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Protocol

Water Linked DVL protocol

Describes the Water Linked DVL protocols (serial and ethernet).

Terminology

  • DVL - Doppler Velocity Log - Uses hydro-acoustic beams to measure the velocity at which the DVL is moving across a surface (typically an unmoving one such as the sea bottom), and the distance to this surface.
  • ACK - Acknowledgement. The command issued was successful.
  • NAK - Negative acknowledgement. The command issued failed.
  • Ping - A pulse of sound sent by the DVL
  • Time of validity - Timestamp of the surface reflection ('center of ping')
  • Time of transmission - Timestamp taken directly before sending data over the serial or TCP protocols. The difference between time of transmission and time of validity includes both the time for the acoustic wave to travel from the surface from which it was reflected back to the DVL, and the decoding and processing of this signal internally in the DVL.

Version

This document describes serial protocol version 2.4.x (major.minor.patch) and JSON protocol json_v3:

  • MAJOR version increments represent incompatible API changes
  • MINOR version increments represent additional backwards-compatible functionality
  • PATCH version increments represent backwards-compatible bug fixes

Version history overview

Software release Serial protocol version Ethernet protocol version Main protocol improvements
2.2.1 2.4.0 json_v3 Add serial output protocol configuration, range mode configuration and calibrate gyro command, Fix missing line ending in configuration (JSON), fix dark mode enabled naming inconsistency (JSON), change speed of sound and mounting rotation offset from integer to float
2.1.0 2.3.0 json_v3 Add configuration, add time_of_validity/time_of_transmission, add covariance (JSON)
2.0.8 2.2.0 json_v2 Add position estimation, add IMU output
1.6.0 2.1.0 - Initial (velocity only)

JSON protocol (TCP)

Overview

The DVL supports sending velocity, transducer, and position updates using the Transmission Control Protocol (TCP). The DVL runs a TCP server on port 16171.

The format of each packet is JSON.

Velocity-and-transducer report

A velocity-and-transducer report is sent for each velocity calculation of the DVL. The rate depends on the altitude of the DVL (vertical distance to the sea bottom or other reflecting surface), but will be in the range 2-15 Hz.

The X, Y, and Z axes are with respect to body frame of the DVL, or the vehicle frame if the DVL is mounted on a vehicle at an angle, specified as a 'mounting rotation offset', from the forward axis of the vehicle.

The messages are delimited by newline.

Variable Description
time Milliseconds since last velocity report (ms)
vx Velocity in x direction (m/s)
vy Velocity in y direction (m/s)
vz Velocity in z direction (m/s)
fom Figure of merit, a measure of the accuracy of the velocities (m/s)
covariance Covariance matrix for the velocities. The figure of merit is calculated from this (entries in (m/s)^2)
altitude Vertical distance to the reflecting surface (m)
transducers Is a list containing information from each transducer: [id, velocity (m/s), distance (m), rssi (dBm), nsd (dBm), beam_valid (True/False)]
velocity_valid If true, the DVL has a lock on the reflecting surface, and the altitude and velocities are valid (True/False)
status Reports if there are any issues with the DVL (0 for normal operation, 1 if operational issues such as high temperature)
time_of_validity Timestamp of the surface reflection, aka 'center of ping' (Unix timestamp in microseconds)
time_of_transmission Timestamp from immediately before sending of the report over TCP (Unix timestamp in microseconds)
format Format type and version for this report: json_v3
type Report type: velocity

Example of TCP report (indented for legibility)

