diff --git a/src/descriptor.c b/src/descriptor.c
index b59ea45..9ae3e77 100644
--- a/src/descriptor.c
+++ b/src/descriptor.c
@@ -231,6 +231,7 @@ static const dc_descriptor_t g_descriptors[] = {
 	{"Mares", "Puck Pro",          DC_FAMILY_MARES_ICONHD , 0x18},
 	{"Mares", "Nemo Wide 2",       DC_FAMILY_MARES_ICONHD , 0x19},
 	{"Mares", "Puck 2",            DC_FAMILY_MARES_ICONHD , 0x1F},
+	{"Mares", "Quad",              DC_FAMILY_MARES_ICONHD , 0x29},
 	/* Heinrichs Weikamp */
 	{"Heinrichs Weikamp", "OSTC",     DC_FAMILY_HW_OSTC, 0},
 	{"Heinrichs Weikamp", "OSTC Mk2", DC_FAMILY_HW_OSTC, 1},
@@ -290,8 +291,15 @@ static const dc_descriptor_t g_descriptors[] = {
 	{"DiveSystem", "iDive Deep",    DC_FAMILY_DIVESYSTEM_IDIVE, 0x0B},
 	{"DiveSystem", "iX3M Easy",     DC_FAMILY_DIVESYSTEM_IDIVE, 0x22},
 	{"DiveSystem", "iX3M Deep",     DC_FAMILY_DIVESYSTEM_IDIVE, 0x23},
-	{"DiveSystem", "iX3M Tec",      DC_FAMILY_DIVESYSTEM_IDIVE, 0x24},
+	{"DiveSystem", "iX3M Tech+",    DC_FAMILY_DIVESYSTEM_IDIVE, 0x24},
 	{"DiveSystem", "iX3M Reb",      DC_FAMILY_DIVESYSTEM_IDIVE, 0x25},
+	{"DiveSystem", "iX3M Pro Easy",  DC_FAMILY_DIVESYSTEM_IDIVE, 0x32},
+	{"DiveSystem", "iX3M Pro Deep",  DC_FAMILY_DIVESYSTEM_IDIVE, 0x34},
+	{"DiveSystem", "iX3M Pro Tech+", DC_FAMILY_DIVESYSTEM_IDIVE, 0x35},
+	{"DiveSystem", "iDive2 Free",    DC_FAMILY_DIVESYSTEM_IDIVE, 0x40},
+	{"DiveSystem", "iDive2 Easy",    DC_FAMILY_DIVESYSTEM_IDIVE, 0x42},
+	{"DiveSystem", "iDive2 Deep",    DC_FAMILY_DIVESYSTEM_IDIVE, 0x44},
+	{"DiveSystem", "iDive2 Tech+",   DC_FAMILY_DIVESYSTEM_IDIVE, 0x45},
 	{"Cochran", "Commander",	DC_FAMILY_COCHRAN_COMMANDER, 0},
 	{"Cochran", "EMC-14",		DC_FAMILY_COCHRAN_COMMANDER, 1},
 	{"Cochran", "EMC-16",		DC_FAMILY_COCHRAN_COMMANDER, 2},
diff --git a/src/divesystem_idive.c b/src/divesystem_idive.c
index d8c02e8..e2a5cda 100644
--- a/src/divesystem_idive.c
+++ b/src/divesystem_idive.c
@@ -57,6 +57,7 @@ typedef struct divesystem_idive_commands_t {
 	divesystem_idive_command_t range;
 	divesystem_idive_command_t header;
 	divesystem_idive_command_t sample;
+	unsigned int nsamples;
 } divesystem_idive_commands_t;
 
 typedef struct divesystem_idive_device_t {
@@ -86,6 +87,7 @@ static const divesystem_idive_commands_t idive = {
 	{0x98, 0x04},
 	{0xA0, 0x32},
 	{0xA8, 0x2A},
+	1,
 };
 
 static const divesystem_idive_commands_t ix3m = {
@@ -93,6 +95,15 @@ static const divesystem_idive_commands_t ix3m = {
 	{0x78, 0x04},
 	{0x79, 0x36},
 	{0x7A, 0x36},
+	1,
+};
+
+static const divesystem_idive_commands_t ix3m_apos4 = {
+	{0x11, 0x1A},
+	{0x78, 0x04},
+	{0x79, 0x36},
+	{0x7A, 0x40},
+	3,
 };
 
