[sigrok-devel] [PATCH 7/7] norma dmm: Implemented driver.

[Matthias H. <m-s...@he...>]

---
 hardware/norma-dmm/api.c      | 265 +++++++++++++++++++++++------
 hardware/norma-dmm/protocol.c | 376 +++++++++++++++++++++++++++++++++++++++++-
 hardware/norma-dmm/protocol.h |  36 +++-
 3 files changed, 618 insertions(+), 59 deletions(-)

diff --git a/hardware/norma-dmm/api.c b/hardware/norma-dmm/api.c
index fb24c7e..143f038 100644
--- a/hardware/norma-dmm/api.c
+++ b/hardware/norma-dmm/api.c
@@ -17,164 +17,321 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
 #include "protocol.h"
 
+
+static const int32_t hwopts[] = {
+	SR_CONF_CONN,
+	SR_CONF_SERIALCOMM,
+};
+
+static const int32_t hwcaps[] = {
+	SR_CONF_MULTIMETER,
+	SR_CONF_LIMIT_SAMPLES,
+	SR_CONF_LIMIT_MSEC,
+	SR_CONF_CONTINUOUS,
+};
+
+
+#define SERIALCOMM "4800/8n1/dtr=1/rts=0/flow=1"
+
+
 SR_PRIV struct sr_dev_driver norma_dmm_driver_info;
 static struct sr_dev_driver *di = &norma_dmm_driver_info;
 
+
 static int init(struct sr_context *sr_ctx)
 {
 	return std_init(sr_ctx, di, LOG_PREFIX);
 }
 
+
 static GSList *scan(GSList *options)
 {
+	struct sr_dev_inst *sdi;
 	struct drv_context *drvc;
-	GSList *devices;
-
-	(void)options;
+	struct dev_context *devc;
+	struct sr_config *src;
+	struct sr_probe *probe;
+	struct sr_serial_dev_inst *serial;
+	GSList *l, *devices;
+	int len, cnt;
+	const char *conn, *serialcomm;
+	char *buf;
+	char fmttype[10];
+	char req[10];
+	int auxtype;
+
+	#define BUF_MAX (50)
 
 	devices = NULL;
 	drvc = di->priv;
 	drvc->instances = NULL;
+	conn = serialcomm = NULL;
+
+	for (l = options; l; l = l->next) {
+		src = l->data;
+		switch (src->key) {
+		case SR_CONF_CONN:
+			conn = g_variant_get_string(src->data, NULL);
+			break;
+		case SR_CONF_SERIALCOMM:
+			serialcomm = g_variant_get_string(src->data, NULL);
+			break;
+		}
+	}
+	if (!conn)
+		return NULL;
+	if (!serialcomm)
+		serialcomm = SERIALCOMM;
+
+	if (!(serial = sr_serial_dev_inst_new(conn, serialcomm)))
+		return NULL;
+
+	if (serial_open(serial, SERIAL_RDWR | SERIAL_NONBLOCK) != SR_OK)
+		return NULL;
+
+	serial_flush(serial);
 
