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RedLINE - underwater acoustic modem
Interfacing protocol specification

RedLINE
Interfacing protocol specification

Contents

1. Introduction

1.1. Physical layer

RedLINE underwater acoustic modems support data pairing using the RS-232 physical layer standard for asynchronous interface (UART) with a 3.3V data line voltage. The connection is made using a four-wire cable with Tx (transmitter), Rx (receiver), Vcc (power) and GND (ground) wires. Without the use of additional repeaters and interface converters, the maximum cable length, for which the correct operation of the interface is guaranteed, is no more than 2 meters.

Default port settings1:

Baudrate: 9600 bit/s
Data bits: 8
Stop bits: 1
Parity: No
Hardware flow control: No

WARNING! The modems are powered by 12 Volt DC source, while the data line voltage is 3.3 V.

1.2. NMEA0183 Protocol standard

The NMEA0183 standard describes the format of text (ASCII) messages at the interactive level.

Sentence example: $PTNT0,1*hh<СR><LF>

Parts of a message (sentence) NMEА0183:

2. TNT Command System for RedLINE modems

The D2H prefix in the message name means that it is transmitted from the device (Device) to the host system (Host). The H2D prefix in the message name means that it is transmitted from the host system to the device.

2.1. IC_D2H_ACK

Device acknowledgement.

Format: $PTNT0,x*hh<CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  0 Sentence ID
1 errCode Error code (see 4.1.)
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

2.2. IC_H2D_LOC_DATA_GET

Query for a local parameter value.

Format: $PTNT4,xx,00*hh<CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  4 Sentence ID
1 dataID Parameter ID (see 4.2.)
2 reserved should be ‘00’
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

2.3. IC_D2H_LOC_DATA_VAL

Device’s response to IC_H2D_LOC_DATA_GET sentence.

Format: $PTNT5,x,x<CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  5 Sentence ID
1 Requested data ID Parameter ID (see. 4.2.)
2 Value Queried value
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

2.4. IC_H2D_SETTINGS_WRITE

This sentence is used to change device’s configuration.

Format: $PTNT7,x,x,x,x*hh <CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  7 Sentence ID
1 rxChID Rx channel identifier
2 txChID Tx channel identifier
3 isRTX ‘1’ – relay mode is enabled, ‘0’ – relay mode is disabled
4 isRVRS ‘1’ – by default, the inverse channel is used for transmission, ‘0’ – by default, the direct channel is used for transmission
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

2.5. IC_H2D_SETTINGS_READ

Read current device’s settings.

Format: $PTNT8,x*hh <CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  8 Sentence ID  
1 reserved Should be always ‘0’
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

2.6. IC_D2H_SETTINGS

Current device’s settings.

Format: $PTNT9,x,x,x,x*hh <CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  9 Идентификатор сообщения
1 rxChID Rx channel identifier
2 txChID Tx channel identifier
3 isRTX ‘1’ – relay mode is enabled, ‘0’ – relay mode is disabled
4 isRVRS ‘1’ – by default, the inverse channel is used for transmission, ‘0’ – by default, the direct channel is used for transmission
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

2.7. IC_D2H_DEV_INFO

Device’s responce to IC_D2H_LOC_DATA_GET, if the queried parameter ID = LOC_DATA_DEV_INFO.

Format: $PTNT!,c--c,x,x,c--c,x,c--c<CR><LF>

Field/Parameter Description
  $ Sentence start ‘$’
  P Proprietary sentence
  TNT Proprietery code ID
  ! Sentence ID
1 System moniker System name
2 System version System version (BCD)
3 Communication subsystem moniker Communication subsystem name
4 Communication subsystem version Communication subsystem version (BCD)
5 Device type Device type (see 3.1.)
6 Serial number Serial number
  * NMEA checksum separator
  hh NMEA checksum
  <CR><LF> end of sentence

3. Service mode

RedLINE modems provide the user with a so-called “transparent channel” when all data supplied to the input without changes and analysis are transmitted to the hydroacoustic channel, after which they are received by another modem and in the unchanged form are given to the user at the receiving side. In this regard, to be able to configure modems there is a command mode. Modems analyze input data only in command mode. To switch to the command mode, the “service” core should be pulled to +3.3 V. After that, the “service” core should be pulled to the ground to exit the service mode.

WARNING! The core “service” is pulled ONLY to 3-5 V or ground, connecting it to a higher voltage will cause a FATAL and NON-GUARANTEE failure of the device.

WARNING! Before switching on the device, the “service” core should be pulled to the ground, otherwise, the device will enter the software update mode.

4. Identifiers

4.1. Error codes

Error Value Description
LOC_ERR_NO_ERROR 0 Request accepted
LOC_ERR_INVALID_SYNTAX 1 Syntax error
LOC_ERR_UNSUPPORTED 2 Request not supported
LOC_ERR_TRANSMITTER_BUSY 3 Transmitter is busy
LOC_ERR_ARGUMENT_OUT_OF_RANGE 4 Specified parameter out of range
LOC_ERR_INVALID_OPERATION 5 Invalid request
LOC_ERR_UNKNOWN_FIELD_ID 6 Unknown field identifier
LOC_ERR_VALUE_UNAVAILIBLE 7 Requested parameter is not available at the moment
LOC_ERR_RECEIVER_BUSY 8 Receiver is busy

4.2. Local data identifiers

Value Identifier Description
0 DEVICE_INFO Device information
2 MAX_SUBSCRIBERS Max. number of code channels available
6 PRESSURE_RATING Max. external hydrostatic pressure in Bars

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