 dc_status_t
@@ -356,7 +367,7 @@ divesystem_idive_device_foreach (dc_device_t *abstract, dc_dive_callback_t callb
 	unsigned char packet[MAXPACKET - 2];
 
 	const divesystem_idive_commands_t *commands = &idive;
-	if (device->model >= IX3M_EASY && device->model <= IX3M_REB) {
+	if (device->model >= IX3M_EASY) {
 		commands = &ix3m;
 	}
 
@@ -372,7 +383,7 @@ divesystem_idive_device_foreach (dc_device_t *abstract, dc_dive_callback_t callb
 	// Emit a device info event.
 	dc_event_devinfo_t devinfo;
 	devinfo.model = array_uint16_le (packet);
-	devinfo.firmware = 0;
+	devinfo.firmware = array_uint32_le (packet + 2);
 	devinfo.serial = array_uint32_le (packet + 6);
 	device_event_emit (abstract, DC_EVENT_DEVINFO, &devinfo);
 
@@ -382,6 +393,14 @@ divesystem_idive_device_foreach (dc_device_t *abstract, dc_dive_callback_t callb
 	vendor.size = commands->id.size;
 	device_event_emit (abstract, DC_EVENT_VENDOR, &vendor);
 
+	if (device->model >= IX3M_EASY) {
+		// Detect the APOS4 firmware.
+		unsigned int apos4 = (devinfo.firmware / 10000000) >= 4;
+		if (apos4) {
+			commands = &ix3m_apos4;
+		}
+	}
+
 	unsigned char cmd_range[] = {commands->range.cmd, 0x8D};
 	rc = divesystem_idive_transfer (device, cmd_range, sizeof(cmd_range), packet, commands->range.size);
 	if (rc != DC_STATUS_SUCCESS)
@@ -429,20 +448,28 @@ divesystem_idive_device_foreach (dc_device_t *abstract, dc_dive_callback_t callb
 		dc_buffer_reserve(buffer, commands->header.size + commands->sample.size * nsamples);
 		dc_buffer_append(buffer, packet, commands->header.size);
 
-		for (unsigned int j = 0; j < nsamples; ++j) {
+		for (unsigned int j = 0; j < nsamples; j += commands->nsamples) {
 			unsigned int idx = j + 1;
 			unsigned char cmd_sample[] = {commands->sample.cmd,
 				(idx     ) & 0xFF,
 				(idx >> 8) & 0xFF};
-			rc = divesystem_idive_transfer (device, cmd_sample, sizeof(cmd_sample), packet, commands->sample.size);
+			rc = divesystem_idive_transfer (device, cmd_sample, sizeof(cmd_sample), packet, commands->sample.size * commands->nsamples);
 			if (rc != DC_STATUS_SUCCESS)
 				return rc;
 
+			// If the number of samples is not an exact multiple of the
+			// number of samples per packet, then the last packet
+			// appears to contain garbage data. Ignore those samples.
+			unsigned int n = commands->nsamples;
+			if (j + n > nsamples) {
+				n = nsamples - j;
+			}
+
 			// Update and emit a progress event.
-			progress.current = i * NSTEPS + STEP(j + 2, nsamples + 1);
+			progress.current = i * NSTEPS + STEP(j + n + 1, nsamples + 1);
 			device_event_emit (abstract, DC_EVENT_PROGRESS, &progress);
 
-			dc_buffer_append(buffer, packet, commands->sample.size);
+			dc_buffer_append(buffer, packet, commands->sample.size * n);
 		}
 
 		unsigned char *data = dc_buffer_get_data(buffer);
diff --git a/src/divesystem_idive_parser.c b/src/divesystem_idive_parser.c
index 968765c..473dc57 100644
--- a/src/divesystem_idive_parser.c
+++ b/src/divesystem_idive_parser.c
@@ -37,6 +37,7 @@
 #define SZ_SAMPLE_IDIVE 0x2A
 #define SZ_HEADER_IX3M  0x36
 #define SZ_SAMPLE_IX3M  0x36
+#define SZ_SAMPLE_IX3M_APOS4 0x40
 
