diff --git a/hardware/serial-dmm/api.c b/hardware/serial-dmm/api.c
index 4ac923ca..32027770 100644
--- a/hardware/serial-dmm/api.c
+++ b/hardware/serial-dmm/api.c
@@ -49,30 +49,34 @@ static const char *probe_names[] = {
 
 SR_PRIV struct sr_dev_driver digitek_dt4000zc_driver_info;
 SR_PRIV struct sr_dev_driver tekpower_tp4000zc_driver_info;
+SR_PRIV struct sr_dev_driver metex_me31_driver_info;
 
-static struct sr_dev_driver *di_digitek_dt4000zc = &digitek_dt4000zc_driver_info;
-static struct sr_dev_driver *di_tekpower_tp4000zc = &tekpower_tp4000zc_driver_info;
+static struct sr_dev_driver *di_dt4000zc = &digitek_dt4000zc_driver_info;
+static struct sr_dev_driver *di_tp4000zc = &tekpower_tp4000zc_driver_info;
+static struct sr_dev_driver *di_me31 = &metex_me31_driver_info;
 
 /* After hw_init() this will point to a device-specific entry (see above). */
 static struct sr_dev_driver *di = NULL;
 
 SR_PRIV struct dmm_info dmms[] = {
 	{
-		"Digitek", "DT4000ZC",
-		"2400/8n1", 2400,
-		FS9721_PACKET_SIZE,
-		sr_fs9721_packet_valid,
-		sr_fs9721_parse,
+		"Digitek", "DT4000ZC", "2400/8n1", 2400,
+		FS9721_PACKET_SIZE, NULL,
+		sr_fs9721_packet_valid, sr_fs9721_parse,
 		dmm_details_dt4000zc,
 	},
 	{
-		"TekPower", "TP4000ZC",
-		"2400/8n1", 2400,
-		FS9721_PACKET_SIZE,
-		sr_fs9721_packet_valid,
-		sr_fs9721_parse,
+		"TekPower", "TP4000ZC", "2400/8n1", 2400,
+		FS9721_PACKET_SIZE, NULL,
+		sr_fs9721_packet_valid, sr_fs9721_parse,
 		dmm_details_tp4000zc,
 	},
+	{
+		"Metex", "ME-31", "600/7n2/rts=0/dtr=1", 600,
+		METEX14_PACKET_SIZE, sr_metex14_packet_request,
+		sr_metex14_packet_valid, sr_metex14_parse,
+		NULL,
+	},
 };
 
 /* Properly close and free all devices. */
@@ -111,9 +115,11 @@ static int hw_init(int dmm)
 	}
 
 	if (dmm == DIGITEK_DT4000ZC)
-		di = di_digitek_dt4000zc;
+		di = di_dt4000zc;
 	if (dmm == TEKPOWER_TP4000ZC)
-		di = di_tekpower_tp4000zc;
+		di = di_tp4000zc;
+	if (dmm == METEX_ME31)
+		di = di_me31;
 	sr_dbg("Selected '%s' subdriver.", di->name);
 
 	di->priv = drvc;
@@ -131,6 +137,11 @@ static int hw_init_tekpower_tp4000zc(void)
 	return hw_init(TEKPOWER_TP4000ZC);
 }
 
+static int hw_init_metex_me31(void)
+{
+	return hw_init(METEX_ME31);
+}
+
 static GSList *scan(const char *conn, const char *serialcomm, int dmm)
 {
 	struct sr_dev_inst *sdi;
@@ -146,10 +157,10 @@ static GSList *scan(const char *conn, const char *serialcomm, int dmm)
 	if (!(serial = sr_serial_dev_inst_new(conn, serialcomm)))
 		return NULL;
 
-	if (serial_open(serial, SERIAL_RDONLY | SERIAL_NONBLOCK) != SR_OK)
+	if (serial_open(serial, SERIAL_RDWR | SERIAL_NONBLOCK) != SR_OK)
 		return NULL;
 
-	sr_info("Probing port %s readonly.", conn);
+	sr_info("Probing port %s.", conn);
 
 	drvc = di->priv;
 	devices = NULL;
@@ -164,6 +175,14 @@ static GSList *scan(const char *conn, const char *serialcomm, int dmm)
 	/* Let's get a bit of data and see if we can find a packet. */
 	len = sizeof(buf);
 