{
  "time": 106.3935775756836,
  "vx": -3.713480691658333e-05,
  "vy": 5.703703573090024e-05,
  "vz": 2.4990416932269e-05,
  "fom": 0.00016016385052353144,
  "covariance": [
    [
      2.4471841442164077e-08,
      -3.3937477272871774e-09,
      -1.6659699175747278e-09
    ],
    [
      -3.3937477272871774e-09,
      1.4654466085062268e-08,
      4.0409570134514183e-10
    ],
    [
      -1.6659699175747278e-09,
      4.0409570134514183e-10,
      1.5971971523143225e-09
    ]
  ],
  "altitude": 0.4949815273284912,
  "transducers": [
    {
      "id": 0,
      "velocity": 0.00010825289791682735,
      "distance": 0.5568000078201294,
      "rssi": -30.494251251220703,
      "nsd": -88.73271179199219,
      "beam_valid": true
    },
    {
      "id": 1,
      "velocity": -1.4719001228513662e-05,
      "distance": 0.5663999915122986,
      "rssi": -31.095735549926758,
      "nsd": -89.5116958618164,
      "beam_valid": true
    },
    {
      "id": 2,
      "velocity": 2.7863150535267778e-05,
      "distance": 0.537600040435791,
      "rssi": -27.180519104003906,
      "nsd": -96.98075103759766,
      "beam_valid": true
    },
    {
      "id": 3,
      "velocity": 1.9419496311456896e-05,
      "distance": 0.5472000241279602,
      "rssi": -28.006759643554688,
      "nsd": -88.32147216796875,
      "beam_valid": true
    }
  ],
  "velocity_valid": true,
  "status": 0,
  "format": "json_v3",
  "type": "velocity",
  "time_of_validity": 1638191471563017,
  "time_of_transmission": 1638191471752336
}

Dead reckoning report

A dead reckoning report outputs the current speed, position, and orientation of the DVL as calculated by dead reckoning, with respect to a frame defined by the axes of the DVL's body frame, or vehicle frame if a mounting rotation offset is set, at the start of the dead reckoning run. The expected update rate is 5 Hz.

Variable Description
ts Time stamp of report (Unix timestamp in seconds)
x Distance in X direction (m)
y Distance in Y direction (m)
z Distance in downward direction (m)
std Standard deviation (figure of merit) for position (m)
roll Rotation around X axis (degrees)
pitch Rotation around Y axis (degrees)
yaw Rotation around Z axis, i.e. heading (degrees)
type Report type: position_local
status Reports if there are any issues with the DVL (0 if no errors, 1 otherwise)
format Format type and version for this report: json_v3

Example of a dead reckoning report.

{
  "ts": 49056.809,
  "x": 12.43563613697886467,
  "y": 64.617631152402609587,
  "z": 1.767641898933798075,
  "std": 0.001959984190762043,
  "roll": 0.6173566579818726,
  "pitch": 0.6173566579818726,
  "yaw": 0.6173566579818726,
  "type": "position_local",
  "status": 0,
  "format": "json_v3"
}

Reset dead reckoning

Dead reckoning can be reset by issuing the reset_dead_reckoning command:

{"command": "reset_dead_reckoning"}

The response will be as follows if the reset is successful. If unsuccessful, success will be false, and a non-empty error_message will be provided.

{
  "response_to":"reset_dead_reckoning",
  "success": true,
  "error_message": "",
  "result": null,
  "format": "json_v3",
  "type": "response"
}

Calibrate gyro

The gyro can be calibrated by issuing the calibrate_gyro command:

{"command":"calibrate_gyro"}

The response will be as follows if the calibration is successful. If unsuccessful, success will be false, and a non-empty error_message will be provided.

{
  "response_to": "calibrate_gyro",
  "success": true,
  "error_message": "",
  "result": null,
  "format": "json_v3",
  "type": "response"
}

Configuration over JSON

Configuration parameters

Variable Description
speed_of_sound Speed of sound (1000-2000 m/s). Integer
mounting_rotation_offset See the definition of the vehicle frame of the DVL. Typically 0, but can be set to be non-zero if the forward axis of the DVL is not aligned with the forward axis of a vehicle on which it is mounted (0-360 degrees). Integer
acoustic_enabled true for normal operation of the DVL,false when the sending of acoustic waves from the DVL is disabled (e.g. to save power or slow down its heating up in air)
dark_mode_enabled true when the LED operates as normal, false for no blinking of the LED (e.g. if the LED is interfering with a camera)
range_mode auto when operating as normal, otherwise see range mode configuration

Fetching current configuration

The current configuration of the DVL can be obtained by issuing the get_config command:

{"command": "get_config"}

If the configuration is successfully fetched, the response will be in the following format. If not, success will be false, a non-empty error_message string will be provided, and result will be null.

