diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..10e3edd
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,56 @@
+language: c
+
+matrix:
+  include:
+    - os: linux
+      compiler: gcc
+
+    - os: linux
+      compiler: clang
+
+    - os: osx
+      compiler: gcc
+
+    - os: osx
+      compiler: clang
+
+    - os: linux
+      compiler: i686-w64-mingw32-gcc
+      addons:
+        apt:
+          packages:
+            - gcc-mingw-w64
+            - binutils-mingw-w64
+            - mingw-w64-tools
+
+    - os: linux
+      compiler: x86_64-w64-mingw32-gcc
+      addons:
+        apt:
+          packages:
+            - gcc-mingw-w64
+            - binutils-mingw-w64
+            - mingw-w64-tools
+
+addons:
+  apt:
+    packages:
+      - libbluetooth-dev
+      - libusb-1.0-0-dev
+
+install:
+  - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
+        brew install hidapi libusb;
+    fi
+
+script:
+  - case $CC in
+        *-gcc) TARGET="${CC%-gcc}" ;;
+    esac
+  - if [ -n "$TARGET" ]; then
+        TARGETOPTS="--host=${TARGET}";
+        unset CC;
+    fi
+  - autoreconf --install --force
+  - ./configure $TARGETOPTS --disable-doc
+  - make
diff --git a/doc/man/Makefile.am b/doc/man/Makefile.am
index fbaa991..7108446 100644
--- a/doc/man/Makefile.am
+++ b/doc/man/Makefile.am
@@ -14,6 +14,7 @@ MANPAGES = \
 	dc_datetime_mktime.3 \
 	dc_datetime_now.3 \
 	dc_descriptor_free.3 \
+	dc_descriptor_get_model.3 \
 	dc_descriptor_get_product.3 \
 	dc_descriptor_get_vendor.3 \
 	dc_descriptor_iterator.3 \
diff --git a/doc/man/dc_descriptor_get_model.3 b/doc/man/dc_descriptor_get_model.3
new file mode 100644
index 0000000..24ee991
--- /dev/null
+++ b/doc/man/dc_descriptor_get_model.3
@@ -0,0 +1,52 @@
+
+.\"
+.\" libdivecomputer
+.\"
+.\" Copyright (C) 2018 Kristaps Dzonsons <kristaps@bsd.lv>
+.\"
+.\" This library is free software; you can redistribute it and/or
+.\" modify it under the terms of the GNU Lesser General Public
+.\" License as published by the Free Software Foundation; either
+.\" version 2.1 of the License, or (at your option) any later version.
+.\"
+.\" This library is distributed in the hope that it will be useful,
+.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
+.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+.\" Lesser General Public License for more details.
+.\"
+.\" You should have received a copy of the GNU Lesser General Public
+.\" License along with this library; if not, write to the Free Software
+.\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+.\" MA 02110-1301 USA
+.\"
+.Dd August 19, 2018
+.Dt DC_DESCRIPTOR_GET_MODEL 3
+.Os
+.Sh NAME
+.Nm dc_descriptor_get_model
+.Nd get the model of a dive computer descriptor
+.Sh LIBRARY
+.Lb libdivecomputer
+.Sh SYNOPSIS
+.In libdivecomputer/descriptor.h
+.Ft "unsigned int"
+.Fo dc_descriptor_get_model
+.Fa "dc_descriptor_t *descriptor"
+.Fc
+.Sh DESCRIPTION
+Gets the model number of a dive computer descriptor or 0 if none was
+defined for the computer.
+0 is also a valid model number.
+.Sh RETURN VALUES
+This returns the model number or 0 if none exists.
+.Sh SEE ALSO
+.Xr dc_descriptor_iterator 3
+.Sh AUTHORS
+The
+.Lb libdivecomputer
+library was written by
+.An Jef Driesen ,
+.Mt jef@libdivecomputer.org .
+The manpages were written by
+.An Kristaps Dzonsons ,
+.Mt kristaps@bsd.lv .
diff --git a/examples/dctool_timesync.c b/examples/dctool_timesync.c
index e0aff1f..35647b1 100644
--- a/examples/dctool_timesync.c
+++ b/examples/dctool_timesync.c
@@ -123,6 +123,9 @@ dctool_timesync_run (int argc, char *argv[], dc_context_t *context, dc_descripto
 		case 'h':
 			help = 1;
 			break;
+		case 't':
+			transport = dctool_transport_type (optarg);
+			break;
 		default:
 			return EXIT_FAILURE;
 		}
diff --git a/include/libdivecomputer/iostream.h b/include/libdivecomputer/iostream.h
index e2cb439..d7d2621 100644
--- a/include/libdivecomputer/iostream.h
+++ b/include/libdivecomputer/iostream.h
@@ -22,6 +22,7 @@
 #ifndef DC_IOSTREAM_H
 #define DC_IOSTREAM_H
 
