OpenCPN and external NMEA0183 alarms

[FWallenwein]

Hi Folks,

I'm looking for a way to somehow feed external alarm conditions to OpenCPN via NMEA0183, and to display or even acknowledge this alarms.

Let me explain what I'm looking for.

I have some seatalk instruments, that can emit alarms.
Things like "Depth transducer defective", "Wind shift alarm"," Radar monitoring alarm", "gps failure" etc.

I have built a multiplexer with bridge function, that converts seatalk data into NMEA. This NMEA data are than feed to openCPN.
That works well with "normal" data and "normal" NMEA sentences. Things like depth, speed, postion, waypoint ....

But now I'm looking for a NMEA sentence, that represents different alarm's.

It would be great, if openCPN could display this external alarms and maybe even offer a button for alarm acknowledge.
The acknowledge could be sent from the PC to the converter and back to the seatalk devices.
This would require another NMEA sentence for alarm ack.

- Does anyone know of a "Alarm-Nmea-Sentence" and a "Alarm-Acknowledge-Sentence" ?

- If we should find such a sentence - any Ideas on how to implement this functions into openCPN ?

- Would something like that be interesting to other OpenCPN users ? Or am I the only one who would like have it ?

Thank's for any ideas.

Frank

[nohal]

Frank...
It seems there used to be PNATD sentence created by old versions of the "official" Seatalk-NMEA bridge (http://www.busse-yachtshop.de/pdf/se...-interface.pdf, but as usually there's nothing more than that the sentence exists) - in the recent Raymarine docs you won't see it mentioned anymore.
You will probably have way more luck doing it with ALR/ACK as used in some other applications, the following taken from AIT250 manual:

AIS Alarm Messages (NMEA 0183 ALR, Text)
ALR message format
$--ALR,hhmmss.ss,xxx,A,A,c--c*hh<CR><LF>
Where
• hhmmss.ss = Time of alarm (UTC)
• xxx = Unique alarm number
• A = Alarm condition
• A = Alarm acknowledge state
• c--c = alarm description, text
Alarms descriptions presented are:
• AIS: TX malfunction
• AIS: Antenna VSWR exceeds limit
• AIS: Rx channel 1 malfunction
• AIS: Rx channel 2 malfunction
• AIS: general failure
• AIS: no sensor position in use
• AIS: no valid SOG information
• AIS: no valid COG information
• AIS: 12V alarm
• AIS: 5V alarm
• AIS: Loss of serial interface integrity
• AIS: Background noise above -77dBm
ACK messages
Can be generated by a minimum keypad and display (MKD) unit, chart plotter or other display device connected to the SRTMTB
to acknowledge an alarm condition reported by the SRT-MTB.
ACK message format
$--ACK,xxx*hh <CR><LF>
Where
• xxx = unique alarm number

Implementing reading such a sentence and doing whatever based on it's contents in a plugin will be close to trivial. Data output less so until we will have a revamped serial I/O infrastructure and API in place.

Pavel

[FWallenwein]

Originally Posted by nohal

Implementing reading such a sentence and doing whatever based on it's contents in a plugin will be close to trivial. Data output less so until we will have a revamped serial I/O infrastructure and API in place.

All right. Thank you for the info.
I guess I'll start trying to make a plugin using the ALR/ACK sentence.
ALR at first, ACK woud require NMEA output.

I think it would be nice to use the alarms from the instruments and use the alarm settings made in the instruments.

Looking forward to read about news regarding revamped serial I/O infrastructure in the future.

Thank's
Frank

[nohal]

Frank...
Have a look at the NMEA stuff in the dashboard plugin - will get you half way without any effort... Another cannibalized version of it with less code around in https://github.com/nohal/survey_pi

Good luck

Pavel