{
  "response_to":"get_config",
  "success":true,
  "error_message":"",
  "result":{
    "speed_of_sound":1475.00,
    "acoustic_enabled":true,
    "dark_mode_enabled":false,
    "mounting_rotation_offset":20.00,
    "range_mode":"auto"
  },
  "format":"json_v3",
  "type":"response"
}

Setting configuration parameters

Setting of configuration parameters can be carried out by issuing a set_config in the following format, including those parameters which are to be set:

{"command":"set_config","parameters":{"speed_of_sound":1480}}

If the parameters are successfully set, the response will be in the following format. If not, success will be false, and a non-empty error_message string will be provided.

{
  "response_to": "set_config",
  "success": true,
  "error_message": "",
  "result" :null,
  "format": "json_v3",
  "type": "response"
}

Serial Protocol

Overview

The serial communication format is 115200 8-N-1 (no hardware flow control).

Packets sent to and received from the DVL start with a w and end with LF, CR+LF, or CR. The packet format is:

Start byte Direction Command Options (0 to many) Checksum End byte
w c or r x ,[option] *xx \n, \r\n, or \r

Direction is c (short for 'command') for packets sent to the DVL, and r (short for 'response') for packets sent from the DVL. The commands can be sent as a string or entered one character at a time from a terminal.

Note

The checksum is optional when sending commands to the DVL. The DVL always returns a checksum. The checksum algorithm is CRC-8 and it is formatted as a hexadecimal number using 2 lower-case characters (ex: *c3). See below for details.

Command overview

The commands in the table are shown without the checksum and without the mandatory line ending (any of \n, \r\n, or \r) for readability. In all cases, the response to a submitted command may be wrn, wr?, or wr! (see below for details), but only the format of a successful response is listed.

Command Description Response Description
wcv Get protocol version wrv,[major],[minor],[patch] Protocol version. eg: wrv,2.4.0
wcw Get product detail wrw,[name],[version],[chipID],[IP address] Where type is dvl, name is product name, version is software version, chip ID is the chip ID and optionally the IP address if connected to DHCP server: eg: wrw,dvl-a50,2.2.1,0xfedcba98765432 or wrw,dvl-a50,2.2.1,0xfedcba98765432,10.11.12.140
wcs,[speed_of_sound],[mounting_rotation_offset],[acoustic_enabled],[dark_mode_enabled] Set configuration parameters wra Successfully set the specified configuration parameters. See Configuration for details
wcc Get current configuration wrc,[speed_of_sound],[mounting_rotation_offset],[acoustic_enabled],[dark_mode_enabled] Entire current configuration. See Configuration for details
wcr Reset dead reckoning wra Successfully started a new dead reckoning run
wcg Calibrate gyro wra Successfully calibrated gyro
wcp Change serial output protocol wra Successfully changed output protocol
wrz,[details below] Velocities calculated
wru,[details below] Transducer information
wrp,[details below] Dead reckoning report
wrx,[details below] DEPRECATED: Velocities calculated (old format)
wrt,[details below] DEPRECATED: Transducer information (old format)
wr? Malformed request: packet cannot be understood
wr! Malformed request: packet does not match the given checksum
wrn Not acknowledged (nack): an error occurred when handling the packet

Velocity report (wrz)

A velocity report is outputted for each velocity calculation of the DVL. The rate depends on the altitude of the DVL (vertical distance to the sea bottom or other reflecting surface), but will be in the range 2-15 Hz.

The X, Y, and Z axes are with respect to body frame of the DVL, or the vehicle frame if the DVL is mounted on a vehicle at an angle, specified as a 'mounting rotation offset', from the forward axis of the vehicle.