+#include <stddef.h>
 #include <libdivecomputer/common.h>
 #include <libdivecomputer/context.h>
 
diff --git a/src/descriptor.c b/src/descriptor.c
index 6871e1b..80fa734 100644
--- a/src/descriptor.c
+++ b/src/descriptor.c
@@ -208,6 +208,7 @@ static const dc_descriptor_t g_descriptors[] = {
 	{"Oceanic",  "OCi",                 DC_FAMILY_OCEANIC_ATOM2, 0x454B, DC_TRANSPORT_SERIAL, NULL},
 	{"Aeris",    "A300CS",              DC_FAMILY_OCEANIC_ATOM2, 0x454C, DC_TRANSPORT_SERIAL, NULL},
 	{"Beuchat",  "Mundial 3",           DC_FAMILY_OCEANIC_ATOM2, 0x4550, DC_TRANSPORT_SERIAL, NULL},
+	{"Oceanic",  "Pro Plus X",          DC_FAMILY_OCEANIC_ATOM2, 0x4552, DC_TRANSPORT_SERIAL, NULL},
 	{"Oceanic",  "F10",                 DC_FAMILY_OCEANIC_ATOM2, 0x4553, DC_TRANSPORT_SERIAL, NULL},
 	{"Oceanic",  "F11",                 DC_FAMILY_OCEANIC_ATOM2, 0x4554, DC_TRANSPORT_SERIAL, NULL},
 	{"Subgear",  "XP-Air",              DC_FAMILY_OCEANIC_ATOM2, 0x4555, DC_TRANSPORT_SERIAL, NULL},
@@ -245,6 +246,7 @@ static const dc_descriptor_t g_descriptors[] = {
 	{"Mares", "Nemo Wide 2",       DC_FAMILY_MARES_ICONHD , 0x19, DC_TRANSPORT_SERIAL, NULL},
 	{"Mares", "Puck 2",            DC_FAMILY_MARES_ICONHD , 0x1F, DC_TRANSPORT_SERIAL, NULL},
 	{"Mares", "Quad Air",          DC_FAMILY_MARES_ICONHD , 0x23, DC_TRANSPORT_SERIAL | DC_TRANSPORT_BLE, NULL},
+	{"Mares", "Smart Air",         DC_FAMILY_MARES_ICONHD , 0x24, DC_TRANSPORT_SERIAL | DC_TRANSPORT_BLE, NULL},
 	{"Mares", "Quad",              DC_FAMILY_MARES_ICONHD , 0x29, DC_TRANSPORT_SERIAL | DC_TRANSPORT_BLE, NULL},
 	/* Heinrichs Weikamp */
 	{"Heinrichs Weikamp", "OSTC",     DC_FAMILY_HW_OSTC, 0, DC_TRANSPORT_SERIAL, NULL},
diff --git a/src/hw_ostc_parser.c b/src/hw_ostc_parser.c
index f053a21..055c0f7 100644
--- a/src/hw_ostc_parser.c
+++ b/src/hw_ostc_parser.c
@@ -508,6 +508,8 @@ hw_ostc_parser_get_field (dc_parser_t *abstract, dc_field_type_t type, unsigned
 			*((double *) value) = array_uint16_le (data + layout->maxdepth) / 100.0;
 			break;
 		case DC_FIELD_AVGDEPTH:
+			if (parser->version < 0x21)
+				return DC_STATUS_UNSUPPORTED;
 			*((double *) value) = array_uint16_le (data + layout->avgdepth) / 100.0;
 			break;
 		case DC_FIELD_GASMIX_COUNT:
diff --git a/src/mares_iconhd.c b/src/mares_iconhd.c
index 450245e..d5f0ede 100644
--- a/src/mares_iconhd.c
+++ b/src/mares_iconhd.c
@@ -42,6 +42,7 @@
 #define NEMOWIDE2 0x19
 #define PUCK2     0x1F
 #define QUADAIR   0x23
+#define SMARTAIR  0x24
 #define QUAD      0x29
 
 #define ACK 0xAA
@@ -127,6 +128,7 @@ mares_iconhd_get_model (mares_iconhd_device_t *device)
 		{"Nemo Wide 2", NEMOWIDE2},
 		{"Puck 2",      PUCK2},
 		{"Quad Air",    QUADAIR},
+		{"Smart Air",   SMARTAIR},
 		{"Quad",        QUAD},
 	};
 
@@ -293,6 +295,7 @@ mares_iconhd_device_open (dc_device_t **out, dc_context_t *context, dc_iostream_
 		device->packetsize = 256;
 		break;
 	case QUADAIR:
+	case SMARTAIR:
 		device->layout = &mares_iconhdnet_layout;
 		device->packetsize = 256;
 		break;
@@ -442,7 +445,7 @@ mares_iconhd_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback,
 		header = 0x80;
 	else if (model == QUADAIR)
 		header = 0x84;
-	else if (model == SMART)
+	else if (model == SMART || model == SMARTAIR)
 		header = 4; // Type and number of samples only!
 	else if (model == SMARTAPNEA)
 		header = 6; // Type and number of samples only!
@@ -504,7 +507,7 @@ mares_iconhd_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback,
 