-	/* TODO: scan for devices, either based on a SR_CONF_CONN option
-	 * or on a USB scan. */
+	len = BUF_MAX;
+	if (!(buf = g_try_malloc(len))) {
+		sr_err("Serial buffer malloc failed.");
+		return NULL;
+	}
+
+	snprintf(req, sizeof(req), "%s\r\n",
+		 nmadmm_requests[NMADMM_REQ_IDN].reqstr);
+	for (cnt = 0; cnt < 7; cnt++) {
+		if (serial_write(serial, req, strlen(req)) == -1) {
+			sr_err("Unable to send identification request: %d %s.",
+			errno, strerror(errno));
+			return NULL;
+		}
+		len = BUF_MAX;
+		serial_readline(serial, &buf, &len, 1500);
+		if (!len)
+			continue;
+		buf[BUF_MAX-1] = '\0';
+
+		/* Match id string, e.g. "1834 065 V1.06,IF V1.02" (DM950) */
+		if (g_regex_match_simple("^1834 [^,]*,IF V*", (char*)buf,0,0)) {
+			auxtype = xgittoint(buf[7]);
+				// TODO: Will this work with non-DM950?
+			snprintf(fmttype, sizeof(fmttype), "DM9%d0", auxtype);
+			sr_spew("Norma %s DMM %s detected!", fmttype, &buf[9]);
+
+			if (!(sdi = sr_dev_inst_new(0, SR_ST_INACTIVE,
+						"Norma", fmttype, buf + 9)))
+				return NULL;
+			if (!(devc = g_try_malloc0(sizeof(*devc)))) {
+				sr_err("Device context malloc failed.");
+				return NULL;
+			}
+			devc->type = auxtype;
+			devc->version = g_strdup(&buf[9]);
+			devc->elapsed_msec = g_timer_new();
+
+			sdi->conn = serial;
+			sdi->priv = devc;
+			sdi->driver = di;
+			if (!(probe = sr_probe_new(0, SR_PROBE_ANALOG, TRUE,
+				"P1")))
+				return NULL;
+			sdi->probes = g_slist_append(sdi->probes, probe);
+			drvc->instances = g_slist_append(drvc->instances, sdi);
+			devices = g_slist_append(devices, sdi);
+			break;
+		}
+		/* The interface of the DM9x0 contains a cap that needs to
+		 charge for up to 10s before the interface works, if not powered
+		 externally. Therefore wait a little to improve chances. */
+		if (cnt == 3) {
+			sr_info("Waiting 5s to allow interface to settle.");
+			g_usleep(5 * 1000 * 1000);
+		}
+	}
+
+	g_free(buf);
+
+	serial_close(serial);
+	if (!devices)
+		sr_serial_dev_inst_free(serial);
 
 	return devices;
 }
 
+
 static GSList *dev_list(void)
 {
 	return ((struct drv_context *)(di->priv))->instances;
 }
 
+
 static int dev_clear(void)
 {
 	return std_dev_clear(di, NULL);
 }
 
+
 static int dev_open(struct sr_dev_inst *sdi)
 {
-	(void)sdi;
+	struct sr_serial_dev_inst *serial;
 
-	/* TODO: get handle from sdi->conn and open it. */
+	serial = sdi->conn;
+	if (serial_open(serial, SERIAL_RDWR | SERIAL_NONBLOCK) != SR_OK)
+		return SR_ERR;
 
 	sdi->status = SR_ST_ACTIVE;
 
 	return SR_OK;
 }
 
+
 static int dev_close(struct sr_dev_inst *sdi)
 {
-	(void)sdi;
+	struct sr_serial_dev_inst *serial;
+	struct dev_context *devc;
 
-	/* TODO: get handle from sdi->conn and close it. */
+	serial = sdi->conn;
+	if (serial && serial->fd != -1) {
+		serial_close(serial);
+		sdi->status = SR_ST_INACTIVE;
+	}
 
-	sdi->status = SR_ST_INACTIVE;
+	// Free dynamically allocated resources.
+	if ((devc = sdi->priv) && devc->version) {
+		g_free(devc->version);
+		devc->version = NULL;
+		g_timer_destroy(devc->elapsed_msec);
+	}
 
 	return SR_OK;
 }
 
+
 static int cleanup(void)
 {
-	dev_clear();
-
-	/* TODO: free other driver resources, if any. */
-
-	return SR_OK;
+	return dev_clear();
 }
 
-static int config_get(int key, GVariant **data, const struct sr_dev_inst *sdi)
-{
-	int ret;
-
-	(void)sdi;
-	(void)data;
-
-	ret = SR_OK;
-	switch (key) {
-	/* TODO */
-	default:
-		return SR_ERR_NA;
-	}
-
-	return ret;
-}
 
 static int config_set(int key, GVariant *data, const struct sr_dev_inst *sdi)
 {
-	int ret;
-
-	(void)data;
+	struct dev_context *devc;
 
 	if (sdi->status != SR_ST_ACTIVE)
 		return SR_ERR_DEV_CLOSED;
 
