diff --git a/device.c b/device.c
index cf2fd878..0167a220 100644
--- a/device.c
+++ b/device.c
@@ -350,9 +350,34 @@ SR_PRIV void sr_serial_dev_inst_free(struct sr_serial_dev_inst *serial)
 	g_free(serial->serialcomm);
 	g_free(serial);
 }
-
 #endif
 
+SR_PRIV struct sr_usbtmc_dev_inst *sr_usbtmc_dev_inst_new(const char *device)
+{
+	struct sr_usbtmc_dev_inst *usbtmc;
+
+	if (!device) {
+		sr_err("Device name required.");
+		return NULL;
+	}
+
+	if (!(usbtmc = g_try_malloc0(sizeof(struct sr_usbtmc_dev_inst)))) {
+		sr_err("USBTMC device instance malloc failed.");
+		return NULL;
+	}
+
+	usbtmc->device = g_strdup(device);
+	usbtmc->fd = -1;
+
+	return usbtmc;
+}
+
+SR_PRIV void sr_usbtmc_dev_inst_free(struct sr_usbtmc_dev_inst *usbtmc)
+{
+	g_free(usbtmc->device);
+	g_free(usbtmc);
+}
+
 /**
  * Get the list of devices/instances of the specified driver.
  *
diff --git a/hardware/rigol-ds/api.c b/hardware/rigol-ds/api.c
index 0f997ebb..31342c23 100644
--- a/hardware/rigol-ds/api.c
+++ b/hardware/rigol-ds/api.c
@@ -217,7 +217,7 @@ static int probe_port(const char *port, GSList **devices)
 {
 	struct dev_context *devc;
 	struct sr_dev_inst *sdi;
-	struct sr_serial_dev_inst *serial;
+	struct sr_usbtmc_dev_inst *usbtmc;
 	struct sr_probe *probe;
 	unsigned int i;
 	int len, num_tokens;
@@ -227,17 +227,17 @@ static int probe_port(const char *port, GSList **devices)
 	gchar **tokens, *channel_name;
 
 	*devices = NULL;
-	if (!(serial = sr_serial_dev_inst_new(port, NULL)))
+	if (!(usbtmc = sr_usbtmc_dev_inst_new(port)))
 		return SR_ERR_MALLOC;
 
-	if (serial_open(serial, SERIAL_RDWR) != SR_OK)
+	if ((usbtmc->fd = open(usbtmc->device, O_RDWR)) < 0)
 		return SR_ERR;
-	len = serial_write(serial, "*IDN?", 5);
-	len = serial_read(serial, buf, sizeof(buf));
-	if (serial_close(serial) != SR_OK)
+	len = write(usbtmc->fd, "*IDN?", 5);
+	len = read(usbtmc->fd, buf, sizeof(buf));
+	if (close(usbtmc->fd) < 0)
 		return SR_ERR;
 
-	sr_serial_dev_inst_free(serial);
+	sr_usbtmc_dev_inst_free(usbtmc);
 
 	if (len == 0)
 		return SR_ERR_NA;
@@ -277,10 +277,10 @@ static int probe_port(const char *port, GSList **devices)
 
 	g_strfreev(tokens);
 
-	if (!(sdi->conn = sr_serial_dev_inst_new(port, NULL)))
+	if (!(sdi->conn = sr_usbtmc_dev_inst_new(port)))
 		return SR_ERR_MALLOC;
 	sdi->driver = di;
-	sdi->inst_type = SR_INST_SERIAL;
+	sdi->inst_type = SR_INST_USBTMC;
 
 	if (!(devc = g_try_malloc0(sizeof(struct dev_context))))
 		return SR_ERR_MALLOC;
@@ -399,8 +399,9 @@ static GSList *dev_list(void)
 
 static int dev_open(struct sr_dev_inst *sdi)
 {
+	struct sr_usbtmc_dev_inst *usbtmc = sdi->conn;
 
-	if (serial_open(sdi->conn, SERIAL_RDWR) != SR_OK)
+	if ((usbtmc->fd = open(usbtmc->device, O_RDWR)) < 0)
 		return SR_ERR;
 
 	if (rigol_ds_get_dev_cfg(sdi) != SR_OK)
@@ -413,11 +414,12 @@ static int dev_open(struct sr_dev_inst *sdi)
 
 static int dev_close(struct sr_dev_inst *sdi)
 {
-	struct sr_serial_dev_inst *serial;
+	struct sr_usbtmc_dev_inst *usbtmc;
 
-	serial = sdi->conn;
-	if (serial && serial->fd != -1) {
-		serial_close(serial);
+	usbtmc = sdi->conn;
+	if (usbtmc && usbtmc->fd != -1) {
+		close(usbtmc->fd);
+		usbtmc->fd = -1;
 		sdi->status = SR_ST_INACTIVE;
 	}
 