 		// Get the number of samples in the profile data.
 		unsigned int type = 0, nsamples = 0;
-		if (model == SMART || model == SMARTAPNEA) {
+		if (model == SMART || model == SMARTAPNEA || model == SMARTAIR) {
 			type     = array_uint16_le (buffer + offset - header + 2);
 			nsamples = array_uint16_le (buffer + offset - header + 0);
 		} else {
@@ -541,6 +544,10 @@ mares_iconhd_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback,
 			headersize = 0x50;
 			samplesize = 14;
 			fingerprint = 0x40;
+		} else if (model == SMARTAIR) {
+			headersize = 0x84;
+			samplesize = 12;
+			fingerprint = 2;
 		}
 		if (offset < headersize)
 			break;
@@ -559,7 +566,7 @@ mares_iconhd_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback,
 		// end of the ringbuffer. The current dive is incomplete (partially
 		// overwritten with newer data), and processing should stop.
 		unsigned int nbytes = 4 + headersize + nsamples * samplesize;
-		if (model == ICONHDNET || model == QUADAIR) {
+		if (model == ICONHDNET || model == QUADAIR || model == SMARTAIR) {
 			nbytes += (nsamples / 4) * 8;
 		} else if (model == SMARTAPNEA) {
 			unsigned int settings = array_uint16_le (buffer + offset - headersize + 0x1C);
diff --git a/src/mares_iconhd_parser.c b/src/mares_iconhd_parser.c
index 0c48a22..aa44ace 100644
--- a/src/mares_iconhd_parser.c
+++ b/src/mares_iconhd_parser.c
@@ -35,6 +35,7 @@
 #define ICONHD    0x14
 #define ICONHDNET 0x15
 #define QUADAIR   0x23
+#define SMARTAIR  0x24
 
 #define NGASMIXES 3
 #define NTANKS    NGASMIXES
@@ -94,7 +95,7 @@ mares_iconhd_parser_cache (mares_iconhd_parser_t *parser)
 		header = 0x80;
 	else if (parser->model == QUADAIR)
 		header = 0x84;
-	else if (parser->model == SMART)
+	else if (parser->model == SMART || parser->model == SMARTAIR)
 		header = 4; // Type and number of samples only!
 	else if (parser->model == SMARTAPNEA)
 		header = 6; // Type and number of samples only!
@@ -112,7 +113,7 @@ mares_iconhd_parser_cache (mares_iconhd_parser_t *parser)
 
 	// Get the number of samples in the profile data.
 	unsigned int type = 0, nsamples = 0;
-	if (parser->model == SMART || parser->model == SMARTAPNEA) {
+	if (parser->model == SMART || parser->model == SMARTAPNEA || parser->model == SMARTAIR) {
 		type     = array_uint16_le (data + length - header + 2);
 		nsamples = array_uint16_le (data + length - header + 0);
 	} else {
@@ -129,7 +130,7 @@ mares_iconhd_parser_cache (mares_iconhd_parser_t *parser)
 	if (parser->model == ICONHDNET) {
 		headersize = 0x80;
 		samplesize = 12;
-	} else if (parser->model == QUADAIR) {
+	} else if (parser->model == QUADAIR || parser->model == SMARTAIR) {
 		headersize = 0x84;
 		samplesize = 12;
 	} else if (parser->model == SMART) {
@@ -151,7 +152,7 @@ mares_iconhd_parser_cache (mares_iconhd_parser_t *parser)
 	}
 
 	const unsigned char *p = data + length - headersize;
-	if (parser->model != SMART && parser->model != SMARTAPNEA) {
+	if (parser->model != SMART && parser->model != SMARTAPNEA && parser->model != SMARTAIR) {
 		p += 4;
 	}
 
@@ -181,7 +182,7 @@ mares_iconhd_parser_cache (mares_iconhd_parser_t *parser)
 
 	// Calculate the total number of bytes for this dive.
 	unsigned int nbytes = 4 + headersize + nsamples * samplesize;
-	if (parser->model == ICONHDNET || parser->model == QUADAIR) {
+	if (parser->model == ICONHDNET || parser->model == QUADAIR || parser->model == SMARTAIR) {
 		nbytes += (nsamples / 4) * 8;
 	} else if (parser->model == SMARTAPNEA) {
 		unsigned int divetime = array_uint32_le (p + 0x24);
@@ -215,7 +216,7 @@ mares_iconhd_parser_cache (mares_iconhd_parser_t *parser)
 
 	// Tanks
 	unsigned int ntanks = 0;
-	if (parser->model == ICONHDNET || parser->model == QUADAIR) {
+	if (parser->model == ICONHDNET || parser->model == QUADAIR || parser->model == SMARTAIR) {
 		unsigned int tankoffset = (parser->model == ICONHDNET) ? 0x58 : 0x5C;
 		while (ntanks < NTANKS) {
 			unsigned int beginpressure = array_uint16_le (p + tankoffset + ntanks * 4 + 0);
@@ -325,6 +326,8 @@ mares_iconhd_parser_get_datetime (dc_parser_t *abstract, dc_datetime_t *datetime
 		}
 	} else if (parser->model == SMARTAPNEA) {
 		p += 0x40;
+	} else if (parser->model == SMARTAIR) {
+		p += 2;
 	} else {
 		p += 6;
 	}
@@ -354,7 +357,7 @@ mares_iconhd_parser_get_field (dc_parser_t *abstract, dc_field_type_t type, unsi
 		return rc;
 
 	const unsigned char *p = abstract->data + parser->footer;
-	if (parser->model != SMART && parser->model != SMARTAPNEA) {
+	if (parser->model != SMART && parser->model != SMARTAPNEA && parser->model != SMARTAIR) {
 		p += 4;
 	}
 
