When latitude and longitude are null, this message is being repeated on the server log:

Sep 25 20:31:54 invalid input to toNmeaDegreesLatitude: null

They were added in #1 but seem to be left out in a refactoring

If I have RMC conversion active in my system, with nmea0183 going out to 4800 baud 0183 connection, the cpu will go up to 100%. Deactivating RMC conversion will bring it back down, but after a while, not immediately.

key should be 'environment.wind.angleTrueWater' or 'environment.wind.angleTrueGround'

I'm trying to have all data connection managed by signalk. I'm doing eveything in a test environment at home before tranferring to the boat. In this environment the autopilot serial connection is connected to a PC acting as a monitor (via putty serial) to see the Nmea183 sentences coming out from the SBC (a raspi clone) hosting signalk server.

The route info is coming from an external chartplotter app (in this environment an android phone with AvNav app installed). The GPS info is coming from a GPS mouse connected to Signalk and the app receives the GPS info from signalk (the internal smartphone GPS is disabled) via a TCPReader connected to signalk IP on port 10110.

The Avnav app manages the route and wp stuff generating the required autopilot info (RMB and/or APB) when a wp/route is engaged. The nmea output coming from the app is forwarded back to signalk via an UDP writer connection to signalk IP on port 28628.

If the plugin is set to send $XTE (plus other GPS sentences like $RMC or $VTG) everything works fine and the sentences are well read on putty window. The XTE info is obtained by signalk from the RMB sentence received from the AvNav app (in fact the signalk paths relative to this info are listed in signalk having as source the back connection ID plus the RMB sentence). So far so good.

But if I try to enable RMB in the plugin nothing happens and the RMB sentence is NEVER output from signalk even if all the necessary info is available. I tried also with APB with the same unsuccess.

I saw from issue #60 that there are invalid data path that the plugin uses to gather the wp lat/lon info and I tried to patch both the nmea0183 RMB hook (generating two new paths navigation.courseRhumbline.nextPoint.latitude and navigation.courseRhumbline.nextPoint.longitude) and the sentences/RMB.js to take into account the new keys with no success.

Since RMB is a very useful sentence to get out in a navigation system I think it was well debugged in previous version of the plugin and I suspect that something (update of the schema?) yelded a regression. The release of signalk I'm using is the latest (I believe). The release number is 1.46.3

The Plug-in is installed by default and even though in plugin settings with it disabled it appears to be running anyway.

https://www.tronico.fi/OH6NT/docs/NMEA0183.pdf

RPM Revolutions

       1 2 3   4   5 6
       | | |   |   | |
$--RPM,a,x,x.x,x.x,A*hh
1) Source; S = Shaft, E = Engine
2) Engine or shaft number
3) Speed, Revolutions per minute
4) Propeller pitch, % of maximum, "-" means astern
5) Status, A means data is valid
6) Checksum

I do not get speed through water in OpenCPN when running the SignalK to NMEA183 converter. Most other data is OK. I'm using the converter to feed the Polar diagram recorder (also tested VDR, which works ok, but no STW). The speedThroughWater signalK works fine, display nicely on the instrument panel web app and OpenCPN dashboard. I do not find a tick box for VHW on the plugin config, but the file VHW.js exists and there is a reference to speedThroughWater in that file. I have also redirected the NMEA183 sentences to a file and searched for VHW without finding any.

It would be nice to have the Polar diagram based on speed though water in addition to speed over ground reference. Any possible fix for this ?

Many apps receive the GPS location, but the Navionics Boating app doesn't.
When i look at the data (source are sample files from /opt/signalk-server/samples/) i see sentences with an $II prefix instead of $GP, for example:

$IIGGA,190048,5943.4074,N,02444.1567,E,1,11,0.8,2.26,M,0,M,,4E
$IIGLL,5943.4074,N,02444.1567,E,210048.020,A21
$IIRMC,190048,A,5943.4074,N,02444.1567,E,6.7,187.3,150814,8.1,E*66

That doesn't seem to work for Navionics. If i use the standart gps.log sample (/opt/signalk-server/samples/), for some reason the output also includes $GP prefixed sentenced. And that does work, see example below.