+	/* Request a packet if the DMM requires this. */
+	if (dmms[dmm].packet_request) {
+		if ((ret = dmms[dmm].packet_request(serial)) < 0) {
+			sr_err("Failed to request packet: %d.", ret);
+			return FALSE;
+		}
+	}
+
 	ret = serial_stream_detect(serial, buf, &len, dmms[dmm].packet_size,
 				   dmms[dmm].packet_valid, 1000,
 				   dmms[dmm].baudrate);
@@ -234,6 +253,8 @@ static GSList *hw_scan(GSList *options)
 		dmm = 0;
 	if (!strcmp(di->name, "tekpower-tp4000zc"))
 		dmm = 1;
+	if (!strcmp(di->name, "metex-me31"))
+		dmm = 2;
 
 	if (serialcomm) {
 		/* Use the provided comm specs. */
@@ -264,7 +285,7 @@ static int hw_dev_open(struct sr_dev_inst *sdi)
 		return SR_ERR_BUG;
 	}
 
-	if (serial_open(devc->serial, SERIAL_RDONLY) != SR_OK)
+	if (serial_open(devc->serial, SERIAL_RDWR | SERIAL_NONBLOCK) != SR_OK)
 		return SR_ERR;
 
 	sdi->status = SR_ST_ACTIVE;
@@ -393,6 +414,8 @@ static int hw_dev_acquisition_start(const struct sr_dev_inst *sdi,
 		receive_data = digitek_dt4000zc_receive_data;
 	if (!strcmp(di->name, "tekpower-tp4000zc"))
 		receive_data = tekpower_tp4000zc_receive_data;
+	if (!strcmp(di->name, "metex-me31"))
+		receive_data = metex_me31_receive_data;
 
 	/* Poll every 50ms, or whenever some data comes in. */
 	sr_source_add(devc->serial->fd, G_IO_IN, 50,
@@ -462,3 +485,21 @@ SR_PRIV struct sr_dev_driver tekpower_tp4000zc_driver_info = {
 	.dev_acquisition_stop = hw_dev_acquisition_stop,
 	.priv = NULL,
 };
+
+SR_PRIV struct sr_dev_driver metex_me31_driver_info = {
+	.name = "metex-me31",
+	.longname = "Metex ME-31",
+	.api_version = 1,
+	.init = hw_init_metex_me31,
+	.cleanup = hw_cleanup,
+	.scan = hw_scan,
+	.dev_list = hw_dev_list,
+	.dev_clear = clear_instances,
+	.dev_open = hw_dev_open,
+	.dev_close = hw_dev_close,
+	.info_get = hw_info_get,
+	.dev_config_set = hw_dev_config_set,
+	.dev_acquisition_start = hw_dev_acquisition_start,
+	.dev_acquisition_stop = hw_dev_acquisition_stop,
+	.priv = NULL,
+};
diff --git a/hardware/serial-dmm/core b/hardware/serial-dmm/core
new file mode 100644
index 00000000..7dfc1685
Binary files /dev/null and b/hardware/serial-dmm/core differ
diff --git a/hardware/serial-dmm/protocol.c b/hardware/serial-dmm/protocol.c
index a3f25d0e..479e954e 100644
--- a/hardware/serial-dmm/protocol.c
+++ b/hardware/serial-dmm/protocol.c
@@ -74,7 +74,8 @@ static void handle_packet(const uint8_t *buf, struct dev_context *devc,
 	dmms[dmm].packet_parse(buf, &floatval, analog, info);
 	analog->data = &floatval;
 
-	dmms[dmm].dmm_details(analog, info);
+	if (dmms[dmm].dmm_details)
+		dmms[dmm].dmm_details(analog, info);
 
 	if (analog->mq != -1) {
 		/* Got a measurement. */
@@ -120,6 +121,7 @@ static int receive_data(int fd, int revents, int dmm, void *info, void *cb_data)
 {
 	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
+	int ret;
 
 	(void)fd;
 