-	ret = SR_OK;
+	if (!(devc = sdi->priv)) {
+		sr_err("sdi->priv was NULL.");
+		return SR_ERR_BUG;
+	}
+
 	switch (key) {
-	/* TODO */
+	case SR_CONF_LIMIT_MSEC:
+		/* TODO: not yet implemented */
+		if (g_variant_get_uint64(data) == 0) {
+			sr_err("LIMIT_MSEC can't be 0.");
+			return SR_ERR;
+		}
+		devc->limit_msec = g_variant_get_uint64(data);
+		sr_dbg("Setting time limit to %" PRIu64 "ms.",
+		       devc->limit_msec);
+		break;
+	case SR_CONF_LIMIT_SAMPLES:
+		devc->limit_samples = g_variant_get_uint64(data);
+		sr_dbg("Setting sample limit to %" PRIu64 ".",
+		       devc->limit_samples);
+		break;
 	default:
-		ret = SR_ERR_NA;
+		return SR_ERR_NA;
 	}
 
-	return ret;
+	return SR_OK;
 }
 
+
 static int config_list(int key, GVariant **data, const struct sr_dev_inst *sdi)
 {
-	int ret;
-
 	(void)sdi;
-	(void)data;
 
-	ret = SR_OK;
 	switch (key) {
-	/* TODO */
+	case SR_CONF_SCAN_OPTIONS:
+		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
+				hwopts, ARRAY_SIZE(hwopts), sizeof(int32_t));
+		break;
+	case SR_CONF_DEVICE_OPTIONS:
+		*data = g_variant_new_fixed_array(G_VARIANT_TYPE_INT32,
+				hwcaps, ARRAY_SIZE(hwcaps), sizeof(int32_t));
+		break;
 	default:
 		return SR_ERR_NA;
 	}
 
-	return ret;
+	return SR_OK;
 }
 
+
 static int dev_acquisition_start(const struct sr_dev_inst *sdi,
 				    void *cb_data)
 {
+	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
+
 	(void)sdi;
 	(void)cb_data;
 
+	if (!sdi || !cb_data || !(devc = sdi->priv))
+		return SR_ERR_BUG;
+
 	if (sdi->status != SR_ST_ACTIVE)
 		return SR_ERR_DEV_CLOSED;
 
-	/* TODO: configure hardware, reset acquisition state, set up
-	 * callbacks and send header packet. */
+	devc->cb_data = cb_data;
+
+	/* Send header packet to the session bus. */
+	std_session_send_df_header(cb_data, LOG_PREFIX);
+
+	/* Start timer, if required. */
+	if (devc->limit_msec)
+		g_timer_start(devc->elapsed_msec);
+
+	/* Poll every 100ms, or whenever some data comes in. */
+	serial = sdi->conn;
+	sr_source_add(serial->fd, G_IO_IN, 100, norma_dmm_receive_data,
+		      (void *)sdi);
 
 	return SR_OK;
 }
 
+
 static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data)
 {
-	(void)cb_data;
-
-	if (sdi->status != SR_ST_ACTIVE)
-		return SR_ERR_DEV_CLOSED;
+	struct dev_context *devc;
 
-	/* TODO: stop acquisition. */
+	/* Stop timer, if required. */
+	if (sdi && (devc = sdi->priv) && devc->limit_msec)
+		g_timer_stop(devc->elapsed_msec);
 
-	return SR_OK;
+	return std_dev_acquisition_stop_serial(sdi, cb_data, dev_close,
+			sdi->conn, LOG_PREFIX);
 }
 
+
 SR_PRIV struct sr_dev_driver norma_dmm_driver_info = {
 	.name = "norma-dmm",
-	.longname = "norma-dmm",
+	.longname = "Norma DM910..950, Siemens B1024..1028 DMMs",
 	.api_version = 1,
 	.init = init,
 	.cleanup = cleanup,
 	.scan = scan,
 	.dev_list = dev_list,
 	.dev_clear = dev_clear,
-	.config_get = config_get,
+	.config_get = NULL,
 	.config_set = config_set,
 	.config_list = config_list,
 	.dev_open = dev_open,
diff --git a/hardware/norma-dmm/protocol.c b/hardware/norma-dmm/protocol.c
index 2dd0b1b..3b2bff7 100644
--- a/hardware/norma-dmm/protocol.c
+++ b/hardware/norma-dmm/protocol.c
@@ -19,10 +19,308 @@
 
 #include "protocol.h"
 