The report has the following format: wrz,[vx],[vy],[vz],[valid],[altitude],[fom],[covariance],[time_of_validity],[time_of_transmission],[time],[status]

Variable Description
vx Velocity in x direction (m/s)
vy Velocity in y direction (m/s)
vz Velocity in z direction (m/s)
valid If y, the DVL has a lock on the reflecting surface, and the altitude and velocities are valid (y/n)
altitude Measured altitude to the bottom (m)
fom Figure of merit, a measure of the accuracy of the velocities (m/s)
covariance Covariance matrix for the velocities. The figure of merit is calculated from this. 9 entries ((m/s)^2) separated by ;
time_of_validity Timestamp of the surface reflection, aka 'center of ping' (Unix timestamp in microseconds)
time_of_transmission Timestamp from immediately before sending of the report over TCP (Unix timestamp in microseconds)
time Milliseconds since last velocity report (ms)
status 0 for normal operation, 1 for operational issues such as high temperature

Example where all velocities are valid:

wrz,0.120,-0.400,2.000,y,1.30,1.855,1e-07;0;1.4;0;1.2;0;0.2;0;1e+09,7,14,123.00,1*50

Transducer report (wru)

A transducer report is outputted for each of the four transducers of the DVL for each velocity calculation of the DVL. The rate will be the same as that of the velocity report. If the transducer did not receive a signal which could be successfully decoded, distance will be set to -1, and velocity will be set to 0. RSSI and NSD will be outputted in all cases.

The report has the following format: wru,[id],[velocity],[distance],[rssi],[nsd]

Variable Description
id Transducer number
velocity Velocity in the direction of the transducer (m/s)
distance Distance (parallel to the transducer beam, i.e. not the vertical distance) to the reflecting surface from this transducer (m)
rssi Received signal strength indicator: strength of the signal received by this transducer (dBm)
nsd Noise spectral density: strength of the background noise received by this transducer (dBm)

Example where all data is valid:

wru,0,0.070,1.10,-40,-95*9c
wru,1,-0.500,1.25,-62,-104*f0
wru,2,2.200,1.40,-56,-98*18
wru,3,1.800,1.35,-58,-96*a3

Dead reckoning report (wrp)

A dead reckoning report outputs the current speed, position, and orientation of the DVL as calculated by dead reckoning, with respect to a frame defined by the axes of the DVL's body frame, or vehicle frame if a mounting rotation offset is set, at the start of the dead reckoning run. The expected update rate is 5 Hz.

The format is: wrp,[time_stamp],[x],[y],[z],[pos_std],[roll],[pitch],[yaw],[status]

Variable Description
time_stamp Time stamp of report (Unix timestamp in seconds)
x Distance in X direction (m)
y Distance in Y direction (m)
z Distance in downward direction (m)
pos_std Standard deviation (Figure of merit) for position (m)
roll Rotation around X axis (degrees)
pitch Rotation around Y axis (degrees)
yaw Rotation around Z axis, i.e. heading (degrees)
status Reports if there are any issues with the DVL (0 if no errors, 1 otherwise)

Example:

wrp,49056.809,0.41,0.15,1.23,0.4,53.9,13.0,19.3,0*de
wrp,49057.269,0.39,0.18,1.23,0.4,53.9,13.0,19.3,0*e2

Reset dead reckoning (wcr)

Dead reckoning can be reset by issuing the wcr command. The reply will be an ack (wra) if the reset is successful, and a nak (wrn) if not.

Calibrate gyro (wcg)

The gyro can be calibrated by issuing the wcg command. The reply will be an ack (wra) if the reset is successful, and a nak (wrn) if not.

Change serial output protocol (wcp)

The serial output protocol in use can configured by issuing the wcp command. The selected protocol is persistent over reboots.

wcp,[protocol number]

The supported protocols are:

Protocol number Name Description
0 Output disabled No output on serial. Recommended if serial port is not used to lower latency on ethernet protocols.
1 Backward compatible All output including the deprecated wrx and wrt sentences.
2 PD6 PD6 protocol output. See PD6 protocol description
3 Latest All output excluding the deprecated wrx and wrt sentences.

The reply will be an ack (wra) if the protocol change is successful, and a nak (wrn) if not.

