NMEA2000 EGT, gbox oil pressure, etc DISPLAY??? My Garmins don't work :(

[vas]

Dear all,

another question/rant on my favourite topic...

I’ve finished my main Arduino black box doing all sorts of conversions to NMEA2K as well as simulating AutoAnchor's 601 black box. All that’s gone smoothly (almost) and work with data presented on GMI10s and/or GPSMAPs chartplotters.

So now decided to do one smaller black box for each engine (to be fitted in the e/r) and do the following:

• EGT
• Seawater temp when reaching the exhaust elbow (or alternatively exhaust temps after the elbow)
• Gearbox oil pressure
• CAC air temp
• Plus anything else I can think off (would like fuel consumption, but turns out to be a v.difficult job)

Anyway, got a dozen sensors plus a few exhaust K-type thermistors to play…

Now, prototyped a few of these NMEA2000 sentences, tested them this evening and hit a nasty wall:

EGT exists as a NMEA2000 sentence but none of the Garmins I own lists it (GMI10, GPSMAP4008 and GPSMAP751)
Second exhaust temp doesn’t even exist so I have to use another temp (dunno bait, or something silly) to map it on… and I'd need two of them
Gearbox oil pressure has a max value of 200psi (on the GMIs, the GPSMAPs don’t know it at all…), FFS, my twin disk box works at 300-360psi, what were they thinking???
CAC is not even listed as a NMEA2000 sentence.

So Q to you:
Where do you present that sort of info? I'm not talking about you ECU equipped guys with fancy multiscreen displays, I'm talking manual diesel engines here.
I always thought that gauges/plotters pickup new sentences when they appear in the bus and present them (maybe next reboot...), doesn't seem to be the case here!
Regarding the EGTs, the following types of temps are documented (in NMEA docs):
SeaTemperature
OutsideTemperature
InsideTemperature
EngineRoomTemperature
MainCabinTemperature
LiveWellTemperature
BaitWellTemperature
RefridgerationTemperature
HeatingSystemTemperature
DewPointTemperature
ApparentWindChillTemperature
TheoreticalWindChillTemperature
HeatIndexTemperature
FreezerTemperature
ExhaustGasTemperature
Garmin GMIs supports the 14 first and doesn’t do the last which I need!
Also getting a higher upper limit to the gearbox oil pressure is a must.

I've also asked JFM maybe I can use his contacts and ask/suggest some updates (upping the gbox oil pressure limit is dead simple, showing it on either plotters engine screens is a bit trickier I suppose), we'll see.

And Q to others, how do you show such data (especially on the f/b where typically you don't get all the gauges you have on the lower helm)?
Maretron dedicated (quite expensive!) screens? or what else?

I'm seriously considering building a custom NMEA2K screen where various such data can be presented, but I'd rather skip that for now.
An extra problem I have is that by not "listening" to such sentences, I cannot even setup alarms, not to keen to see the gbox oil pressure as such, but keen to get a beeeeep when it drops low...

cheers

V.

 

[rafiki_]

Sorry Vas, this is all too clever for me. Both JRudge and Mike (Hurricane) are capable of dabbling in this arena, so you might try a PM?

 

[robrennie]

Out of interest, how are you measuring these temperatures and then converting them to digital.

 

[Anders_P42]

If you're in control of creating the NMEA sentences, for the gearbox pressure why not use a scaling factor of divide by 10? It will display 30-36 psi on displays but you can simply multiply by 10.

 

[vas]

Sorry Vas, this is all too clever for me. Both JRudge and Mike (Hurricane) are capable of dabbling in this arena, so you might try a PM?

true P., mainly interested on stirring some discussion on the topic for the ones that DONT have el. engines, iirc both Jeremy and Mike do have el. engines, so they don't count

Out of interest, how are you measuring these temperatures and then converting them to digital.

various sensors (-30-40 up to a few hundred C, or proper K-type thermistors for EGT) that hook up to an arduino board (teensy for size and power), data processed with own libraries and converted to NMEA2000 sentences using Timo's NMEA libraries and a 2euro chip. So sky's the limit so to speak other than Garmin doesn't bother to support the important engine health and safety related sentences (which is dead easy to do hence my questioning!) Feels like they do support ones that they have h/w to document (or some bog standard ones) which is rather poor on their behalf.
I've started a few threads on various data to NMEA2K in PBO (mainly) if you give me some time I'll link to them during the w/e as I'm on the road now.

If you're in control of creating the NMEA sentences, for the gearbox pressure why not use a scaling factor of divide by 10? It will display 30-36 psi on displays but you can simply multiply by 10.

true as you can imagine dead easy to do (although tbh didn't think of it as I want values to be values on the screen!) however doesn't solve the problem with the EGT which is not there and using f.e. baitwell for EGT (again with a factor of ten) is rather silly

So out of curiosity (mind, not going to strip my Garmin kit for another brand any time soon or ever on MiToS), does any other mainstream brand supports such sentences? I'd rather spent money on aft deck canvas this winter rather than a Maretron screen!

cheers

V.

 

[robrennie]

Thanks VAS - good luck with it, love to hear more about how you get on.

Out of interest, when you start looking at displays - you might want to look at Codesys enabled HMI's - they natively take various CanBus networks (and can be modified to take more), and have most graphical elements you would need, together with PLC logic and auto display building.

I used them a lot a few years ago - feel free to PM if you want a geek fest on the subject

 

[vas]

Thanks VAS - good luck with it, love to hear more about how you get on.

Out of interest, when you start looking at displays - you might want to look at Codesys enabled HMI's - they natively take various CanBus networks (and can be modified to take more), and have most graphical elements you would need, together with PLC logic and auto display building.

I used them a lot a few years ago - feel free to PM if you want a geek fest on the subject

you'll definitely hear from me once I find a solution...

What you propose is new to me (unsurprisingly!) but I'm afraid wont be suitable as it's more expensive than the dedicated NMEA2000 Maretron displays and I'll have to write and support both the conversion of data from NMEA2K to whatever this Codesys v3.0 (or 3.5) needs and sort out the graphics visualisation. If it were cheaper would be a nice project for retirement but I'm around 15yrs away and I'm sure they'll have more stuff then to play with (if I can afford them that is...)

I think I'll contact Garmin directly and hope for at least correction on gbox oil pressure range and possibly EGT support at least on their small displays!

cheers

V.