NMEA4 / SailGrib

Discussion and support for the Nmea4Wifi multiplexer - a 4-input Nmea 0183 wifi multiplexer.
Bakoua
Posts: 2
Joined: Fri Nov 27, 2020 6:13 pm

NMEA4 / SailGrib

Post by Bakoua » Sat Nov 28, 2020 10:21 pm

Hello
Any body using SailGrib with the multiplex NMEA4 ?
We are a few that have problems connecting our WiFI with sailgrib
so if you are using it can you share the settings ?

Thanks

Bakoua
Posts: 2
Joined: Fri Nov 27, 2020 6:13 pm

Re: NMEA4 / SailGrib

Post by Bakoua » Tue Dec 01, 2020 3:21 pm

Hello
Well I found the way to make it work for my AIS
on the multiplex leave the settings as they are
just make sure the Bds rate is according to the source
(on mine it was the AIS from My VHF at 38400)
leave 0 on the setting of P1 and make sure it's on UPD
the WIFI port should be on 2000

On sail Grib
start the NMEA
set the source on "autre"
set the protocole UDP
IP adresse 192.168.4.1
Port du serveur 2000
and it should work
I only had AIS on P1 next I'm gonna try to get the external GPS on P2
and then to enter the seatalk signal...
I'll let you know...
Take care of you all
Dom

Bruno
Posts: 10
Joined: Wed Jul 21, 2021 8:01 am

Re: NMEA4 / SailGrib

Post by Bruno » Wed Jul 21, 2021 9:33 am

Hi,

My navigation s/w Sailgrib routing S/W (excellent btw!) has only one issue with my old Raymarine S1:

w/ the last version of Sailgrib or previous ones it does not recognize HDM
which is the only one NMEA sentence relevant to the boat heading
provided by S1, which also sends incomplete formats for others (VHW, HDT and HDG)
that Sailgrib can recognize.

It is connected to the S1 NMEA out (P2 on N4W). I tested adding the Seatalk S1 port (P4 on N4W),
which doubles some sentences (with a different source though), but as some are not on both channels
this ensures not to miss available data, but the problem stays.

While waiting for HDM to be added in future releases, I need to create and send to Sailgrib
one of the recognized sentences.

In order to avoid inserting an additional Arduino or equivalent in the flux,
I was thinking of writing an app to be run in the navigation tablet, that would connect
and receive the flux from N4W, compute the required sentence(s) from the others,
and send them out on P5, which I would bridge to eg P3 to reinsert the new
sentence(s) in the flux.

Any better/simpler solution? (of course there are with modifying the N4W code, but that is a different story!)

Thanks
Bruno

Luis Sa
Site Admin
Posts: 847
Joined: Thu May 04, 2017 4:12 am

Re: NMEA4 / SailGrib

Post by Luis Sa » Wed Jul 21, 2021 9:55 am

Hello Bruno,

I would be very happy to change the software with your input but unfortunately I am in Greece until mid September. If you can wait, we could discuss this later.

Sorry for the lack of assistance, Luis

Bruno
Posts: 10
Joined: Wed Jul 21, 2021 8:01 am

Re: NMEA4 / SailGrib

Post by Bruno » Wed Jul 21, 2021 10:11 pm

Hello Luis,

Waooo, that is a great offer! I don't know when Sailgrib will take this into account.
I had a great mail exchange with Henri on this and a few other points, he is aware
of the problem.

Let's get in touch in late September and see ho things are.
I wish you a superb navigation in Greece,

Cheers,
Bruno

dagnall
Posts: 459
Joined: Wed Mar 04, 2020 6:36 pm

Re: NMEA4 / SailGrib

Post by dagnall » Thu Jul 22, 2021 11:41 am

Bruno, (Luis)
I spotted this post whilst looking for HDM stuff because it is of interest in the Bidirectional NMEA3 code we (Luis and I) are exploring. (Mainly me playing while Luis is in Greece!.. I hope to get sailing soon as well, but some parts have not arrived).

Can you give me a little more information about what NMEA data Sailgrib CAN accept? This is not one of the navigation programs that I am familiar with. I am actually just about to possibly add an extra conversion into the Seatalk to Nmea HDM / HDG coding.