@@ -737,7 +739,7 @@ static int config_list(int key, GVariant **data, const struct sr_dev_inst *sdi,
 
 static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
 {
-	struct sr_serial_dev_inst *serial;
+	struct sr_usbtmc_dev_inst *usbtmc;
 	struct dev_context *devc;
 	struct sr_probe *probe;
 	GSList *l;
@@ -746,7 +748,7 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
 	if (sdi->status != SR_ST_ACTIVE)
 		return SR_ERR_DEV_CLOSED;
 
-	serial = sdi->conn;
+	usbtmc = sdi->conn;
 	devc = sdi->priv;
 
 	if (devc->data_source == DATA_SOURCE_LIVE) {
@@ -792,7 +794,7 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
 	if (!devc->enabled_analog_probes && !devc->enabled_digital_probes)
 		return SR_ERR;
 
-	sr_source_add(serial->fd, G_IO_IN, 50, rigol_ds_receive, (void *)sdi);
+	sr_source_add(usbtmc->fd, G_IO_IN, 50, rigol_ds_receive, (void *)sdi);
 
 	/* Send header packet to the session bus. */
 	std_session_send_df_header(cb_data, LOG_PREFIX);
@@ -843,7 +845,7 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi, void *cb_data)
 static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data)
 {
 	struct dev_context *devc;
-	struct sr_serial_dev_inst *serial;
+	struct sr_usbtmc_dev_inst *usbtmc;
 
 	(void)cb_data;
 
@@ -858,8 +860,8 @@ static int dev_acquisition_stop(struct sr_dev_inst *sdi, void *cb_data)
 	g_slist_free(devc->enabled_digital_probes);
 	devc->enabled_analog_probes = NULL;
 	devc->enabled_digital_probes = NULL;
-	serial = sdi->conn;
-	sr_source_remove(serial->fd);
+	usbtmc = sdi->conn;
+	sr_source_remove(usbtmc->fd);
 
 	return SR_OK;
 }
diff --git a/hardware/rigol-ds/protocol.c b/hardware/rigol-ds/protocol.c
index afcbf4a2..e8f611bc 100644
--- a/hardware/rigol-ds/protocol.c
+++ b/hardware/rigol-ds/protocol.c
@@ -346,13 +346,13 @@ SR_PRIV int rigol_ds_channel_start(const struct sr_dev_inst *sdi)
 }
 
 /* Read the header of a data block */
-static int rigol_ds_read_header(struct sr_serial_dev_inst *serial)
+static int rigol_ds_read_header(struct sr_usbtmc_dev_inst *usbtmc)
 {
 	char start[3], length[10];
 	int len, tmp;
 
 	/* Read the hashsign and length digit. */
-	tmp = serial_read(serial, start, 2);
+	tmp = read(usbtmc->fd, start, 2);
 	start[2] = '\0';
 	if (tmp != 2)
 	{
@@ -367,7 +367,7 @@ static int rigol_ds_read_header(struct sr_serial_dev_inst *serial)
 	len = atoi(start + 1);
 
 	/* Read the data length. */
-	tmp = serial_read(serial, length, len);
+	tmp = read(usbtmc->fd, length, len);
 	length[len] = '\0';
 	if (tmp != len)
 	{
@@ -388,7 +388,7 @@ static int rigol_ds_read_header(struct sr_serial_dev_inst *serial)
 SR_PRIV int rigol_ds_receive(int fd, int revents, void *cb_data)
 {
 	struct sr_dev_inst *sdi;
-	struct sr_serial_dev_inst *serial;
+	struct sr_usbtmc_dev_inst *usbtmc;
 	struct dev_context *devc;
 	struct sr_datafeed_packet packet;
 	struct sr_datafeed_analog analog;
@@ -405,7 +405,7 @@ SR_PRIV int rigol_ds_receive(int fd, int revents, void *cb_data)
 	if (!(devc = sdi->priv))
 		return TRUE;
 
-	serial = sdi->conn;
+	usbtmc = sdi->conn;
 