 #define NGASMIXES 8
 
@@ -53,8 +54,8 @@ typedef struct divesystem_idive_parser_t divesystem_idive_parser_t;
 
 struct divesystem_idive_parser_t {
 	dc_parser_t base;
+	unsigned int model;
 	unsigned int headersize;
-	unsigned int samplesize;
 	// Cached fields.
 	unsigned int cached;
 	unsigned int divemode;
@@ -97,12 +98,11 @@ divesystem_idive_parser_create (dc_parser_t **out, dc_context_t *context, unsign
 	}
 
 	// Set the default values.
-	if (model >= IX3M_EASY && model <= IX3M_REB) {
+	parser->model = model;
+	if (model >= IX3M_EASY) {
 		parser->headersize = SZ_HEADER_IX3M;
-		parser->samplesize = SZ_SAMPLE_IX3M;
 	} else {
 		parser->headersize = SZ_HEADER_IDIVE;
-		parser->samplesize = SZ_SAMPLE_IDIVE;
 	}
 	parser->cached = 0;
 	parser->divemode = INVALID;
@@ -241,8 +241,27 @@ divesystem_idive_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callba
 	unsigned int mode_previous = INVALID;
 	unsigned int divemode = INVALID;
 
+	unsigned int nsamples = array_uint16_le (data + 1);
+	unsigned int samplesize = SZ_SAMPLE_IDIVE;
+	if (parser->model >= IX3M_EASY) {
+		// Detect the APOS4 firmware.
+		unsigned int firmware = array_uint32_le(data + 0x2A);
+		unsigned int apos4 = (firmware / 10000000) >= 4;
+		if (apos4) {
+			// Dive downloaded and recorded with the APOS4 firmware.
+			samplesize = SZ_SAMPLE_IX3M_APOS4;
+		} else if (size == parser->headersize + nsamples * SZ_SAMPLE_IX3M_APOS4) {
+			// Dive downloaded with the APOS4 firmware, but recorded
+			// with an older firmware.
+			samplesize = SZ_SAMPLE_IX3M_APOS4;
+		} else {
+			// Dive downloaded and recorded with an older firmware.
+			samplesize = SZ_SAMPLE_IX3M;
+		}
+	}
+
 	unsigned int offset = parser->headersize;
-	while (offset + parser->samplesize <= size) {
+	while (offset + samplesize <= size) {
 		dc_sample_value_t sample = {0};
 
 		// Time (seconds).
@@ -328,7 +347,7 @@ divesystem_idive_parser_samples_foreach (dc_parser_t *abstract, dc_sample_callba
 		sample.cns = cns / 100.0;
 		if (callback) callback (DC_SAMPLE_CNS, sample, userdata);
 
-		offset += parser->samplesize;
+		offset += samplesize;
 	}
 
 	// Cache the data for later use.
diff --git a/src/hw_ostc3.c b/src/hw_ostc3.c
index b8693cb..e7b7d9e 100644
--- a/src/hw_ostc3.c
+++ b/src/hw_ostc3.c
@@ -125,6 +125,8 @@ static const unsigned char ostc3_key[16] = {
 };
 
 static dc_status_t hw_ostc3_device_set_fingerprint (dc_device_t *abstract, const unsigned char data[], unsigned int size);
+static dc_status_t hw_ostc3_device_read (dc_device_t *abstract, unsigned int address, unsigned char data[], unsigned int size);
+static dc_status_t hw_ostc3_device_write (dc_device_t *abstract, unsigned int address, const unsigned char data[], unsigned int size);
 static dc_status_t hw_ostc3_device_dump (dc_device_t *abstract, dc_buffer_t *buffer);
 static dc_status_t hw_ostc3_device_foreach (dc_device_t *abstract, dc_dive_callback_t callback, void *userdata);
 static dc_status_t hw_ostc3_device_close (dc_device_t *abstract);
@@ -133,8 +135,8 @@ static const dc_device_vtable_t hw_ostc3_device_vtable = {
 	sizeof(hw_ostc3_device_t),
 	DC_FAMILY_HW_OSTC3,
 	hw_ostc3_device_set_fingerprint, /* set_fingerprint */
-	NULL, /* read */
-	NULL, /* write */
+	hw_ostc3_device_read, /* read */
+	hw_ostc3_device_write, /* write */
 	hw_ostc3_device_dump, /* dump */
 	hw_ostc3_device_foreach, /* foreach */
 	hw_ostc3_device_close /* close */
@@ -1181,7 +1183,7 @@ hw_ostc3_firmware_block_read (hw_ostc3_device_t *device, unsigned int addr, unsi
 }
 