+#include <ctype.h>
+#include <errno.h>
+#include <math.h>
+#include <string.h>
+
+
+static int nma_send_req(const struct sr_dev_inst *sdi, enum nmadmm_req_t reqt,
+		char* params);
+
+
+/** Convert hexadecimal digit to int.
+ *  \param[in] xgit Hexadecimal digit to convert.
+ *  \return Int value of xgit (0 on invalid xgit).
+ */
+SR_PRIV int xgittoint(char xgit)
+{
+	if ((xgit >= '0') && (xgit <= '9'))
+		return xgit - '0';
+	xgit = tolower(xgit);
+	if ((xgit >= 'a') && (xgit <= 'f'))
+		return xgit - 'a';
+	return 0;
+}
+
+
+/** Process received line. It consists of 20 hex digits + \r\n,
+ *  e.g. '08100400018100400000'. */
+static void nma_process_line(const struct sr_dev_inst *sdi)
+{
+	struct dev_context *devc;
+	int pos, flags;
+	int vt, range;	/* Measurement value type, range in device format */
+	int mmode, devstat;	/* Measuring mode, device status */
+	float value;	/* Measured value */
+	float scale;	/* Scaling factor depending on range and function */
+
+	struct sr_datafeed_analog analog;
+	struct sr_datafeed_packet packet;
+
+	devc = sdi->priv;
+
+	devc->buf[20] = '\0';
+
+	sr_spew("Received line '%s'.", devc->buf);
+
+	/* Check line */
+	if (strlen((char*)devc->buf) != 20) {
+		sr_err("line: Invalid status '%s', must be 20 hex digits");
+		devc->buflen = 0;
+		return;
+	}
+	for (pos = 0; pos < 20; pos++)
+		if (!isxdigit(devc->buf[pos])) {
+			sr_err("line: Expected hex digit in '%s' at pos %d!",
+				devc->buf, pos);
+			devc->buflen = 0;
+			return;
+		}
+
+	/* Start decoding. */
+	value = 0.0;
+	scale = 1.0;
+	memset(&analog, 0, sizeof(analog));
+
+	/* The numbers are hex digits, starting from 0. */
+	/* 0: Keyboard status, currently not interesting. */
+	/* 1: Central switch status, currently not interesting. */
+	/* 2: Type of measured value */
+	vt = xgittoint(devc->buf[2]);
+	switch (vt) {
+	case 0:	analog.mq = SR_MQ_VOLTAGE;
+		break;
+	case 1: analog.mq = SR_MQ_CURRENT;	// 2A
+		break;
+	case 2:	analog.mq = SR_MQ_RESISTANCE;
+		break;
+	case 3:	analog.mq = SR_MQ_CAPACITANCE;
+		break;
+	case 4: analog.mq = SR_MQ_TEMPERATURE;
+		break;
+	case 5:	analog.mq = SR_MQ_FREQUENCY;
+		break;
+	case 6:	analog.mq = SR_MQ_CURRENT;	// 10A
+		break;
+	case 7:	analog.mq = SR_MQ_GAIN;		// TODO: Scale factor
+		break;
+	case 8:	analog.mq = SR_MQ_GAIN;		// Percentage
+		scale /= 100.0;
+		break;
+	case 9:	analog.mq = SR_MQ_GAIN;		// dB
+		scale /= 100.0;
+		break;
+	default:sr_err("Unknown value type 0x%02x", vt);
+	    break;
+	}
+	/* 3: Measurement range for measured value */
+	range = xgittoint(devc->buf[3]);
+	switch (vt) {
+	case 0: // V
+		scale *= pow(10.0, range - 5);
+		break;
+	case 1: // A
+		scale *= pow(10.0, range - 7);
+		break;
+	case 2: // Ω
+		scale *= pow(10.0, range - 2);
+		break;
+	case 3: // F
+		scale *= pow(10.0, range - 12);
+		break;
+	case 4: // °C
+		scale *= pow(10.0, range - 1);
+		break;
+	case 5: // Hz
+		scale *= pow(10.0, range - 2);
+		break;
+	// No default, other value types have fixed display format
+	}
+
+	/* 5: Sign and 1st digit */
+	flags = xgittoint(devc->buf[5]);
+	value = (flags & 0x03);
+	if (flags & 0x04) scale *= -1;
+	/* 6-9: 2nd-4th digit */
+	for (pos = 6; pos < 10; pos++)
+		value = value * 10 + xgittoint(devc->buf[pos]);
+	value *= scale;
+
+	/* 10: Display counter */
+	mmode = xgittoint(devc->buf[10]);
+	switch (mmode) {
+	case 0:	/* Frequency */
+		analog.unit = SR_UNIT_HERTZ;
+		break;
+	case 1:	/* V TRMS, only type 5  */
+		analog.unit = SR_UNIT_VOLT;
+		analog.mqflags |= (SR_MQFLAG_AC | SR_MQFLAG_DC | SR_MQFLAG_RMS);
+		break;
+	case 2:	/* V AC */
+		analog.unit = SR_UNIT_VOLT;
+		analog.mqflags |= SR_MQFLAG_AC;
+		if (devc->type >= 3) analog.mqflags |= SR_MQFLAG_RMS;
+		break;
+	case 3:	/* V DC */
+		analog.unit = SR_UNIT_VOLT;
+		analog.mqflags |= SR_MQFLAG_DC;
+		break;
+	case 4:	/* Ohm */
+		analog.unit = SR_UNIT_OHM;
+		break;
+	case 5:	/* Continuity */
+		analog.unit = SR_UNIT_BOOLEAN;
+		analog.mq = SR_MQ_CONTINUITY;
+		/* TODO Continuity handling is a bit odd in sigrok. */
+		break;
+	case 6: /* Degree Celsius */
+		analog.unit = SR_UNIT_CELSIUS;
+		break;