Example setting configuring output to use protocol number 3:

wcp,3

Configuration over serial

Configuration parameters

Variable Description
speed_of_sound Speed of sound (1000-2000 m/s). Float
mounting_rotation_offset See the definition of the vehicle frame of the DVL. Typically 0, but can be set to be non-zero if the forward axis of the DVL is not aligned with the forward axis of a vehicle on which it is mounted (0-360 degrees). Float
acoustic_enabled y for normal operation of the DVL,n when the sending of acoustic waves from the DVL is disabled (e.g. to save power or slow down its heating up in air)
dark_mode_enabled n when the LED operates as normal. y for no blinking of LED (e.g. if the LED is interfering with a camera)
range_mode auto when operating as normal, otherwise see range mode configuration

Note

For backward compatibility the range_mode parameter is optional when setting the configuration. It will always be returned when reading the configuration (wcc). Speed of sound and mounting rotation was changed from integer to float in serial protocol 2.4.0

Fetching current configuration

The current configuration of the DVL can be obtained by issuing the wcc command.

If the configuration is successfully fetched, the response will be in the following format. If not, a nak wrn will be returned.

wrc,[speed_of_sound],[mounting_rotation_offset],[acoustic_enabled],[dark_mode_enabled],[range_mode]

Setting configuration parameters

Setting of configuration parameters can be carried out by issuing the wcs command in the following format.

wcs,[speed_of_sound],[mounting_rotation_offset],[acoustic_enabled],[dark_mode_enabled],[range_mode]

Those parameters which are not to be set can be left blank.

Example for setting dark mode without changing the other parameters:

wcs,,,,y,

Example for setting speed of sound to 1450 m/s and disabling acoustics, without changing the other parameters:

wcs,1450,,n,,

The response will be an ack wra if the parameters are successfully set, a nak wrn if the command was successfully parsed but the parameters were not successfully set, and a malformed request wr? if the command was not successfully parsed, e.g. if the wrong number of parameters was used, or either speed_of_sound or mounting_rotation_offset was not an integer.

The new configuration will not be returned in the response, but can be obtained by issuing a wcc command as above.

Velocity report, old format (wrx) [Deprecated]

Same purpose as the velocity report, but in an older format:

wrx,[time],[vx],[vy],[vz],[fom],[altitude],[valid],[status]

Variable Description
time Milliseconds since last velocity report (ms)
vx Velocity in x direction (m/s)
vy Velocity in y direction (m/s)
vz Velocity in z direction (m/s)
fom Figure of merit, a measure of the accuracy of the velocities (m/s)
altitude Vertical distance to the reflecting surface (m)
valid If y, the DVL has lock on the reflecting surface, and the altitude and velocities are valid (y/n)
status 0 for normal operation, 1 for operational issues such as high temperature

Example where velocities are valid:

wrx,112.83,0.007,0.017,0.006,0.000,0.93,y,0*d2
wrx,140.43,0.008,0.021,0.012,0.000,0.92,y,0*b7
wrx,118.47,0.009,0.020,0.013,0.000,0.92,y,0*54

Example where velocities and altitude are not valid and a high temperature warning occurs:

wrx,1075.51,0.000,0.000,0.000,2.707,-1.00,n,1*04
wrx,1249.29,0.000,0.000,0.000,2.707,-1.00,n,1*6a
wrx,1164.94,0.000,0.000,0.000,2.707,-1.00,n,1*39

Transducer report, old format (wrt) [Deprecated]

Same purpose as the transducer report, but in an older format, and combining the data of all four transducers:

wrt,[dist_1],[dist_2],[dist_3],[dist_4]

Variable Description
dist_1 Distance (parallel to the transducer beam, i.e. not the vertical distance) to reflecting surface from transducer 1 (m)
dist_2 Distance to reflecting surface from transducer 2 (m)
dist_3 Distance to reflecting surface from transducer 3 (m)
dist_4 Distance to reflecting surface from transducer 4 (m)

Example where all distances are valid:

wrt,15.00,15.20,14.90,14.20*b1
wrt,14.90,15.10,14.80,14.10*ac

Example where distance is not valid for transducer 4:

wrt,14.90,15.10,14.80,-1.00*53
wrt,15.00,15.20,14.90,-1.00*71

Checksum

The checksum algorithm is CRC-8 (Polynomal: 0x07, Init: 0x00, RefIn/RefOut: false, XorOut: 0x00, Check: 0xf4). Checksum is formatted as a hexadecimal number using 2 lower-case characters (ex: *c3).

