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IMCA Generic Message (Burial-Tow-Auxiliary) - 23

Description

The International Marine Contractors Association has outlined a standard protocol (IMCA S 006) for inter-vessel data telemetry.
The purpose was to define a standard for position and supplement data transfer between vessels involved in survey operations using different navigation software packages.
The standard defines a so-called Generic Message and an Anchor Spread Message.

This input driver handles the decoding of the IMCA Generic Message format.
Notice that decoding of the IMCA Anchor Spread Message is explained in the IMCA Anchor Spread Message documentation under Miscellaneous System Drivers.

The Generic Message may consist of several pre-defined data types.

The following data types are supported by this driver:

P (Position), H (Heading), R (Attitude), D (Bathy), B (Burial), T (Tow) and X (Auxiliaries).

Some other data types, like K, A and M are not supported by this driver.

Driver Information

Driver IMCA Generic Message  Interface Type Serial  Driver Class Type Terminated 
UTC Driver (question)  No Input / Output Input  Executable DrvIMCA.exe 
Related Systems
Related Pages IMCA Anchor Spread Message - 23



Decoding Notes

Driver supports the following Generic Message Data Types:

P (Position), H (Heading), R (Attitude), D (Bathy), B (Burial), T (Tow) and X (Auxiliaries).

Some other IMCA data types, like K (Stationing), A (Acoustics) and M (Messages) are not supported by this driver.

The driver does support decoding anchors from the IMCA Anchor Spread Message.
Please see the IMCA Anchor Spread Message documentation under Miscellaneous Systems.

Database Setup

  • In order to decode data type 'P' (Position), add a Position Navigation System to your template and select the driver "IMCA Generic Message (Position)" 

    Important: The object name in your template where this system is located on should be the same (case-sensitive!) as received in the IMCA "$__TEL" message (third field, i.e. the descriptor field).
  • In order to decode data type 'H' (Heading), add a Gyro and Compass System to your template and select the driver "IMCA Generic Message (Heading)"
  • Important:* The object name in your template where this system is located on should be the same (case-sensitive!) as received in the IMCA "$__TEL" message.
  • In order to decode data type 'R' (Attitude), add a Pitch, Roll and Heave Sensor System to your template and select the driver "IMCA Generic Message (Pitch and Roll)". Notice that no heave observation is part of the message. 

    Important: The object name in your template where this system is located on should be the same (case-sensitive!) as received in the IMCA "$__TEL" message.
  • In order to decode data type 'D' (Bathy), add an Underwater Sensor System to your template and select the driver "IMCA Generic Message (ROV Depth & Altitude)". Add on the 2nd wizard page a ROV Depth and a ROV Altitude observation. 

    Important: The object name in your template where this system is located on should be the same (case-sensitive!) as received in the IMCA "$__TEL" message.
  • In order to decode data type 'B' (Burial), 'T' (Tow) or 'X' (Auxiliary), add a Miscellaneous System to your template and select the driver "IMCA Generic Message (Burial, Tow, Auxiliary)". Add on the 2nd wizard page for each data type a generic observation, e.g. name one 'Burial' and set the slot id to 'B', name one 'Tow' and set the slot id to 'T', and for each auxiliary you want to decode, add an generic observation and set the slot id to '1', '2', '3', and so on.

Note.

To decode a Position, Heading, Attitude and/or Bathy, there is no need to enter a 'Slot Id' in your template setup. It is important to set the system's object (vessel) name exactly the same as received in the data string on the descriptor field.

To decode the Burial, Tow and/or Auxiliary observations, it is important to enter the right 'Slot Id':

Generic Observation

Slot Id

Burial

B

Tow

T

Auxiliary

1, 2, 3, etc...

Notice that the number of auxiliary items in the string is variable. To decode the first item, use slot id '1', to decode the second item, use slot id '2', and so on...


Online

Special notice when IMCA messages are received via radio telemetry link:

It is often seen this that telemetry updates can be very intermittent. I.e. that instead of receiving every second a nice position and/or heading updated for all the tugs involved in your survey spread, update intervals of minutes are likely to happen.
In this case, it is recommended to set the following Controller Computation Settings:

  • Select the tug object in your Computation Setup
  • Set the general filter method to None
  • Set for the COG/SOG Prediction the COG value not to Position Updates, but select the objects Heading/Gyro observation
  • Further, Enable prediction must be set to None.

Additional Information

References: IMCA S 006 Rev.1

Drivers IO Notes

Command line parameter description for "drivers.io" file.

By default the data string checksum is used to check the integrity of the received data.
Cmdline parameter 'NOCS' will disable this checking of the checksum.
Of course, this cmdline option is not recommended to use, but may be used in very rare occasions.