You mention that you have a Raymarine S1, (so do I). I believe that the S1 outputs Seatalk datagrams 84 and 9C (see Thomas Knauf's guide).. These datagrams actually include a lot more information which does not easily translate into HDM/HDG NMEA messages. (which is why I was looking at them today!).
Is it possible you could capture (use the debug mode) a little data from both the Seatalk and NMEA out puts of the S1- ideally with the autopilot both in standby and in auto mode (this changes which datagrams are sent). This would help development in future.

It may be possible to make a new seatalk to nmea conversion that is more acceptable to sailgrib?


All the very best
Dagnall

Bruno
Posts: 10
Joined: Wed Jul 21, 2021 8:01 am

Re: NMEA4 / SailGrib

Post by Bruno » Mon Sep 27, 2021 5:36 am

Hi Dagnall,

I am no expert. As I wrote in my July post, I only checked by sending sequences to Sailgrib, the for the boat heading (angle of the boat to North,not the course), that Sailgrib does decode correctly VHW, HDT and HDG. It does not read HDM in the present version. I sent this info to Henry, who may add it in a next release, but with no commitment in time. I have no ways to direcly decode Seatalk.

Bruno

Bruno
Posts: 10
Joined: Wed Jul 21, 2021 8:01 am

Re: NMEA4 / SailGrib

Post by Bruno » Mon Sep 27, 2021 5:39 am

Hi Luis,

I wish you enjoyed your navigation in Greece. In case you are safely back (which I hope !), I am still interested in the s/w modification you offered in your Wed Jul 21, 2021 10:55 am post.

Please let me know if and how this could be achieved.

Take care,
Bruno

dagnall
Posts: 459
Joined: Wed Mar 04, 2020 6:36 pm

Re: NMEA4 / SailGrib

Post by dagnall » Fri Jan 21, 2022 1:48 pm

(EDITED.. See "EDIT" in the text)
Bruno
I tried to send an Email, but apparently my message got rejected and was undelivered.
I am now looking at your issue again, but responding through the forum.

I would like to first confirm that we understand the issue with SailGrib:
  • Sailgrib does not recognise HDM
  • but does recognise VHW HDT HDG
  • You have seatalk instruments (?) and a Raymarine S1 smart pilot.
  • You would like us to generate a HDG message when we currently send HDM?
I also have a Raymarine Pilot that gives me Compass headings.
  • Compass headings received by a NMEAxWiFi multiplexer will be converted to EITHER a HDM or a HDG message, depending on whether the NMEA multiplexer has been advised (via SeaTalk) of the local Magnetic Variation.
  • The "SeaTalk" Magnetic Variation is obtained from the Seatalk datagram "99".
    • This is normally sent only if Magnetic Variation has been set in the ST40 (compass) instrument.
  • So if no (SeaTalk) Magnetic variation is known, then the Multiplexer will only send out HDM messages. (which apparently Sailgrib does not understand).
In newer NMEA3WiFI models, we can convert NMEA into Seatalk. So if the GPS is routed to Seatalk, then the GPS RMC message is converted to multiple datagrams, (including the key "datagram 99" that includes the advised magnetic variation for the area). Thus the "Seatalk" side of the multiplexer is informed of magnetic variation and will send out HDG..

EDIT.. There is a fault in my logic / our code... .. The reception of a RMC message DOES trigger "Sending" of a 99 (magnetic variation) message, BUT the code DOES NOT internally set the "magnetic variation is known" flag... So any compass reading is still sent as HDM
I suspect we need to revise the code so that NMEA RMC data (if received) will pass magnetic variation data to the SeaTalk "side" of the units. - Without having to have seen a Datagram 99 message.

Luis and I need to discuss this when he gets back from Greece, as it we would not want to introduce any possibility of data corruption, but it looks like a reasonable idea!

Dagnall

Bruno
Posts: 10
Joined: Wed Jul 21, 2021 8:01 am

Re: NMEA4 / SailGrib

Post by Bruno » Sun Jan 23, 2022 5:40 am

Hi Dagnall,

In complement of our email exchanges:

Thanks a lot. Your summary is exact.

My instruments mostly send NMEA data, and the course computer sends all of its data on both its NMEA and Seatalk Out Ports, so I can use any (and I have actually connected both).

At least when not provided, the declination is calculated by Sailgrib from location and date. I didn't check what is used when one gives it or gives both HDM and HDT.

Besides, I seem to remember there is at least one sentence I can see in only one of the 2 output fluxes of the computer in Sailgrib.


Best
Bruno

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