@@ -132,6 +134,15 @@ static int receive_data(int fd, int revents, int dmm, void *info, void *cb_data)
 	if (revents == G_IO_IN) {
 		/* Serial data arrived. */
 		handle_new_data(devc, dmm, info);
+	} else {
+		/* Timeout, send another packet request (if DMM needs it). */
+		if (dmms[dmm].packet_request) {
+			ret = dmms[dmm].packet_request(devc->serial);
+			if (ret < 0) {
+				sr_err("Failed to request packet: %d.", ret);
+				return FALSE;
+			}
+		}
 	}
 
 	if (devc->num_samples >= devc->limit_samples) {
@@ -156,3 +167,10 @@ SR_PRIV int tekpower_tp4000zc_receive_data(int fd, int revents, void *cb_data)
 
 	return receive_data(fd, revents, TEKPOWER_TP4000ZC, &info, cb_data);
 }
+
+SR_PRIV int metex_me31_receive_data(int fd, int revents, void *cb_data)
+{
+	struct metex14_info info;
+
+	return receive_data(fd, revents, METEX_ME31, &info, cb_data);
+}
diff --git a/hardware/serial-dmm/protocol.h b/hardware/serial-dmm/protocol.h
index a4333fde..7b676a39 100644
--- a/hardware/serial-dmm/protocol.h
+++ b/hardware/serial-dmm/protocol.h
@@ -32,6 +32,7 @@
 enum {
 	DIGITEK_DT4000ZC,
 	TEKPOWER_TP4000ZC,
+	METEX_ME31,
 };
 
 struct dmm_info {
@@ -40,13 +41,14 @@ struct dmm_info {
 	char *conn;
 	uint32_t baudrate;
 	int packet_size;
+	int (*packet_request)(struct sr_serial_dev_inst *);
 	gboolean (*packet_valid)(const uint8_t *);
 	int (*packet_parse)(const uint8_t *, float *,
 			    struct sr_datafeed_analog *, void *);
 	void (*dmm_details)(struct sr_datafeed_analog *, void *);
 };
 
-SR_PRIV struct dmm_info dmms[2];
+SR_PRIV struct dmm_info dmms[3];
 
 #define DMM_BUFSIZE 256
 
@@ -70,6 +72,7 @@ struct dev_context {
 
 SR_PRIV int digitek_dt4000zc_receive_data(int fd, int revents, void *cb_data);
 SR_PRIV int tekpower_tp4000zc_receive_data(int fd, int revents, void *cb_data);
+SR_PRIV int metex_me31_receive_data(int fd, int revents, void *cb_data);
 
 SR_PRIV void dmm_details_tp4000zc(struct sr_datafeed_analog *analog, void *info);
 SR_PRIV void dmm_details_dt4000zc(struct sr_datafeed_analog *analog, void *info);
diff --git a/hwdriver.c b/hwdriver.c
index 95bdbbf5..df24f15e 100644
--- a/hwdriver.c
+++ b/hwdriver.c
@@ -116,6 +116,7 @@ extern SR_PRIV struct sr_dev_driver radioshackdmm_driver_info;
 #ifdef HAVE_HW_SERIAL_DMM
 extern SR_PRIV struct sr_dev_driver digitek_dt4000zc_driver_info;
 extern SR_PRIV struct sr_dev_driver tekpower_tp4000zc_driver_info;
+extern SR_PRIV struct sr_dev_driver metex_me31_driver_info;
 #endif
 #ifdef HAVE_HW_UNI_T_DMM
 extern SR_PRIV struct sr_dev_driver uni_t_ut61d_driver_info;
@@ -172,6 +173,7 @@ static struct sr_dev_driver *drivers_list[] = {
 #ifdef HAVE_HW_SERIAL_DMM
 	&digitek_dt4000zc_driver_info,
 	&tekpower_tp4000zc_driver_info,
+	&metex_me31_driver_info,
 #endif
 #ifdef HAVE_HW_UNI_T_DMM
 	&uni_t_ut61d_driver_info,
diff --git a/libsigrok-internal.h b/libsigrok-internal.h
index 8fc73dc7..bed792b0 100644
--- a/libsigrok-internal.h
+++ b/libsigrok-internal.h
@@ -200,6 +200,7 @@ struct metex14_info {
 	gboolean is_kilo, is_mega;
 };
 
+SR_PRIV int sr_metex14_packet_request(struct sr_serial_dev_inst *serial);
 SR_PRIV gboolean sr_metex14_packet_valid(const uint8_t *buf);
 SR_PRIV int sr_metex14_parse(const uint8_t *buf, float *floatval,
 			     struct sr_datafeed_analog *analog, void *info);