte & ERROR_ROM_SELF_TEST) == ERROR_ROM_SELF_TEST) {
+		sr_err("hp_3478a: The ROM Self Test has failed");
+		ret = SR_ERR;
+	}
+
+	/* RAM Selt Test */
+	if ((error_byte & ERROR_RAM_SELF_TEST) == ERROR_RAM_SELF_TEST) {
+		sr_err("hp_3478a: The RAM Self Test has failed");
+		ret = SR_ERR;
+	}
+
+	/* Selt Test */
+	if ((error_byte & ERROR_SELF_TEST) == ERROR_SELF_TEST) {
+		sr_err("hp_3478a: Self Test: Any of the CAL RAM locations have bad "
+				"checksums, or a range with a bad checksum is selected");
+		ret = SR_ERR;
+	}
+
+	return ret;
+}
+
+SR_PRIV int hp_3478a_get_status_bytes(const struct sr_dev_inst *sdi)
+{
+	int ret;
+	char *response;
+	uint8_t function_byte, status_byte, srq_byte, error_byte;
+	struct sr_scpi_dev_inst *scpi = sdi->conn;
+	struct dev_context *devc = sdi->priv;
+
+	ret = sr_scpi_get_string(scpi, "B", &response);
+	if (ret != SR_OK)
+		return ret;
+
+	if (!response)
+		return SR_ERR;
+
+	function_byte = (uint8_t)response[0];
+	status_byte = (uint8_t)response[1];
+	srq_byte = (uint8_t)response[2];
+	error_byte = (uint8_t)response[3];
+
+	g_free(response);
+
+	parse_function_byte(devc, function_byte);
+	parse_status_byte(devc, status_byte);
+	parse_srq_byte(srq_byte);
+	ret = parse_error_byte(error_byte);
+
+	return ret;
+}
+
+static void acq_send_measurement(struct sr_dev_inst *sdi)
+{
+	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;
+	struct dev_context *devc;
+	float f;
+
+	devc = sdi->priv;
+
+	packet.type = SR_DF_ANALOG;
+	packet.payload = &analog;
+
+	sr_analog_init(&analog, &encoding, &meaning, &spec, devc->enc_digits);
+
+	/* TODO: Implement NAN, depending on counts, range and value. */
+	f = devc->measurement;
+	analog.num_samples = 1;
+	analog.data = &f;
+
+	encoding.unitsize = sizeof(float);
+	encoding.is_float = TRUE;
+	encoding.digits = devc->enc_digits;
+
+	meaning.mq = devc->measurement_mq;
+	meaning.mqflags = devc->measurement_mq_flags;
+	meaning.unit = devc->measurement_unit;
+	meaning.channels = sdi->channels;
+
+	spec.spec_digits = devc->spec_digits;
+
+	sr_session_send(sdi, &packet);
+}
+
 SR_PRIV int hp_3478a_receive_data(int fd, int revents, void *cb_data)
 {
-	const struct sr_dev_inst *sdi;
+	struct sr_scpi_dev_inst *scpi;
+	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
 
 	(void)fd;
+	(void)revents;
 
-	if (!(sdi = cb_data))
+	if (!(sdi = cb_data) || !(devc = sdi->priv))
 		return TRUE;
 
-	if (!(devc = sdi->priv))
-		return TRUE;
+	scpi = sdi->conn;
 
-	if (revents == G_IO_IN) {
-		/* TODO */
-	}
+	/*
+	 * This is necessary to get the actual range for the encoding digits.
+	 * When SPoll is implemmented, this can be done via SPoll.
+	 */
+	if (hp_3478a_get_status_bytes(sdi) != SR_OK)
+		return FALSE;
+
+	/*
+	 * TODO: Implement GPIB-SPoll, to get notified by a SRQ when a new
+	 *       measurement is available. This is necessary, because when
+	 *       switching ranges, there could be a timeout.
+	 */
+	if (sr_scpi_get_double(scpi, NULL, &devc->measurement) != SR_OK)
+		return FALSE;
+
+	acq_send_measurement(sdi);
+	sr_sw_limits_update_samples_read(&devc->limits, 1);
+
+	if (sr_sw_limits_check(&devc->limits))
+		sr_dev_acquisition_stop(sdi);
 
 	return TRUE;
 }
diff --git a/src/hardware/hp-3478a/protocol.h b/src/hardware/hp-3478a/protocol.h
index a36af719..baf622bd 100644
--- a/src/hardware/hp-3478a/protocol.h
+++ b/src/hardware/hp-3478a/protocol.h
@@ -27,9 +27,137 @@
 
 #define LOG_PREFIX "hp-3478a"
 