@@ -611,7 +614,8 @@ mares_iconhd_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_t
 			nsamples++;
 
 			// Some extra data.
-			if ((parser->model == ICONHDNET || parser->model == QUADAIR) && (nsamples % 4) == 0) {
+			if ((parser->model == ICONHDNET || parser->model == QUADAIR || parser->model == SMARTAIR) &&
+				(nsamples % 4) == 0) {
 				// Pressure (1/100 bar).
 				unsigned int pressure = array_uint16_le(data + offset);
 				if (gasmix < parser->ntanks) {
diff --git a/src/oceanic_atom2.c b/src/oceanic_atom2.c
index f7a9b7a..c33c880 100644
--- a/src/oceanic_atom2.c
+++ b/src/oceanic_atom2.c
@@ -32,6 +32,7 @@
 
 #define ISINSTANCE(device) dc_device_isinstance((device), &oceanic_atom2_device_vtable.base)
 
+#define PROPLUSX   0x4552
 #define VTX        0x4557
 #define I750TC     0x455A
 
@@ -44,6 +45,7 @@
 #define CMD_READ1     0xB1
 #define CMD_READ8     0xB4
 #define CMD_READ16    0xB8
+#define CMD_READ16HI  0xF6
 #define CMD_WRITE     0xB2
 #define CMD_KEEPALIVE 0x91
 #define CMD_QUIT      0x6A
@@ -57,7 +59,8 @@ typedef struct oceanic_atom2_device_t {
 	unsigned int delay;
 	unsigned int bigpage;
 	unsigned char cache[256];
-	unsigned int cached;
+	unsigned int cached_page;
+	unsigned int cached_highmem;
 } oceanic_atom2_device_t;
 
 static dc_status_t oceanic_atom2_device_read (dc_device_t *abstract, unsigned int address, unsigned char data[], unsigned int size);
@@ -184,6 +187,10 @@ static const oceanic_common_version_t oceanic_reactpro_version[] = {
 	{"REACPRO2 \0\0 512K"},
 };
 
+static const oceanic_common_version_t oceanic_proplusx_version[] = {
+	{"OCEANOCX \0\0 2048"},
+};
+
 static const oceanic_common_version_t aeris_a300cs_version[] = {
 	{"AER300CS \0\0 2048"},
 	{"OCEANVTX \0\0 2048"},
@@ -196,6 +203,7 @@ static const oceanic_common_version_t aqualung_i450t_version[] = {
 
 static const oceanic_common_layout_t aeris_f10_layout = {
 	0x10000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0100, /* rb_logbook_begin */
@@ -210,6 +218,7 @@ static const oceanic_common_layout_t aeris_f10_layout = {
 
 static const oceanic_common_layout_t aeris_f11_layout = {
 	0x20000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0100, /* rb_logbook_begin */
@@ -224,6 +233,7 @@ static const oceanic_common_layout_t aeris_f11_layout = {
 
 static const oceanic_common_layout_t oceanic_default_layout = {
 	0x10000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -238,6 +248,7 @@ static const oceanic_common_layout_t oceanic_default_layout = {
 
 static const oceanic_common_layout_t oceanic_atom1_layout = {
 	0x8000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -252,6 +263,7 @@ static const oceanic_common_layout_t oceanic_atom1_layout = {
 
 static const oceanic_common_layout_t oceanic_atom2a_layout = {
 	0xFFF0, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -266,6 +278,7 @@ static const oceanic_common_layout_t oceanic_atom2a_layout = {
 
 static const oceanic_common_layout_t oceanic_atom2b_layout = {
 	0x10000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -280,6 +293,7 @@ static const oceanic_common_layout_t oceanic_atom2b_layout = {
 
 static const oceanic_common_layout_t oceanic_atom2c_layout = {
 	0xFFF0, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -294,6 +308,7 @@ static const oceanic_common_layout_t oceanic_atom2c_layout = {
 
 static const oceanic_common_layout_t sherwood_wisdom_layout = {
 	0xFFF0, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x03D0, /* rb_logbook_begin */
@@ -308,6 +323,7 @@ static const oceanic_common_layout_t sherwood_wisdom_layout = {
 
 static const oceanic_common_layout_t oceanic_proplus3_layout = {
 	0x10000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x03E0, /* rb_logbook_begin */
@@ -322,6 +338,7 @@ static const oceanic_common_layout_t oceanic_proplus3_layout = {
 
 static const oceanic_common_layout_t tusa_zenair_layout = {
 	0xFFF0, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -336,6 +353,7 @@ static const oceanic_common_layout_t tusa_zenair_layout = {
 