+	case 7:	/* Capacity */
+		analog.unit = SR_UNIT_FARAD;
+		break;
+	case 8: /* Current DC */
+		analog.unit = SR_UNIT_AMPERE;
+		analog.mqflags |= SR_MQFLAG_DC;
+		break;
+	case 9:	/* Current AC */
+		analog.unit = SR_UNIT_AMPERE;
+		analog.mqflags |= SR_MQFLAG_AC;
+		if (devc->type >= 3) analog.mqflags |= SR_MQFLAG_RMS;
+		break;
+	case 0xA:/* Current TRMS, only type 5	 */
+		analog.unit = SR_UNIT_AMPERE;
+		analog.mqflags |= (SR_MQFLAG_AC | SR_MQFLAG_DC | SR_MQFLAG_RMS);
+		break;
+	case 0x0B:/* Diode */
+		analog.unit = SR_UNIT_VOLT;
+		analog.mqflags |= (SR_MQFLAG_DIODE | SR_MQFLAG_DC);
+		break;
+	default:
+		sr_err("unknown mmode 0x%02x", mmode);
+		break;
+	}
+
+	/* 11: Device status */
+	devstat = xgittoint(devc->buf[11]);
+
+	switch (devstat) {
+	case 1:	// Normal measurement
+		break;
+	case 2:	// Input loop (limit, reference values)
+		break;
+	case 3: // TRANS/SENS
+		break;
+	case 4:	// Error
+		sr_err("Device error. Fuse?"); // TODO: Wirklich abbrechen???
+		devc->buflen = 0;
+		return;	// Cannot continue.
+	default:
+		sr_err("Unknown device status 0x02x", devstat);
+		break;
+	}
+
+	/* 12-19: Flags and display symbols */
+	/* 12, 13 */
+	flags = (xgittoint(devc->buf[12]) << 8) | xgittoint(devc->buf[13]);
+	/* 0x80: PRINT TODO: Stop polling when discovered? */
+	/* 0x40: EXTR  */
+	if (analog.mq == SR_MQ_CONTINUITY) {
+		if (flags & 0x20) value = 1.0; /* Beep */
+		else value = 0.0;
+	}
+	/* 0x10: AVG */
+	/* 0x08: Diode */
+	if (flags & 0x04) /* REL */
+		analog.mqflags |= SR_MQFLAG_RELATIVE;
+	/* 0x02: SHIFT	*/
+	if (flags & 0x01) /* % */
+		analog.unit = SR_UNIT_PERCENTAGE;
+
+	/* 14, 15 */
+	flags = (xgittoint(devc->buf[14]) << 8) | xgittoint(devc->buf[15]);
+	if (!(flags & 0x80))	/* MAN Manual range */
+		analog.mqflags |= SR_MQFLAG_AUTORANGE;
+	if (flags & 0x40)/* LOBAT1 Low battery,measurement still within specs.*/
+		devc->lowbatt = 1;
+	/* 0x20: PEAK	*/
+	/* 0x10: COUNT	*/
+	if (flags & 0x08)	// HOLD
+		analog.mqflags |= SR_MQFLAG_HOLD;
+	/* 0x04: LIMIT	*/
+	if (flags & 0x02) 	// MAX
+		analog.mqflags |= SR_MQFLAG_MAX;
+	if (flags & 0x01) 	// MIN
+		analog.mqflags |= SR_MQFLAG_MIN;
+
+	/* 16, 17 */
+	flags = (xgittoint(devc->buf[16]) << 8) | xgittoint(devc->buf[17]);
+	/* 0xe0: undefined */
+	if (flags & 0x10) { /* LOBATT2  Low battery, measurement inaccurate */
+		devc->lowbatt = 2;
+		sr_warn("Low battery, measurement quality degraded!");
+	}
+	/* 0x08: SCALED */
+	/* 0x04: RATE (=lower resolution, allows higher rata rate up to 10/s. */
+	/* 0x02: Current Clamp */
+	if (flags & 0x01) { /* dB	*/
+		if (analog.unit == SR_UNIT_VOLT)
+			analog.unit = SR_UNIT_DECIBEL_VOLT;
+		/* TODO: The Norma has an adjustable dB reference value. If
+		 * changed from default, this is not correct. */
+		else
+			analog.unit = SR_UNIT_UNITLESS;
+	}
+
+	/* 18, 19 */
+	/* flags = (xgittoint(devc->buf[18]) << 8) | xgittoint(devc->buf[19]);*/
+	/* 0x80: Undefined. */
+	/* 0x40: Remote mode, keyboard locked */
+	/* 0x38: Undefined. */
+	/* 0x04: MIN>MAX */
+	/* 0x02: Measured value < Min */
+	/* 0x01: Measured value > Max */
+
+	/* 4: Flags. Evaluating this after setting value!  */
+	flags = xgittoint(devc->buf[4]);
+	if (flags & 0x04) { // Invalid value
+	    value = NAN;
+	}
+	else if (flags & 0x01) { // Overload
+	    value =  INFINITY;
+	}
+	if (flags & 0x02) { // Duplicate value, has been sent before.
+	    sr_spew("Duplicate value, dismissing!");
+	    devc->buflen = 0;
+	    return;
+	}
+
+	sr_spew("range=%d/scale=%f/value=%f",range,(double)scale,(double)value);
+
+	/* Finish and send packet */
+	analog.probes = sdi->probes;
+	analog.num_samples = 1;
+	analog.data = &value;
+
+	memset(&packet, 0, sizeof(packet));
+	packet.type = SR_DF_ANALOG;
+	packet.payload = &analog;
+	sr_session_send(devc->cb_data, &packet);
+
+	/* Finish processing */
+	devc->num_samples++;
+	devc->buflen = 0;
+}
+
+
 SR_PRIV int norma_dmm_receive_data(int fd, int revents, void *cb_data)
 {
-	const struct sr_dev_inst *sdi;
+	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
+	struct sr_serial_dev_inst *serial;
+	int len;
+	gboolean terminating;
 