$GPGGA,085609.000,5222.3257,N,00454.5851,E,1,6,1.18,15.1,M,47.0,M,,6E
$IIGGA,085608,5222.3257,N,00454.5851,E,1,6,1,15,M,0,M,,73
$IIGLL,5222.3257,N,00454.5851,E,105608.020,A23
$IIRMC,085608,A,5222.3257,N,00454.5851,E,0.8,248.0,030414,0.0,E6E
$GPGSA,A,3,02,16,23,13,29,07,,,,,,,1.48,1.18,0.890C
$GPRMC,085609.000,A,5222.3257,N,00454.5851,E,0.81,248.69,030414,,,A6E

Questions:

• in the source i see that signalk-to-nmea0183 is creating these $II prefixed sentences, why is that?
  I do see that Shipmodul can do the same, so i guess the prefix shouldn't matter for the consuming app: http://www.shipmodul.com/downloads/manuals/legacy/miniplex-42.pdf, page 9 Talker ID

• If this is according to the standard, than still widely used apps like Navionics can not use this. Would it be possible to make this configurable? Similar to how Shipmodul is doing this for example? Or just a switch to use either $II or $GP?

There is a bug in the signalk-to-nmea0183 plugin when writing the GLL sentence:

        1       2 3        4 5         6 7
        |       | |        | |         | |
 $--GLL,ddmm.mm,a,dddmm.mm,a,hhmmss.ss,a*hh<CR><LF>

5 must be time in UTC of this position, hh is hours, mm is minutes, ss.ss is seconds

But the plugin is writing just local time into the sentence instead which leads to several problems.

The RMC sentence also has the UTC of the position and there it is implemented correctly.

The fix should be straigt forward in getting the timestamp in the same way as for the RMC sentence

Hi,

I don't use GitHub very often so I'd appreciate any advice on where to post questions like the following!

A Bit Of Background:

I would like n2k-to-signalk to send the 129029 PGN to signalk-to-nmea0183 and output GGA and ZDA to my laptop (which reads incoming messages) via USB.
I know this can be done by a regular converter like the NGW-1, but my intention is to familiarise myself with SignalK so that I can create the plugin to convert the 128520 PGN to the TTM sentence in the future, as to the best of my knowledge this is not supported at the moment.

My Questions:

1. I have been using the sample n2k messages and I can see them coming in on the signalk dashboard, but how do I know if they are being converted to the signalk format?
2. Once the n2k messages are converted to the signalk format, how do I setup signalk-to-nmea0183 to convert these to NMEA 0183 and transmit these to the USB port?
3. Any advice for how to approach the custom plugin?

Thanks in advance!

I could set notification and reset alarms at SignalK (using Node-Red), example for man over board:

Set:
Path: notifications.mob
Value: {
"state": "emergency",
"method": [
"visual",
"sound"
],
"message": "Person über Bord!"
}
Reset:
Path: notifications.mob
Value: null

Unfortunatly I could find no way to make it usaable for instance for OpenCPN or AvNav via the plugin.
I found some NMEA0183 sentences ACK ,AKD, ALA here:

but with no description.
Would be great to have a biderectional alarm communication between the plotters and SignalK.

Thank you for your development so far.

My SITEX N2K AIS with GPS does not put out a COG when at standstill. That seems to cause this plugin to not put out a RMC sentence.

Use case: I have some old wxtoimg sat-image receiving system that needs to have RMC as ground station location. When the boat is not moving, it fails to get the lat/lon, since no RMC is received

Could the need for COG be made dependent on having a SOG>0, otherwise just plug a zero into COG?

I appreciate the VWT sentence is deprecated but the parameters are incorrect. The wind angle should be relative to the boat (0-180 degrees) and the next parameter either L or R (for port or starboard)

I have I2C connected humidity/temp/pressure sensor (BME860) to get data into SignalK and out again to the NMEA0183 network. I have the signalk-raspberry-pi-bme860 plugin and that brings data into SignalK. I want to use signalk-to-nmea0183 to get the data out to the NMEA0183 network (wifi)

I would like map the following (out from signalk-raspberry-pi-bme860) to an MDA sentence?

environmental.inside.humidity
environmental.inside.pressure
environmental.inside.temperature

In VHW.js

From the documentation on https://signalk.org/specification/1.5.0/doc/vesselsBranch.html