 static const oceanic_common_layout_t oceanic_oc1_layout = {
 	0x20000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -350,6 +368,7 @@ static const oceanic_common_layout_t oceanic_oc1_layout = {
 
 static const oceanic_common_layout_t oceanic_oci_layout = {
 	0x20000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x10C0, /* rb_logbook_begin */
@@ -364,6 +383,7 @@ static const oceanic_common_layout_t oceanic_oci_layout = {
 
 static const oceanic_common_layout_t oceanic_atom3_layout = {
 	0x20000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0400, /* rb_logbook_begin */
@@ -378,6 +398,7 @@ static const oceanic_common_layout_t oceanic_atom3_layout = {
 
 static const oceanic_common_layout_t oceanic_vt4_layout = {
 	0x20000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0420, /* rb_logbook_begin */
@@ -392,6 +413,7 @@ static const oceanic_common_layout_t oceanic_vt4_layout = {
 
 static const oceanic_common_layout_t hollis_tx1_layout = {
 	0x40000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0780, /* rb_logbook_begin */
@@ -406,6 +428,7 @@ static const oceanic_common_layout_t hollis_tx1_layout = {
 
 static const oceanic_common_layout_t oceanic_veo1_layout = {
 	0x0400, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0400, /* rb_logbook_begin */
@@ -420,6 +443,7 @@ static const oceanic_common_layout_t oceanic_veo1_layout = {
 
 static const oceanic_common_layout_t oceanic_reactpro_layout = {
 	0xFFF0, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0400, /* rb_logbook_begin */
@@ -432,8 +456,24 @@ static const oceanic_common_layout_t oceanic_reactpro_layout = {
 	1, /* pt_mode_serial */
 };
 
+static const oceanic_common_layout_t oceanic_proplusx_layout = {
+	0x440000, /* memsize */
+	0x40000, /* highmem */
+	0x0000, /* cf_devinfo */
+	0x0040, /* cf_pointers */
+	0x1000, /* rb_logbook_begin */
+	0x10000, /* rb_logbook_end */
+	16, /* rb_logbook_entry_size */
+	0x40000, /* rb_profile_begin */
+	0x440000, /* rb_profile_end */
+	0, /* pt_mode_global */
+	1, /* pt_mode_logbook */
+	0, /* pt_mode_serial */
+};
+
 static const oceanic_common_layout_t aeris_a300cs_layout = {
 	0x40000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0900, /* rb_logbook_begin */
@@ -448,6 +488,7 @@ static const oceanic_common_layout_t aeris_a300cs_layout = {
 
 static const oceanic_common_layout_t aqualung_i450t_layout = {
 	0x40000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x10C0, /* rb_logbook_begin */
@@ -595,12 +636,13 @@ oceanic_atom2_device_open (dc_device_t **out, dc_context_t *context, dc_iostream
 	device->iostream = iostream;
 	device->delay = 0;
 	device->bigpage = 1; // no big pages
-	device->cached = INVALID;
+	device->cached_page = INVALID;
+	device->cached_highmem = INVALID;
 	memset(device->cache, 0, sizeof(device->cache));
 
 	// Get the correct baudrate.
 	unsigned int baudrate = 38400;
-	if (model == VTX || model == I750TC) {
+	if (model == VTX || model == I750TC || model == PROPLUSX) {
 		baudrate = 115200;
 	}
 
@@ -684,6 +726,9 @@ oceanic_atom2_device_open (dc_device_t **out, dc_context_t *context, dc_iostream
 		device->base.layout = &oceanic_veo1_layout;
 	} else if (OCEANIC_COMMON_MATCH (device->base.version, oceanic_reactpro_version)) {
 		device->base.layout = &oceanic_reactpro_layout;
+	} else if (OCEANIC_COMMON_MATCH (device->base.version, oceanic_proplusx_version)) {
+		device->base.layout = &oceanic_proplusx_layout;
+		device->bigpage = 16;
 	} else if (OCEANIC_COMMON_MATCH (device->base.version, aeris_a300cs_version)) {
 		device->base.layout = &aeris_a300cs_layout;
 		device->bigpage = 16;
@@ -779,6 +824,7 @@ static dc_status_t
 oceanic_atom2_device_read (dc_device_t *abstract, unsigned int address, unsigned char data[], unsigned int size)
 {
 	oceanic_atom2_device_t *device = (oceanic_atom2_device_t*) abstract;
+	const oceanic_common_layout_t *layout = device->base.layout;
 
 	if ((address % PAGESIZE != 0) ||
 		(size    % PAGESIZE != 0))
@@ -807,12 +853,26 @@ oceanic_atom2_device_read (dc_device_t *abstract, unsigned int address, unsigned
 	// Pick the best pagesize to use.
 	unsigned int pagesize = device->bigpage * PAGESIZE;
 