 	if (revents == G_IO_IN) {
 		if (devc->model->protocol == PROTOCOL_IEEE488_2) {
@@ -442,7 +442,7 @@ SR_PRIV int rigol_ds_receive(int fd, int revents, void *cb_data)
 				sr_dbg("New block header expected");
 				if (rigol_ds_send(sdi, ":WAV:DATA?") != SR_OK)
 					return TRUE;
-				len = rigol_ds_read_header(serial);
+				len = rigol_ds_read_header(usbtmc);
 				if (len == -1)
 					return TRUE;
 				/* At slow timebases in live capture the DS2072
@@ -454,7 +454,7 @@ SR_PRIV int rigol_ds_receive(int fd, int revents, void *cb_data)
 				if (devc->data_source == DATA_SOURCE_LIVE
 				    && (unsigned)len < devc->num_frame_bytes) {
 					sr_dbg("Discarding short data block");
-					serial_read(serial, devc->buffer, len + 1);
+					read(usbtmc->fd, devc->buffer, len + 1);
 					return TRUE;
 				}
 				devc->num_block_bytes = len;
@@ -465,12 +465,12 @@ SR_PRIV int rigol_ds_receive(int fd, int revents, void *cb_data)
 		probe = devc->channel_frame;
 		if (devc->model->protocol == PROTOCOL_IEEE488_2) {
 			len = devc->num_block_bytes - devc->num_block_read;
-			len = serial_read(serial, devc->buffer,
+			len = read(usbtmc->fd, devc->buffer,
 					len < ACQ_BUFFER_SIZE ? len : ACQ_BUFFER_SIZE);
 		} else {
 			waveform_size = probe->type == SR_PROBE_ANALOG ?
 					DS1000_ANALOG_LIVE_WAVEFORM_SIZE : DIGITAL_WAVEFORM_SIZE;
-			len = serial_read(serial, devc->buffer, waveform_size - devc->num_frame_bytes);
+			len = read(usbtmc->fd, devc->buffer, waveform_size - devc->num_frame_bytes);
 		}
 		sr_dbg("Received %d bytes.", len);
 		if (len == -1)
@@ -510,7 +510,7 @@ SR_PRIV int rigol_ds_receive(int fd, int revents, void *cb_data)
 					sr_dbg("Block has been completed");
 					/* Discard the terminating linefeed and prepare for
 					   possible next block */
-					serial_read(serial, devc->buffer, 1);
+					read(usbtmc->fd, devc->buffer, 1);
 					devc->num_block_bytes = 0;
 					if (devc->data_source != DATA_SOURCE_LIVE)
 						rigol_ds_set_wait_event(devc, WAIT_BLOCK);
@@ -611,13 +611,14 @@ SR_PRIV int rigol_ds_send(const struct sr_dev_inst *sdi, const char *format, ...
 	va_list args;
 	char buf[256];
 	int len, out, ret;
+	struct sr_usbtmc_dev_inst *usbtmc = sdi->conn;
 
 	va_start(args, format);
 	len = vsnprintf(buf, 255, format, args);
 	va_end(args);
 	strcat(buf, "\n");
 	len++;
-	out = serial_write(sdi->conn, buf, len);
+	out = write(usbtmc->fd, buf, len);
 	buf[len - 1] = '\0';
 	if (out != len) {
 		sr_dbg("Only sent %d/%d bytes of '%s'.", out, len, buf);
@@ -634,11 +635,12 @@ static int get_cfg(const struct sr_dev_inst *sdi, char *cmd, char *reply, size_t
 {
 	int len;
 	struct dev_context *devc = sdi->priv;
+	struct sr_usbtmc_dev_inst *usbtmc = sdi->conn;
 
 	if (rigol_ds_send(sdi, cmd) != SR_OK)
 		return SR_ERR;
 
-	if ((len = serial_read(sdi->conn, reply, maxlen - 1)) < 0)
+	if ((len = read(usbtmc->fd, reply, maxlen - 1)) < 0)
 		return SR_ERR;
 	reply[len] = '\0';
 
diff --git a/libsigrok-internal.h b/libsigrok-internal.h
index f742e127..376e657e 100644
--- a/libsigrok-internal.h
+++ b/libsigrok-internal.h
@@ -79,6 +79,11 @@ struct sr_serial_dev_inst {
 };
 #endif
 
+struct sr_usbtmc_dev_inst {
+	char *device;
+	int fd;
+};
+
 /* Private driver context. */
 struct drv_context {
 	struct sr_context *sr_ctx;
@@ -119,6 +124,9 @@ SR_PRIV struct sr_serial_dev_inst *sr_serial_dev_inst_new(const char *port,
 SR_PRIV void sr_serial_dev_inst_free(struct sr_serial_dev_inst *serial);
 #endif
 
+/* USBTMC-specific instances */
+SR_PRIV struct sr_usbtmc_dev_inst *sr_usbtmc_dev_inst_new(const char *device);
+SR_PRIV void sr_usbtmc_dev_inst_free(struct sr_usbtmc_dev_inst *usbtmc);
 
 /*--- hwdriver.c ------------------------------------------------------------*/
 
diff --git a/libsigrok.h b/libsigrok.h
index f0f6d0cc..1e45a5e1 100644
--- a/libsigrok.h
+++ b/libsigrok.h
@@ -803,6 +803,8 @@ enum {
 	SR_INST_USB = 10000,
 	/** Device instance type for serial port devices. */
 	SR_INST_SERIAL,
+	/** Device instance type for USBTMC devices. */
+	SR_INST_USBTMC,
 };
 
 /** Device instance status. */
diff --git a/std.c b/std.c
index 44435be2..d1ff84e0 100644
--- a/std.c
+++ b/std.c
@@ -215,6 +215,8 @@ SR_PRIV int std_dev_clear(const struct sr_dev_driver *driver,
 			if (sdi->inst_type == SR_INST_USB)
 				sr_usb_dev_inst_free(sdi->conn);
 #endif
+			if (sdi->inst_type == SR_INST_USBTMC)
+				sr_usbtmc_dev_inst_free(sdi->conn);
 		}
 		if (clear_private)
 			clear_private(sdi->priv);