Compatible implementations:

Example for how to verify checksum using Python 3 and crcmod:

crc = crcmod.predefined.mkPredefinedCrcFun("crc-8")
sentence = b"wrx,1164.94,0.000,0.000,0.000,2.707,-1.00,n,1*39"
data, checksum = sentence.split(b"*")

if crc(data) == int(checksum, 16):
    print("CRC valid")
else:
    print("CRC invalid")

The crcmod python package can generate code in other languages. Here is an example (subject to the MIT License) for C which should be straightforward to adapt to other languages.

static const uint8_t lookup_table[256] = {
    0x00U,0x07U,0x0EU,0x09U,0x1CU,0x1BU,0x12U,0x15U,
    0x38U,0x3FU,0x36U,0x31U,0x24U,0x23U,0x2AU,0x2DU,
    0x70U,0x77U,0x7EU,0x79U,0x6CU,0x6BU,0x62U,0x65U,
    0x48U,0x4FU,0x46U,0x41U,0x54U,0x53U,0x5AU,0x5DU,
    0xE0U,0xE7U,0xEEU,0xE9U,0xFCU,0xFBU,0xF2U,0xF5U,
    0xD8U,0xDFU,0xD6U,0xD1U,0xC4U,0xC3U,0xCAU,0xCDU,
    0x90U,0x97U,0x9EU,0x99U,0x8CU,0x8BU,0x82U,0x85U,
    0xA8U,0xAFU,0xA6U,0xA1U,0xB4U,0xB3U,0xBAU,0xBDU,
    0xC7U,0xC0U,0xC9U,0xCEU,0xDBU,0xDCU,0xD5U,0xD2U,
    0xFFU,0xF8U,0xF1U,0xF6U,0xE3U,0xE4U,0xEDU,0xEAU,
    0xB7U,0xB0U,0xB9U,0xBEU,0xABU,0xACU,0xA5U,0xA2U,
    0x8FU,0x88U,0x81U,0x86U,0x93U,0x94U,0x9DU,0x9AU,
    0x27U,0x20U,0x29U,0x2EU,0x3BU,0x3CU,0x35U,0x32U,
    0x1FU,0x18U,0x11U,0x16U,0x03U,0x04U,0x0DU,0x0AU,
    0x57U,0x50U,0x59U,0x5EU,0x4BU,0x4CU,0x45U,0x42U,
    0x6FU,0x68U,0x61U,0x66U,0x73U,0x74U,0x7DU,0x7AU,
    0x89U,0x8EU,0x87U,0x80U,0x95U,0x92U,0x9BU,0x9CU,
    0xB1U,0xB6U,0xBFU,0xB8U,0xADU,0xAAU,0xA3U,0xA4U,
    0xF9U,0xFEU,0xF7U,0xF0U,0xE5U,0xE2U,0xEBU,0xECU,
    0xC1U,0xC6U,0xCFU,0xC8U,0xDDU,0xDAU,0xD3U,0xD4U,
    0x69U,0x6EU,0x67U,0x60U,0x75U,0x72U,0x7BU,0x7CU,
    0x51U,0x56U,0x5FU,0x58U,0x4DU,0x4AU,0x43U,0x44U,
    0x19U,0x1EU,0x17U,0x10U,0x05U,0x02U,0x0BU,0x0CU,
    0x21U,0x26U,0x2FU,0x28U,0x3DU,0x3AU,0x33U,0x34U,
    0x4EU,0x49U,0x40U,0x47U,0x52U,0x55U,0x5CU,0x5BU,
    0x76U,0x71U,0x78U,0x7FU,0x6AU,0x6DU,0x64U,0x63U,
    0x3EU,0x39U,0x30U,0x37U,0x22U,0x25U,0x2CU,0x2BU,
    0x06U,0x01U,0x08U,0x0FU,0x1AU,0x1DU,0x14U,0x13U,
    0xAEU,0xA9U,0xA0U,0xA7U,0xB2U,0xB5U,0xBCU,0xBBU,
    0x96U,0x91U,0x98U,0x9FU,0x8AU,0x8DU,0x84U,0x83U,
    0xDEU,0xD9U,0xD0U,0xD7U,0xC2U,0xC5U,0xCCU,0xCBU,
    0xE6U,0xE1U,0xE8U,0xEFU,0xFAU,0xFDU,0xF4U,0xF3U,
};

uint8_t crc8(uint8_t *message, int message_length) {
    uint8_t checksum = 0;
    while (message_length > 0) {
        checksum = lookup_table[*message ^ checksum];
        message++;
        message_length--;
    }
    return checksum;
}