+	// High memory state.
+	unsigned int highmem = 0;
+
 	unsigned int nbytes = 0;
 	while (nbytes < size) {
-		unsigned int page = address / pagesize;
-		if (page != device->cached) {
+		// Switch to the correct read command when entering the high memory area.
+		if (layout->highmem && address >= layout->highmem && !highmem) {
+			highmem = layout->highmem;
+			read_cmd = CMD_READ16HI;
+			crc_size = 2;
+			pagesize = 16 * PAGESIZE;
+		}
+
+		// Calculate the page number after mapping the virtual high memory
+		// addresses back to their physical address.
+		unsigned int page = (address - highmem) / pagesize;
+
+		if (page != device->cached_page || highmem != device->cached_highmem) {
 			// Read the package.
-			unsigned int number = page * device->bigpage; // This is always PAGESIZE, even in big page mode.
+			unsigned int number = highmem ? page : page * device->bigpage; // This is always PAGESIZE, even in big page mode.
 			unsigned char answer[256 + 2] = {0};          // Maximum we support for the known commands.
 			unsigned char command[4] = {read_cmd,
 					(number >> 8) & 0xFF, // high
@@ -824,7 +884,8 @@ oceanic_atom2_device_read (dc_device_t *abstract, unsigned int address, unsigned
 
 			// Cache the page.
 			memcpy (device->cache, answer, pagesize);
-			device->cached = page;
+			device->cached_page = page;
+			device->cached_highmem = highmem;
 		}
 
 		unsigned int offset = address % pagesize;
@@ -853,7 +914,8 @@ oceanic_atom2_device_write (dc_device_t *abstract, unsigned int address, const u
 		return DC_STATUS_INVALIDARGS;
 
 	// Invalidate the cache.
-	device->cached = INVALID;
+	device->cached_page = INVALID;
+	device->cached_highmem = INVALID;
 
 	unsigned int nbytes = 0;
 	while (nbytes < size) {
diff --git a/src/oceanic_atom2_parser.c b/src/oceanic_atom2_parser.c
index 444ed1e..0a2f7c2 100644
--- a/src/oceanic_atom2_parser.c
+++ b/src/oceanic_atom2_parser.c
@@ -77,6 +77,7 @@
 #define OCI         0x454B
 #define A300CS      0x454C
 #define MUNDIAL3    0x4550
+#define PROPLUSX    0x4552
 #define F10B        0x4553
 #define F11B        0x4554
 #define XPAIR       0x4555
@@ -177,6 +178,8 @@ oceanic_atom2_parser_create (dc_parser_t **out, dc_context_t *context, unsigned
 	} else if (model == A300CS || model == VTX ||
 		model == I450T || model == I750TC) {
 		parser->headersize = 5 * PAGESIZE;
+	} else if (model == PROPLUSX) {
+		parser->headersize = 3 * PAGESIZE;
 	}
 
 	parser->serial = serial;
@@ -313,6 +316,7 @@ oceanic_atom2_parser_get_datetime (dc_parser_t *abstract, dc_datetime_t *datetim
 		case VTX:
 		case I450T:
 		case I750TC:
+		case PROPLUSX:
 			datetime->year   = (p[10]) + 2000;
 			datetime->month  = (p[8]);
 			datetime->day    = (p[9]);
@@ -641,7 +645,8 @@ oceanic_atom2_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_
 	if (parser->mode != FREEDIVE) {
 		unsigned int idx = 0x17;
 		if (parser->model == A300CS || parser->model == VTX ||
-			parser->model == I450T || parser->model == I750TC)
+			parser->model == I450T || parser->model == I750TC ||
+			parser->model == PROPLUSX)
 			idx = 0x1f;
 		switch (data[idx] & 0x03) {
 		case 0:
@@ -696,7 +701,7 @@ oceanic_atom2_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_
 		parser->model == OC1C || parser->model == OCI ||
 		parser->model == TX1 || parser->model == A300CS ||
 		parser->model == VTX || parser->model == I450T ||
-		parser->model == I750TC) {
+		parser->model == I750TC || parser->model == PROPLUSX) {
 		samplesize = PAGESIZE;
 	}
 