 static dc_status_t
-hw_ostc3_firmware_block_write (hw_ostc3_device_t *device, unsigned int addr, unsigned char block[], unsigned int block_size)
+hw_ostc3_firmware_block_write (hw_ostc3_device_t *device, unsigned int addr, const unsigned char block[], unsigned int block_size)
 {
 	unsigned char buffer[3 + SZ_FIRMWARE_BLOCK];
 
@@ -1446,6 +1448,87 @@ hw_ostc3_device_fwupdate (dc_device_t *abstract, const char *filename)
 	}
 }
 
+static dc_status_t
+hw_ostc3_device_read (dc_device_t *abstract, unsigned int address, unsigned char data[], unsigned int size)
+{
+	dc_status_t status = DC_STATUS_SUCCESS;
+	hw_ostc3_device_t *device = (hw_ostc3_device_t *) abstract;
+
+	if ((address % SZ_FIRMWARE_BLOCK != 0) ||
+		(size % SZ_FIRMWARE_BLOCK != 0)) {
+		ERROR (abstract->context, "Address or size not aligned to the page size!");
+		return DC_STATUS_INVALIDARGS;
+	}
+
+	// Make sure the device is in service mode.
+	status = hw_ostc3_device_init (device, SERVICE);
+	if (status != DC_STATUS_SUCCESS) {
+		return status;
+	}
+
+	if (device->hardware == OSTC4) {
+		return DC_STATUS_UNSUPPORTED;
+	}
+
+	unsigned int nbytes = 0;
+	while (nbytes < size) {
+		// Read a memory page.
+		status = hw_ostc3_firmware_block_read (device, address + nbytes, data + nbytes, SZ_FIRMWARE_BLOCK);
+		if (status != DC_STATUS_SUCCESS) {
+			ERROR (abstract->context, "Failed to read block.");
+			return status;
+		}
+
+		nbytes += SZ_FIRMWARE_BLOCK;
+	}
+
+	return DC_STATUS_SUCCESS;
+}
+
+static dc_status_t
+hw_ostc3_device_write (dc_device_t *abstract, unsigned int address, const unsigned char data[], unsigned int size)
+{
+	dc_status_t status = DC_STATUS_SUCCESS;
+	hw_ostc3_device_t *device = (hw_ostc3_device_t *) abstract;
+
+	if ((address % SZ_FIRMWARE_BLOCK != 0) ||
+		(size % SZ_FIRMWARE_BLOCK != 0)) {
+		ERROR (abstract->context, "Address or size not aligned to the page size!");
+		return DC_STATUS_INVALIDARGS;
+	}
+
+	// Make sure the device is in service mode.
+	status = hw_ostc3_device_init (device, SERVICE);
+	if (status != DC_STATUS_SUCCESS) {
+		return status;
+	}
+
+	if (device->hardware == OSTC4) {
+		return DC_STATUS_UNSUPPORTED;
+	}
+
+	// Erase the memory pages.
+	status = hw_ostc3_firmware_erase (device, address, size);
+	if (status != DC_STATUS_SUCCESS) {
+		ERROR (abstract->context, "Failed to erase blocks.");
+		return status;
+	}
+
+	unsigned int nbytes = 0;
+	while (nbytes < size) {
+		// Write a memory page.
+		status = hw_ostc3_firmware_block_write (device, address + nbytes, data + nbytes, SZ_FIRMWARE_BLOCK);
+		if (status != DC_STATUS_SUCCESS) {
+			ERROR (abstract->context, "Failed to write block.");
+			return status;
+		}
+
+		nbytes += SZ_FIRMWARE_BLOCK;
+	}
+
+	return DC_STATUS_SUCCESS;
+}
+
 static dc_status_t
 hw_ostc3_device_dump (dc_device_t *abstract, dc_buffer_t *buffer)
 {
diff --git a/src/mares_iconhd.c b/src/mares_iconhd.c
index 9a2179c..3a73968 100644
--- a/src/mares_iconhd.c
+++ b/src/mares_iconhd.c
@@ -42,6 +42,7 @@
 #define PUCKPRO   0x18
 #define NEMOWIDE2 0x19
 #define PUCK2     0x1F
+#define QUAD      0x29
 