+#define SB1_FUNCTION_BLOCK	0b11100000
+#define SB1_RANGE_BLOCK		0b00011100
+#define SB1_DIGITS_BLOCK	0b00000011
+
+/* Status Byte 1 (Function) */
+enum sb1_function {
+	FUNCTION_VDC			= 0b00100000,
+	FUNCTION_VAC			= 0b01000000,
+	FUNCTION_2WR			= 0b01100000,
+	FUNCTION_4WR			= 0b10000000,
+	FUNCTION_ADC			= 0b10100000,
+	FUNCTION_AAC			= 0b11000000,
+	FUNCTION_EXR			= 0b11100000,
+};
+
+/* Status Byte 1 (Range V DC) */
+enum sb1_range_vdc {
+	RANGE_VDC_30MV			= 0b00000100,
+	RANGE_VDC_300MV			= 0b00001000,
+	RANGE_VDC_3V			= 0b00001100,
+	RANGE_VDC_30V			= 0b00010000,
+	RANGE_VDC_300V			= 0b00010100,
+};
+
+/* Status Byte 1 (Range V AC) */
+enum sb1_range_vac {
+	RANGE_VAC_300MV			= 0b00000100,
+	RANGE_VAC_3V			= 0b00001000,
+	RANGE_VAC_30V			= 0b00001100,
+	RANGE_VAC_300V			= 0b00010000,
+};
+
+/* Status Byte 1 (Range A) */
+enum sb1_range_a {
+	RANGE_A_300MA			= 0b00000100,
+	RANGE_A_3A			= 0b00001000,
+};
+
+/* Status Byte 1 (Range Ohm) */
+enum sb1_range_ohm {
+	RANGE_OHM_30R			= 0b00000100,
+	RANGE_OHM_300R			= 0b00001000,
+	RANGE_OHM_3KR			= 0b00001100,
+	RANGE_OHM_30KR			= 0b00010000,
+	RANGE_OHM_300KR			= 0b00010100,
+	RANGE_OHM_3MR			= 0b00011000,
+	RANGE_OHM_30MR			= 0b00011100,
+};
+
+/* Status Byte 1 (Digits) */
+enum sb1_digits {
+	DIGITS_5_5			= 0b00000001,
+	DIGITS_4_5			= 0b00000010,
+	DIGITS_3_5			= 0b00000011,
+};
+
+/* Status Byte 2 */
+enum sb2_status {
+	STATUS_INT_TRIGGER		= (1 << 0),
+	STATUS_AUTO_RANGE		= (1 << 1),
+	STATUS_AUTO_ZERO		= (1 << 2),
+	STATUS_50HZ			= (1 << 3),
+	STATUS_FRONT_TERMINAL		= (1 << 4),
+	STATUS_CAL_RAM			= (1 << 5),
+	STATUS_EXT_TRIGGER		= (1 << 6),
+};
+
+/* Status Byte 3 (Serial Poll Mask) */
+enum sb3_srq {
+	SRQ_BUS_AVAIL			= (1 << 0),
+	SRQ_SYNTAX_ERR			= (1 << 2),
+	SRQ_HARDWARE_ERR		= (1 << 3),
+	SRQ_KEYBORD			= (1 << 4),
+	SRQ_CAL_FAILED			= (1 << 5),
+	SRQ_POWER_ON			= (1 << 7),
+};
+
+/* Status Byte 4 (Error) */
+enum sb4_error {
+	ERROR_SELF_TEST			= (1 << 0),
+	ERROR_RAM_SELF_TEST		= (1 << 1),
+	ERROR_ROM_SELF_TEST		= (1 << 2),
+	ERROR_AD_SLOPE			= (1 << 3),
+	ERROR_AD_SELF_TEST		= (1 << 4),
+	ERROR_AD_LINK			= (1 << 5),
+};
+
+/* Channel connector (front terminals or rear terminals. */
+enum terminal_connector {
+	TERMINAL_FRONT,
+	TERMINAL_REAR,
+};
+
+/* Possible triggers */
+enum trigger_state {
+	TRIGGER_UNDEFINED,
+	TRIGGER_EXTERNAL,
+	TRIGGER_INTERNAL,
+};
+
+/* Possible line frequencies */
+enum line_freq {
+	LINE_50HZ,
+	LINE_60HZ,
+};
+
 struct dev_context {
+	struct sr_sw_limits limits;
+
+	double measurement;
+	enum sr_mq measurement_mq;
+	enum sr_mqflag measurement_mq_flags;
+	enum sr_unit measurement_unit;
+	uint8_t enc_digits;
+	uint8_t spec_digits;
+
+	enum terminal_connector terminal;
+	enum trigger_state trigger;
+	enum line_freq line;
+	gboolean auto_zero;
+	gboolean calibration;
+};
+
+struct channel_context {
+	int index;
+	enum terminal_connector location;
 };
 
+SR_PRIV int hp_3478a_set_mq(const struct sr_dev_inst *sdi, enum sr_mq mq,
+				enum sr_mqflag mq_flags);
+SR_PRIV int hp_3478a_get_status_bytes(const struct sr_dev_inst *sdi);
 SR_PRIV int hp_3478a_receive_data(int fd, int revents, void *cb_data);
 
 #endif