Description: The magnetic variation (declination) at the current position that must be added to the magnetic heading to derive the true heading. Easterly variations are positive and Westerly variations are negative (in Radians).

key should be environment.wind.angleTrueWater

RMB.js specifies the following keys..

sentence: 'RMB',
    title: 'RMB - Heading and distance to waypoint',
    keys: [
      'navigation.courseRhumbline.crossTrackError',
      'resources.waypoints.next.position.latitude',
      'resources.waypoints.next.position.longitude',
      'navigation.courseRhumbline.nextPoint.distance',
      'navigation.courseRhumbline.bearingTrue'
    ],
...

the keys resources.waypoints.next.position.latitude and resources.waypoints.next.position.longitude are not part of the spec.

I would suggest that these keys should be replaced with navigation.courseRhumbline.nextPoint.position.

Also the use of courseRhumbline vs courseGreatCircle should be reviewed for consistency across sentences (APB uses courseGreatCircle). Additionally signalk-derived-data plugin populates courseGreatCircle paths.

Hi,

now GGA sentence looks:
$IIGGA,085210,5408.7630,N,01328.9580,E,DGNSS fix,8,1,0,M,0,M,,*60

7th field is wrong. It must be numeric

GGA - Global Positioning System Fix Data, Time, Position and fix related data fora GPS receiver.

                                                  11
    1         2       3 4        5 6 7  8   9  10 |  12 13  14   15
    |         |       | |        | | |  |   |   | |   | |   |    |

$--GGA,hhmmss.ss,llll.ll,a,yyyyy.yy,a,x,xx,x.x,x.x,M,x.x,M,x.x,xxxx*hh

Field Number:

1. Universal Time Coordinated (UTC)
2. Latitude
3. N or S (North or South)
4. Longitude
5. E or W (East or West)
6. GPS Quality Indicator,
   0 - fix not available,
   1 - GPS fix,
   2 - Differential GPS fix
7. Number of satellites in view, 00 - 12
8. Horizontal Dilution of precision
9. Antenna Altitude above/below mean-sea-level (geoid)
10. Units of antenna altitude, meters
11. Geoidal separation, the difference between the WGS-84 earth
    ellipsoid and mean-sea-level (geoid), "-" means mean-sea-level
    below ellipsoid
12. Units of geoidal separation, meters
13. Age of differential GPS data, time in seconds since last SC104
    type 1 or 9 update, null field when DGPS is not used
14. Differential reference station ID, 0000-1023
15. Checksum

A slightly modified README.md doc with reference to the default TCP output and clarifying the required changes to settings.json file
README.zip

We do the reverse in the parser module, why not here too? Also, I'd actually need it for my use-case.

The APB sentence is not emitted even when all of the rquired paths navigation.courseGreatCircle.crossTrackError, navigation.courseGreatCircle.bearingTrackTrue and navigation.courseGreatCircle.nextPoint contain data.

To reproduce:
requires signalk-derived-data, freeboard-sk-helper, sk-resources-fs plugins installed and configured.
Using Freeboard select navigate to a location, Waypoint or activate a route to populate nextPointPosition and have the derived-data plugin to calculate the XTE, bearingTrue values.

In my testing the only sentence emitted was RMC.

Request to add conversion to GSV

GSV - Satellites in View shows data about the satellites that the unit might be able to find based on its viewing mask and almanac data. It also shows current ability to track this data. Note that one GSV sentence only can provide data for up to 4 satellites and thus there may need to be 3 sentences for the full information. It is reasonable for the GSV sentence to contain more satellites than GGA might indicate since GSV may include satellites that are not used as part of the solution. It is not a requirment that the GSV sentences all appear in sequence. To avoid overloading the data bandwidth some receivers may place the various sentences in totally different samples since each sentence identifies which one it is.

The field called SNR (Signal to Noise Ratio) in the NMEA standard is often referred to as signal strength. SNR is an indirect but more useful value that raw signal strength. It can range from 0 to 99 and has units of dB according to the NMEA standard, but the various manufacturers send different ranges of numbers with different starting numbers so the values themselves cannot necessarily be used to evaluate different units. The range of working values in a given gps will usually show a difference of about 25 to 35 between the lowest and highest values, however 0 is a special case and may be shown on satellites that are in view but not being tracked.