@@ -874,7 +879,7 @@ oceanic_atom2_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_
 					parser->model == XPAIR) {
 					temperature = ((data[offset + 7] & 0xF0) >> 4) | ((data[offset + 7] & 0x0C) << 2) | ((data[offset + 5] & 0x0C) << 4);
 				} else if (parser->model == A300CS || parser->model == VTX ||
-					parser->model == I750TC) {
+					parser->model == I750TC || parser->model == PROPLUSX) {
 					temperature = data[offset + 11];
 				} else {
 					unsigned int sign;
@@ -914,7 +919,8 @@ oceanic_atom2_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_
 					parser->model == VISION || parser->model == XPAIR)
 					pressure = (((data[offset + 0] & 0x03) << 8) + data[offset + 1]) * 5;
 				else if (parser->model == TX1 || parser->model == A300CS ||
-					parser->model == VTX || parser->model == I750TC)
+					parser->model == VTX || parser->model == I750TC ||
+					parser->model == PROPLUSX)
 					pressure = array_uint16_le (data + offset + 4);
 				else
 					pressure -= data[offset + 1];
@@ -962,7 +968,8 @@ oceanic_atom2_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_
 			unsigned int have_deco = 0;
 			unsigned int decostop = 0, decotime = 0;
 			if (parser->model == A300CS || parser->model == VTX ||
-				parser->model == I450T || parser->model == I750TC) {
+				parser->model == I450T || parser->model == I750TC ||
+				parser->model == PROPLUSX) {
 				decostop = (data[offset + 15] & 0x70) >> 4;
 				decotime = array_uint16_le(data + offset + 6) & 0x03FF;
 				have_deco = 1;
@@ -1005,7 +1012,7 @@ oceanic_atom2_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callback_
 				have_rbt = 1;
 			} else if (parser->model == I450T || parser->model == OC1A ||
 				parser->model == OC1B || parser->model == OC1C ||
-				parser->model == OCI) {
+				parser->model == OCI || parser->model == PROPLUSX) {
 				rbt = array_uint16_le(data + offset + 8) & 0x01FF;
 				have_rbt = 1;
 			} else if (parser->model == VISION || parser->model == XPAIR ||
diff --git a/src/oceanic_common.c b/src/oceanic_common.c
index 9f7341a..908896c 100644
--- a/src/oceanic_common.c
+++ b/src/oceanic_common.c
@@ -41,7 +41,7 @@
 #define INVALID 0
 
 static unsigned int
-get_profile_first (const unsigned char data[], const oceanic_common_layout_t *layout)
+get_profile_first (const unsigned char data[], const oceanic_common_layout_t *layout, unsigned int pagesize)
 {
 	unsigned int value;
 
@@ -55,17 +55,22 @@ get_profile_first (const unsigned char data[], const oceanic_common_layout_t *la
 		return array_uint16_le (data + 16);
 	}
 
-	if (layout->memsize > 0x20000)
-		return (value & 0x3FFF) * PAGESIZE;
-	else if (layout->memsize > 0x10000)
-		return (value & 0x1FFF) * PAGESIZE;
-	else
-		return (value & 0x0FFF) * PAGESIZE;
+	unsigned int npages = (layout->memsize - layout->highmem) / pagesize;
+
+	if (npages > 0x2000) {
+		value &= 0x3FFF;
+	}  else if (npages > 0x1000) {
+		value &= 0x1FFF;
+	} else {
+		value &= 0x0FFF;
+	}
+
+	return layout->highmem + value * pagesize;
 }
 
 
 static unsigned int
-get_profile_last (const unsigned char data[], const oceanic_common_layout_t *layout)
+get_profile_last (const unsigned char data[], const oceanic_common_layout_t *layout, unsigned int pagesize)
 {
 	unsigned int value;
 
@@ -79,12 +84,17 @@ get_profile_last (const unsigned char data[], const oceanic_common_layout_t *lay
 		return array_uint16_le(data + 18);
 	}
 
-	if (layout->memsize > 0x20000)
-		return (value & 0x3FFF) * PAGESIZE;
-	else if (layout->memsize > 0x10000)
-		return (value & 0x1FFF) * PAGESIZE;
-	else
-		return (value & 0x0FFF) * PAGESIZE;
+	unsigned int npages = (layout->memsize - layout->highmem) / pagesize;
+
+	if (npages > 0x2000) {
+		value &= 0x3FFF;
+	} else if (npages > 0x1000) {
+		value &= 0x1FFF;
+	} else {
+		value &= 0x0FFF;
+	}
+
+	return layout->highmem + value * pagesize;
 }
 
 
@@ -330,6 +340,9 @@ oceanic_common_device_profile (dc_device_t *abstract, dc_event_progress_t *progr
 
 	const oceanic_common_layout_t *layout = device->layout;
 
+	// Get the pagesize
+	unsigned int pagesize = layout->highmem ? 16 * PAGESIZE : PAGESIZE;
+
 	// Cache the logbook pointer and size.
 	const unsigned char *logbooks = dc_buffer_get_data (logbook);
 	unsigned int rb_logbook_size = dc_buffer_get_size (logbook);
@@ -352,8 +365,8 @@ oceanic_common_device_profile (dc_device_t *abstract, dc_event_progress_t *progr
 		entry -= layout->rb_logbook_entry_size;
 
 		// Get the profile pointers.
-		unsigned int rb_entry_first = get_profile_first (logbooks + entry, layout);
-		unsigned int rb_entry_last  = get_profile_last (logbooks + entry, layout);
+		unsigned int rb_entry_first = get_profile_first (logbooks + entry, layout, pagesize);
+		unsigned int rb_entry_last  = get_profile_last (logbooks + entry, layout, pagesize);
 		if (rb_entry_first < layout->rb_profile_begin ||
 			rb_entry_first >= layout->rb_profile_end ||
 			rb_entry_last < layout->rb_profile_begin ||
@@ -365,8 +378,8 @@ oceanic_common_device_profile (dc_device_t *abstract, dc_event_progress_t *progr
 		}
 