 #define ACK 0xAA
 #define EOF 0xEA
@@ -125,6 +126,7 @@ mares_iconhd_get_model (mares_iconhd_device_t *device)
 		{"Puck Pro",    PUCKPRO},
 		{"Nemo Wide 2", NEMOWIDE2},
 		{"Puck 2",      PUCK2},
+		{"Quad",        QUAD},
 	};
 
 	// Check the product name in the version packet against the list
@@ -292,6 +294,7 @@ mares_iconhd_device_open (dc_device_t **out, dc_context_t *context, const char *
 	case NEMOWIDE2:
 	case SMART:
 	case SMARTAPNEA:
+	case QUAD:
 		device->layout = &mares_nemowide2_layout;
 		device->packetsize = 256;
 		break;
diff --git a/src/oceanic_atom2.c b/src/oceanic_atom2.c
index cccfc4e..da19e7f 100644
--- a/src/oceanic_atom2.c
+++ b/src/oceanic_atom2.c
@@ -101,7 +101,6 @@ static const oceanic_common_version_t oceanic_atom2_version[] = {
 
 static const oceanic_common_version_t oceanic_atom2a_version[] = {
 	{"MANTA  R\0\0  512K"},
-	{"WISDOM R\0\0  512K"},
 	{"INSIGHT2 \0\0 512K"},
 	{"OCEVEO30 \0\0 512K"},
 	{"ATMOSAI R\0\0 512K"},
@@ -132,6 +131,10 @@ static const oceanic_common_version_t oceanic_default_version[] = {
 	{"COMPMASK \0\0 512K"},
 };
 
+static const oceanic_common_version_t sherwood_wisdom_version[] = {
+	{"WISDOM R\0\0  512K"},
+};
+
 static const oceanic_common_version_t oceanic_proplus3_version[] = {
 	{"PROPLUS3 \0\0 512K"},
 };
@@ -288,6 +291,20 @@ static const oceanic_common_layout_t oceanic_atom2c_layout = {
 	0, /* pt_mode_serial */
 };
 
+static const oceanic_common_layout_t sherwood_wisdom_layout = {
+	0xFFF0, /* memsize */
+	0x0000, /* cf_devinfo */
+	0x0040, /* cf_pointers */
+	0x03D0, /* rb_logbook_begin */
+	0x0A40, /* rb_logbook_end */
+	8, /* rb_logbook_entry_size */
+	0x0A40, /* rb_profile_begin */
+	0xFE00, /* rb_profile_end */
+	0, /* pt_mode_global */
+	0, /* pt_mode_logbook */
+	0, /* pt_mode_serial */
+};
+
 static const oceanic_common_layout_t oceanic_proplus3_layout = {
 	0x10000, /* memsize */
 	0x0000, /* cf_devinfo */
@@ -645,6 +662,8 @@ oceanic_atom2_device_open (dc_device_t **out, dc_context_t *context, const char
 		device->base.layout = &oceanic_atom2b_layout;
 	} else if (OCEANIC_COMMON_MATCH (device->base.version, oceanic_atom2c_version)) {
 		device->base.layout = &oceanic_atom2c_layout;
+	} else if (OCEANIC_COMMON_MATCH (device->base.version, sherwood_wisdom_version)) {
+		device->base.layout = &sherwood_wisdom_layout;
 	} else if (OCEANIC_COMMON_MATCH (device->base.version, oceanic_proplus3_version)) {
 		device->base.layout = &oceanic_proplus3_layout;
 	} else if (OCEANIC_COMMON_MATCH (device->base.version, tusa_zenair_version)) {
diff --git a/src/parser.c b/src/parser.c
index 57ed568..ebbc6a6 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -149,10 +149,10 @@ dc_parser_new_internal (dc_parser_t **out, dc_context_t *context, dc_family_t fa
 		rc = atomics_cobalt_parser_create (&parser, context);
 		break;
 	case DC_FAMILY_SHEARWATER_PREDATOR:
-		rc = shearwater_predator_parser_create (&parser, context, serial);
+		rc = shearwater_predator_parser_create (&parser, context, model, serial);
 		break;
 	case DC_FAMILY_SHEARWATER_PETREL:
-		rc = shearwater_petrel_parser_create (&parser, context, serial);
+		rc = shearwater_petrel_parser_create (&parser, context, model, serial);
 		break;
 	case DC_FAMILY_DIVERITE_NITEKQ:
 		rc = diverite_nitekq_parser_create (&parser, context);
diff --git a/src/shearwater_petrel.h b/src/shearwater_petrel.h
index 4d70755..b51361f 100644
--- a/src/shearwater_petrel.h
+++ b/src/shearwater_petrel.h
@@ -34,7 +34,7 @@ dc_status_t
 shearwater_petrel_device_open (dc_device_t **device, dc_context_t *context, const char *name);
 