 	(void)fd;
 
@@ -32,9 +330,83 @@ SR_PRIV int norma_dmm_receive_data(int fd, int revents, void *cb_data)
 	if (!(devc = sdi->priv))
 		return TRUE;
 
+	serial = sdi->conn;
 	if (revents == G_IO_IN) {
-		/* TODO */
+		/* Serial data arrived. */
+		while(NMADMM_BUFSIZE - devc->buflen - 1 > 0) {
+			len = serial_read(serial, devc->buf + devc->buflen, 1);
+			if (len < 1)
+				break;
+			devc->buflen += len;
+			*(devc->buf + devc->buflen) = '\0';
+			if (*(devc->buf + devc->buflen - 1) == '\n') {
+				/* TODO: According to specs, should be \r, but
+				 * then we'd have to get rid of the \n */
+				devc->last_req_pending = FALSE;
+				nma_process_line(sdi);
+				break;
+			}
+		}
+	}
+
+	// If number of samples or time limit reached, stop aquisition.
+	terminating = FALSE;
+	if (devc->limit_samples && (devc->num_samples >= devc->limit_samples)) {
+		sdi->driver->dev_acquisition_stop(sdi, cb_data);
+		terminating = TRUE;
+	}
+
+	if (devc->limit_msec) {
+		gdouble elapsed_s = g_timer_elapsed(devc->elapsed_msec, NULL);
+		if ((elapsed_s  * 1000) >= devc->limit_msec) {
+			sdi->driver->dev_acquisition_stop(sdi, cb_data);
+			terminating = TRUE;
+		}
+	}
+
+	// Request next package
+	if (!terminating && !devc->last_req_pending) {
+		if (nma_send_req(sdi, NMADMM_REQ_STATUS, NULL) != SR_OK)
+			return FALSE;
 	}
 
