New Plugin NmeaConvertor

[LennartG]

Thanks Dirk for your prompt reply,
I am well aware of the difference and that is why I am generating an 'XXHDM' based on the first field in 'HDG and adding an 'M', omitting the other fields in HDG.

$--HDM,x.x,M*hh<CR><LF>Field Number:

1. Heading Degrees, magnetic
2. M = magnetic
3. Checksum

/LennartG

[rooiedirk]

But in nmea you are not free to simple omit data fields. It is a fixed data structure.
You may leave fields empty though, so
$XXHDM,$ECHDG1,,,,
should also be valid.

[LennartG]

Dirk,
as I read it 'HDM' only has three fields and I have supplied all three. What you are suggesting is 'extending' the HDM with additional fields from HDG.
I will try that later as I'm a bit busy right now.
/LennartG

[rooiedirk]

Originally Posted by LennartG

Dirk,
as I read it 'HDM' only has three fields and I have supplied all three. What you are suggesting is 'extending' the HDM with additional fields from HDG.
I will try that later as I'm a bit busy right now.
/LennartG

Oops, you are right
Your commandsentece should work. Is there something in the log to help find out what's going on?

[LennartG]

Dirk,
the logs are empty (regarding this 'happening'). I have tried this on both 4.8.8 and 4.9.9 with exactly the same result. Running Ubuntu 16.04 XFCE.
My guess is that 'HDM' somehow is not 'enabled', it is not in the list on the NmeaConverter documentation pages. It is however used for the Dashboard magnetic heading and is listed as such in the OpenCPN 'NMEA 0183 Sentences', section 'Dashboard Plugin'.
Otherwise: Not a clue, not being a programmer but former system administrator.
/LennartG

[rooiedirk]

A quick test here works as it should be.

[LennartG]

Dirk,
this was really odd!
Using the same signals as in the picture and assuming that:
message 0 is sent after update
message 1 is generated once per second
it works just fine here as well!

Now adding the ECHDG from an external source (replacing signal '1' in the picture) causes OpenCPN to hang. The external signal used is 'ECHDG,184.4,,,6.6,E', completely valid and generated thru gpsfeed+.

The error: Not in NmeaConverter nor OpenCPN but a bug in gpsfeed+ that calculates the checksum the wrong way!

Line 1901 (about) in the tcl-script should read 'return [format %02X $xor]', the '02' was omitted causing the checksum to be in error. That together with OpenCPN hanging (feels a bit drastic though) fooled me completely!

Thanks for your assistance and effort
/LennartG

[odonnellryan]

Hi!

Awesome plugin. I am having one issue with wind data: it seems like the wind data is being sent too quickly? Basically only 1 our of 4-5 of the messages are being updated as I want them to (I'm changing the wind angle). Am I doing something wrong? Is there a way I can have OpenCPN ignore the other sentence?

[rooiedirk]

Some more info please. What exactly is your input, what is your command sentence and what is the output. And what is the desired ouput.

[odonnellryan]

Rooiedirk, I don't have the exact data right now (not on the boat) but it is essentially:

Input (from wind device which goes to another Pi device (PyPilot) which is then sent to the main OpenCPN device):

$ARMVW,10,R,1.1,M*a1

Command sentence (just trying to change the degrees by 120 about):

$xxMVW,$ARMVW1+120,$ARMVW2,$ARMVW3,$ARMVW4,$ARMVW5

Output is correct, it would look like this:

$ARMVW,130,R,1.1,M*a1

Which is the desired output.

HOWEVER, I'll get multiple inputs sent before getting an output (it is NOT on the 1 sentence a second setting).

I thought this might have been because in the docs it is mentioned "update will be sent after every variable has changed" but I'm not sure if that means anything?

My other option is to change this on the other device, the PyPilot. Maybe that would work? That is more effort and I'd rather not take it out of the case etc.. that I have it installed in if I don't need to.

[rooiedirk]

If I use the same plugin to send "$ARMVW,10,R,1.1,M" every second, and "$xxMVW,$ARMVW1+120,$ARMVW2,$ARMVW3,$ARMVW4,$ARMVW 5" upon received all data, it works just nice here.
All I can think off: Are your incoming checksums OK, and didn't you make a typing error?

[odonnellryan]

Originally Posted by rooiedirk

If I use the same plugin to send "$ARMVW,10,R,1.1,M" every second, and "$xxMVW,$ARMVW1+120,$ARMVW2,$ARMVW3,$ARMVW4,$ARMVW 5" upon received all data, it works just nice here.
All I can think off: Are your incoming checksums OK, and didn't you make a typing error?

I did that test too! Works fine, I figured because the frequency of the messages is just 1 second. The messages from the windvane come in bursts.

The wind direction changes fine - the issue is it "jumps" on the dashboard between my 2 directions. Usually it stays on the "bad" direction because the signals go like this:

$ARMVW ....
$xxMVW ....
$ARMVW ....
$ARMVW ....
$ARMVW ....


So you'll get the one good one, changes that one, then you get 4 other signals which cause the "bad" direction to stick in the dashboard until the next update.

I can browse through the code at some point. I thought it just may have been a user error or something. I don't want to waste time if it is something more complicated

> Are your incoming checksums OK, and didn't you make a typing error?

Not sure actually how to check checksums, I'll have to do that. But like I said it does work - but the frequency of the messages causes the other value to be the one that is mostly displayed.

[keoe]

Hi,

I want to convert HDM to HDT to get the right heading of the ship symbol (my compass is adjusted for the magnetic variation). Unfortunately my knowledge about NMEA sentences is too low to achieve that.
Is there anyone that could helpe me?

[Moo]

Originally Posted by keoe

Hi,

I want to convert HDM to HDT to get the right heading of the ship symbol (my compass is adjusted for the magnetic variation). Unfortunately my knowledge about NMEA sentences is too low to achieve that.
Is there anyone that could helpe me?

That is not something that you would generally do. Your compass is usually adjust for deviation (the error) and you can adjust for declination but this can only ever be temporary as it changes continually.



What compass is producing the HDM sentance? Can it be set to transmit True? otherwise True is Mag + Variation (E) + Deviation

[keoe]

Originally Posted by Moo

That is not something that you would generally do. Your compass is usually adjust for deviation (the error) and you can adjust for declination but this can only ever be temporary as it changes continually.



What compass is producing the HDM sentance? Can it be set to transmit True? otherwise True is Mag + Variation (E) + Deviation

I am fully aware of what magnetic variation and deviation means. In the area where I sail, the Magnetic variation is small and the annual change is less than 0.1 degrees per year.

Since it not possible to set the compass to send the HDT message, I want to convert HDM to HDT. Is that possible via the NMEAConverter plugin?