PD6 protocol (TCP/Serial)

Overview

The PD6 support allows for integration with equipment that may already have a PD6 protocol interface, removing the necessity to create a driver based on the standard Water Linked protocol. PD6 protocol is supported for output via serial and ethernet. PD6 protocol over TCP is always enabled. The port in use is configurable in the GUI. The default port is TCP 1037. The serial output can be configured to output PD6 using the Change serial output protocol command.

Command overview

Sentences TS, BI and BD are filled with relevant numbers. All other sentences are set to zero values.

Timing and scaling data (TS)

:TS,YYMMDDHHmmsshh,SS.S,+TT.T,DDDD.D,CCCC.C,BBB <CR><LF>

Field Explanation Value
YYMMDDHHmmsshh Year, month, day, hour, minute, second, hundredths of seconds Report timestamp
SS.S Salinity in parts per thousand (ppt). Always 0
DDDD.D Depth of transducer face in meters. Always 0
CCCC.C Speed of sound in meters per second. Configured speed of sound
BBB Built-in Test (BIT) result code. Always 0

Bottom track, instrument referenced velocity data (BI)

:BI,±XXXXX,±YYYYY,±ZZZZZ,±EEEEE,S <CR><LF>

Field Explanation Value
±XXXXX X-axis velocity data in mm/s Current speed
±YYYYY Y-axis velocity data in mm/s Current speed
±ZZZZZ Z-axis velocity data in mm/s Current speed
±EEEEE Error in velocity data in mm/s Current error
S Status of velocity A = good. V = bad

Bottom track, earth referenced distance data (BD)

:BD,±EEEEEEEE.EE,±NNNNNNNN.NN,±UUUUUUUU.UU,DDDD.DD,TTT.TT <CR><LF>

Field Explanation Value
±EEEEEEEE.EE East distance in meters. Always 0
±NNNNNNNN.NN North distance in meters. Always 0
±UUUUUUUU.UU Upward distance in meters. Always 0
DDDD.DD Range to bottom in meters Current altitude
TTT.TT Time since last good velocity estimate in seconds. Always 0

Example output

:SA, +0.00, +0.00,  0.00
:TS,22061420273470, 0.0, +0.0,   0.0,1475.0,  0
:WI,    +0,    +0,    +0,    +0,V
:WS,    +0,    +0,    +0,V
:WE,    +0,    +0,    +0,V
:WD,       +0.00,       +0.00,       +0.00,   0.00,  0.00
:BI,  -167,  +211, -1770,    +0,A
:BS,    +0,    +0,    +0,V
:BE,    +0,    +0,    +0,V
:BD,       +0.00,       +0.00,       +0.00,  19.17,  0.00

Range mode configuration

Range mode configuration can be used to instruct the DVL to only search for bottom lock in a limited altitude range. This can improve performance when operating in environments where you know the DVL minimum and/or maximum altitude. (Eg when operating in a river or pool)

The format for configuring range mode can be as follows:

Range specifier Behavior
auto The DVL will search for bottom lock in it's full operational area (Default)
=a The DVL is locked to range mode a where b is a number from 0-4
a<=b The DVL will search for bottom lock within range mode a and b

The available range modes are:

Range mode Lower altitude (m) Upper altitude (m)
0 0.05 0.6
1 0.3 3.0
2 1.5 14
3 7.7 36
4 15 max

Examples:

  • =3 The DVL will search for bottom lock between 7.7 and 36m
  • 2<=3 The DVL will search for bottom lock between 1.5 and 36m