 	return TRUE;
 }
+
+
+static int nma_send_req(const struct sr_dev_inst *sdi, enum nmadmm_req_t req,
+		char* params)
+{
+	struct sr_serial_dev_inst *serial;
+	struct dev_context *devc;
+	char buf[NMADMM_BUFSIZE];
+	int len;
+
+
+	if (!sdi || !(serial = sdi->conn) || !(devc = sdi->priv))
+		return SR_ERR_BUG;
+
+	len = snprintf(buf, sizeof(buf), "%s%s\r\n",
+		nmadmm_requests[req].reqstr, params?params:"");
+
+	sr_spew("Sending request: '%s'", buf);
+
+	devc->last_req = req;
+	devc->last_req_pending = TRUE;
+
+	if (serial_write(serial, buf, len) == -1) {
+		sr_err("Unable to send request: %d %s.",
+			errno, strerror(errno));
+		devc->last_req_pending = FALSE;
+		return SR_ERR;
+	}
+
+	return SR_OK;
+}
+
+
+SR_PRIV const struct nmadmm_req nmadmm_requests[] = {
+	{ NMADMM_REQ_IDN, "IDN?"},
+	{ NMADMM_REQ_IDN, "STATUS?"},
+	{ 0, NULL }
+};
diff --git a/hardware/norma-dmm/protocol.h b/hardware/norma-dmm/protocol.h
index a8af261..70a777a 100644
--- a/hardware/norma-dmm/protocol.h
+++ b/hardware/norma-dmm/protocol.h
@@ -34,18 +34,48 @@
 #define sr_warn(s, args...) sr_warn(LOG_PREFIX s, ## args)
 #define sr_err(s, args...) sr_err(LOG_PREFIX s, ## args)
 
+#define NMADMM_BUFSIZE  256
+
+/** Norma DMM request types (used ones only, the multimeters support about 50).
+ */
+enum nmadmm_req_t {
+	NMADMM_REQ_IDN = 0,	/**< Request identity */
+	NMADMM_REQ_STATUS,	/**< Request device status (value + ...) */
+};
+
+/** Defines requests used to communicate with device. */
+struct nmadmm_req {
+	enum nmadmm_req_t req_t;	/** Request type. */
+	const char* reqstr;		/** Request string */
+};
+
+/** Strings for requests. */
+extern const struct nmadmm_req nmadmm_requests[];
+
 /** Private, per-device-instance driver context. */
 struct dev_context {
 	/* Model-specific information */
-
+	char*	version;	/**< Version string */
+	int	type;		/**< DM9x0, e.g. 5 = DM950 */
 	/* Acquisition settings */
+	uint64_t limit_samples;	/**< Target number of samples */
+	uint64_t limit_msec;	/**< Target sampling time */
 
-	/* Operational state */
+	/* Opaque pointer passed in by frontend. */
+	void *cb_data;
 
+	/* Operational state */
+	enum nmadmm_req_t last_req;	/**< Last request. */
+	gboolean last_req_pending;	/**< Last request not answered yet.*/
+	int	lowbatt;		/**< Low battery. 1=low, 2=critical.*/
 	/* Temporary state across callbacks */
-
+	uint64_t num_samples;		/**< Current #samples. */
+	GTimer* elapsed_msec;		/**< Used for sampling with limit_msec*/
+	unsigned char buf[NMADMM_BUFSIZE];	/**< Buffer for read callback */
+	int buflen;			/**< Data len in buf */
 };
 
 SR_PRIV int norma_dmm_receive_data(int fd, int revents, void *cb_data);
+SR_PRIV int xgittoint(char xgit);
 
 #endif
-- 
1.8.0