 		// Calculate the end pointer and the number of bytes.
-		unsigned int rb_entry_end   = RB_PROFILE_INCR (rb_entry_last, PAGESIZE, layout);
-		unsigned int rb_entry_size  = RB_PROFILE_DISTANCE (rb_entry_first, rb_entry_last, layout) + PAGESIZE;
+		unsigned int rb_entry_end   = RB_PROFILE_INCR (rb_entry_last, pagesize, layout);
+		unsigned int rb_entry_size  = RB_PROFILE_DISTANCE (rb_entry_first, rb_entry_last, layout) + pagesize;
 
 		// Take the end pointer of the most recent logbook entry as the
 		// end of profile pointer.
@@ -430,8 +443,8 @@ oceanic_common_device_profile (dc_device_t *abstract, dc_event_progress_t *progr
 		entry -= layout->rb_logbook_entry_size;
 
 		// Get the profile pointers.
-		unsigned int rb_entry_first = get_profile_first (logbooks + entry, layout);
-		unsigned int rb_entry_last  = get_profile_last (logbooks + entry, layout);
+		unsigned int rb_entry_first = get_profile_first (logbooks + entry, layout, pagesize);
+		unsigned int rb_entry_last  = get_profile_last (logbooks + entry, layout, pagesize);
 		if (rb_entry_first < layout->rb_profile_begin ||
 			rb_entry_first >= layout->rb_profile_end ||
 			rb_entry_last < layout->rb_profile_begin ||
@@ -445,8 +458,8 @@ oceanic_common_device_profile (dc_device_t *abstract, dc_event_progress_t *progr
 		}
 
 		// Calculate the end pointer and the number of bytes.
-		unsigned int rb_entry_end   = RB_PROFILE_INCR (rb_entry_last, PAGESIZE, layout);
-		unsigned int rb_entry_size  = RB_PROFILE_DISTANCE (rb_entry_first, rb_entry_last, layout) + PAGESIZE;
+		unsigned int rb_entry_end   = RB_PROFILE_INCR (rb_entry_last, pagesize, layout);
+		unsigned int rb_entry_size  = RB_PROFILE_DISTANCE (rb_entry_first, rb_entry_last, layout) + pagesize;
 
 		// Skip gaps between the profiles.
 		unsigned int gap = 0;
@@ -481,6 +494,14 @@ oceanic_common_device_profile (dc_device_t *abstract, dc_event_progress_t *progr
 		offset -= layout->rb_logbook_entry_size;
 		memcpy (profiles + offset, logbooks + entry, layout->rb_logbook_entry_size);
 
+		// Remove padding from the profile.
+		if (layout->highmem) {
+			unsigned char *profile = profiles + offset + layout->rb_logbook_entry_size;
+			while (rb_entry_size >= PAGESIZE && array_isequal (profile + rb_entry_size - PAGESIZE, PAGESIZE, 0xFF)) {
+				rb_entry_size -= PAGESIZE;
+			}
+		}
+
 		unsigned char *p = profiles + offset;
 		if (callback && !callback (p, rb_entry_size + layout->rb_logbook_entry_size, p, layout->rb_logbook_entry_size, userdata)) {
 			break;
diff --git a/src/oceanic_common.h b/src/oceanic_common.h
index 1b8ed08..a5c55b8 100644
--- a/src/oceanic_common.h
+++ b/src/oceanic_common.h
@@ -38,6 +38,7 @@ extern "C" {
 typedef struct oceanic_common_layout_t {
 	// Memory size.
 	unsigned int memsize;
+	unsigned int highmem;
 	// Device info.
 	unsigned int cf_devinfo;
 	// Ringbuffer pointers.
diff --git a/src/oceanic_veo250.c b/src/oceanic_veo250.c
index 42cb676..de70c7b 100644
--- a/src/oceanic_veo250.c
+++ b/src/oceanic_veo250.c
@@ -75,6 +75,7 @@ static const oceanic_common_version_t oceanic_veo250_version[] = {
 
 static const oceanic_common_layout_t oceanic_veo250_layout = {
 	0x8000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0400, /* rb_logbook_begin */
diff --git a/src/oceanic_vtpro.c b/src/oceanic_vtpro.c
index 2c9298b..d3387f2 100644
--- a/src/oceanic_vtpro.c
+++ b/src/oceanic_vtpro.c
@@ -89,6 +89,7 @@ static const oceanic_common_version_t oceanic_wisdom_version[] = {
 
 static const oceanic_common_layout_t oceanic_vtpro_layout = {
 	0x8000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x0240, /* rb_logbook_begin */
@@ -103,6 +104,7 @@ static const oceanic_common_layout_t oceanic_vtpro_layout = {
 
 static const oceanic_common_layout_t oceanic_wisdom_layout = {
 	0x8000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0040, /* cf_pointers */
 	0x03D0, /* rb_logbook_begin */
@@ -117,6 +119,7 @@ static const oceanic_common_layout_t oceanic_wisdom_layout = {
 
 static const oceanic_common_layout_t aeris_500ai_layout = {
 	0x20000, /* memsize */
+	0, /* highmem */
 	0x0000, /* cf_devinfo */
 	0x0110, /* cf_pointers */
 	0x0200, /* rb_logbook_begin */