$GPGSV,2,1,08,01,40,083,46,02,17,308,41,12,07,344,39,14,22,228,45*75

Where:
GSV Satellites in view
2 Number of sentences for full data
1 sentence 1 of 2
08 Number of satellites in view

  01           Satellite PRN number
  40           Elevation, degrees
  083          Azimuth, degrees
  46           SNR - higher is better
       for up to 4 satellites per sentence
  *75          the checksum data, always begins with *

Via TCP I am receiving the following sentences
GGA,GLL,RMC,DBK,DBS,DBT,HDG,HDM,HDT,MTW,MWD,MWV,VHW,VWR,VWT,ZDA

Via Serial output I am only receiving the following, all the output types are ticked in the plugin config.
GGA,GLL,RMC,HDG,HDM,HDT

Server v1.35.2 Plugin v1.7.1

Hello,
I want to send nmea0183 data using signalk and using this plugin. I read this and I think this is just what I need, however I still do not know how to actually send something back trought my serial connection.

I have bidirection rs232/483 connection and I can read, now I want to write.

I have install this plugin, now I want to send a value for the HSC pgn for example...

What would be the end 2 end steps!?

Thanks in advance!

According NMEA0183 Documentation you swapped the position of Variation field with Deviation field!

HDG - Heading - Deviation & Variation

    1   2   3 4   5 6
    |   |   | |   | |

$--HDG,x.x,x.x,a,x.x,a*hh

Field Number:

1. Magnetic Sensor heading in degrees
2. Magnetic Deviation, degrees
3. Magnetic Deviation direction, E = Easterly, W = Westerly
4. Magnetic Variation degrees
5. Magnetic Variation direction, E = Easterly, W = Westerly
6. Checksum

Greeting from Norway :)
Im playing with openplotter on a boat with a nmea2000 bus, signal k receives data (through actisense ngt-1), but I haven't managed to forward those data to opencpn. I thought I could use signalk-to-nmea0183 for this task, writing to a serial device, and setup opencpn to read from this. Is this the intended way? If so - do I create a new serial port on the rpi, and set "device" in the signalk config to this?
Best regards
Kai

GSA - GPS DOP and active satellites. This sentence provides details on the nature of the fix. It includes the numbers of the satellites being used in the current solution and the DOP. DOP (dilution of precision) is an indication of the effect of satellite geometry on the accuracy of the fix. It is a unitless number where smaller is better. For 3D fixes using 4 satellites a 1.0 would be considered to be a perfect number, however for overdetermined solutions it is possible to see numbers below 1.0.

There are differences in the way the PRN's are presented which can effect the ability of some programs to display this data. For example, in the example shown below there are 5 satellites in the solution and the null fields are scattered indicating that the almanac would show satellites in the null positions that are not being used as part of this solution. Other receivers might output all of the satellites used at the beginning of the sentence with the null field all stacked up at the end. This difference accounts for some satellite display programs not always being able to display the satellites being tracked. Some units may show all satellites that have ephemeris data without regard to their use as part of the solution but this is non-standard.

$GPGSA,A,3,04,05,,09,12,,,24,,,,,2.5,1.3,2.1*39

Where:
GSA Satellite status
A Auto selection of 2D or 3D fix (M = manual)
3 3D fix - values include: 1 = no fix
2 = 2D fix
3 = 3D fix
04,05... PRNs of satellites used for fix (space for 12)
2.5 PDOP (dilution of precision)
1.3 Horizontal dilution of precision (HDOP)
2.1 Vertical dilution of precision (VDOP)
*39 the checksum data, always begins with *

I am trying to display data from the SignalK server running on a pi on my old stowe Dataline instruments, with Dataline being an early take on NMEA0183 as I understand. They are receiving the data, however are expecting a slightly different format, i.e. the VHW sentence from this plugin outputs XXX.X, M for the magnetic heading while the instruments expect XXX, M without a decimal. At the moment I am getting values on the screen, but apart from the STW they are alll wrong and some of them going all over the place each time the display is updated.
Is there a way I am not aware of to adjust the format? Otherwise it would be a great feature.
I would love to help as much as I can but have no experience at all with javascript.