 dc_status_t
-shearwater_petrel_parser_create (dc_parser_t **parser, dc_context_t *context, unsigned int serial);
+shearwater_petrel_parser_create (dc_parser_t **parser, dc_context_t *context, unsigned int model, unsigned int serial);
 
 #ifdef __cplusplus
 }
diff --git a/src/shearwater_predator.h b/src/shearwater_predator.h
index 5485477..2b16e92 100644
--- a/src/shearwater_predator.h
+++ b/src/shearwater_predator.h
@@ -34,7 +34,7 @@ dc_status_t
 shearwater_predator_device_open (dc_device_t **device, dc_context_t *context, const char *name);
 
 dc_status_t
-shearwater_predator_parser_create (dc_parser_t **parser, dc_context_t *context, unsigned int serial);
+shearwater_predator_parser_create (dc_parser_t **parser, dc_context_t *context, unsigned int model, unsigned int serial);
 
 #ifdef __cplusplus
 }
diff --git a/src/shearwater_predator_parser.c b/src/shearwater_predator_parser.c
index 1e42d87..ae7f898 100644
--- a/src/shearwater_predator_parser.c
+++ b/src/shearwater_predator_parser.c
@@ -54,10 +54,14 @@
 
 #define NGASMIXES 10
 
+#define PREDATOR 2
+#define PETREL   3
+
 typedef struct shearwater_predator_parser_t shearwater_predator_parser_t;
 
 struct shearwater_predator_parser_t {
 	dc_parser_t base;
+	unsigned int model;
 	unsigned int petrel;
 	unsigned int samplesize;
 	// Cached fields.
@@ -67,6 +71,7 @@ struct shearwater_predator_parser_t {
 	unsigned int ngasmixes;
 	unsigned int oxygen[NGASMIXES];
 	unsigned int helium[NGASMIXES];
+	double calibration[3];
 	unsigned int serial;
 	dc_divemode_t mode;
 };
@@ -112,7 +117,7 @@ shearwater_predator_find_gasmix (shearwater_predator_parser_t *parser, unsigned
 
 
 static dc_status_t
-shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int serial, unsigned int petrel)
+shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int model, unsigned int serial, unsigned int petrel)
 {
 	shearwater_predator_parser_t *parser = NULL;
 	const dc_parser_vtable_t *vtable = NULL;
@@ -136,14 +141,11 @@ shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsig
 		return DC_STATUS_NOMEMORY;
 	}
 
-	// Initialize the base class.
+	// Set the default values.
+	parser->model = model;
 	parser->petrel = petrel;
+	parser->samplesize = samplesize;
 	parser->serial = serial;
-	if (petrel) {
-		parser->samplesize = SZ_SAMPLE_PETREL;
-	} else {
-		parser->samplesize = SZ_SAMPLE_PREDATOR;
-	}
 
 	// Set the default values.
 	parser->cached = 0;
@@ -163,16 +165,16 @@ shearwater_common_parser_create (dc_parser_t **out, dc_context_t *context, unsig
 
 
 dc_status_t
-shearwater_predator_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int serial)
+shearwater_predator_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int model, unsigned int serial)
 {
-	return shearwater_common_parser_create (out, context, serial, 0);
+	return shearwater_common_parser_create (out, context, model, serial, 0);
 }
 
 
 dc_status_t
-shearwater_petrel_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int serial)
+shearwater_petrel_parser_create (dc_parser_t **out, dc_context_t *context, unsigned int model, unsigned int serial)
 {
-	return shearwater_common_parser_create (out, context, serial, 1);
+	return shearwater_common_parser_create (out, context, model, serial, 1);
 }
 
 
@@ -297,6 +299,20 @@ shearwater_predator_parser_cache (shearwater_predator_parser_t *parser)
 		offset += parser->samplesize;
 	}
 
+	// Cache sensor calibration for later use
+	parser->calibration[0] = array_uint16_be(data + 87) / 100000.0;
+	parser->calibration[1] = array_uint16_be(data + 89) / 100000.0;
+	parser->calibration[2] = array_uint16_be(data + 91) / 100000.0;
+	// The Predator expects the mV output of the cells to be within 30mV
+	// to 70mV in 100% O2 at 1 atmosphere.
+	// If the calibration value is scaled with a factor 2.2, then the
+	// sensors lines up and matches the average.
+	if (parser->model == PREDATOR) {
+		for (size_t i = 0; i < 3; ++i) {
+			parser->calibration[i] *= 2.2;
+		}
+	}
+
 	// Cache the data for later use.
 	parser->headersize = headersize;
 	parser->footersize = footersize;
@@ -492,9 +508,22 @@ shearwater_predator_parser_samples_foreach (dc_parser_t *abstract, dc_sample_cal
 		unsigned int status = data[offset + 11];
 
 		if ((status & OC) == 0) {
-			// PPO2 -- only return PPO2 if we are in closed circuit mode
+			// PPO2
+#ifdef SENSOR_AVERAGE
 			sample.ppo2 = data[offset + 6] / 100.0;
 			if (callback) callback (DC_SAMPLE_PPO2, sample, userdata);
+#else
+			if ((status & PPO2_EXTERNAL) == 0) {
+				sample.ppo2 = data[offset + 12] * parser->calibration[0];
+				if (callback && (data[86] & 0x01)) callback (DC_SAMPLE_PPO2, sample, userdata);
+
+				sample.ppo2 = data[offset + 14] * parser->calibration[1];
+				if (callback && (data[86] & 0x02)) callback (DC_SAMPLE_PPO2, sample, userdata);
+
+				sample.ppo2 = data[offset + 15] * parser->calibration[2];
+				if (callback && (data[86] & 0x04)) callback (DC_SAMPLE_PPO2, sample, userdata);
+			}
+#endif
 
 			// Setpoint
 			if (parser->petrel) {
diff --git a/src/uwatec_meridian.c b/src/uwatec_meridian.c
index 077ec31..d59b855 100644
--- a/src/uwatec_meridian.c
+++ b/src/uwatec_meridian.c
@@ -228,7 +228,11 @@ uwatec_meridian_device_open (dc_device_t **out, dc_context_t *context, const cha
 	dc_serial_purge (device->port, DC_DIRECTION_ALL);
 
 	// Perform the handshaking.
-	uwatec_meridian_handshake (device);
+	status = uwatec_meridian_handshake (device);
+	if (status != DC_STATUS_SUCCESS) {
+		ERROR (context, "Failed to handshake with the device.");
+		goto error_close;
+	}
 
 	*out = (dc_device_t*) device;
 
diff --git a/src/uwatec_smart.c b/src/uwatec_smart.c
index 2b94a3b..425e76e 100644
--- a/src/uwatec_smart.c
+++ b/src/uwatec_smart.c
@@ -191,7 +191,11 @@ uwatec_smart_device_open (dc_device_t **out, dc_context_t *context)
 	}
 
 	// Perform the handshaking.
-	uwatec_smart_handshake (device);
+	status = uwatec_smart_handshake (device);
+	if (status != DC_STATUS_SUCCESS) {
+		ERROR (context, "Failed to handshake with the device.");
+		goto error_close;
+	}
 
 	*out = (dc_device_t*) device;