EngineDashboard Data refresh rate?

[Andreas29]

Hi,

when using the plugin Engine_dashbord it´s possible to show tank levels with incoming NMEA-XDR-Sentences.
I use the network broadcast adress to get the NMEA-packages.
This works but there´s one point I think about.

When the data transmitting rate is lower then one Sentence every 5 sec. then the instrument falls to zero until the new sentence comes in.

So when I send e.g. every 10 sec. one Datapackage with 50% level the instrument shows 50% then falls to zero then 50% and so on.

A refreshing rate every 5 sec for tank levels seems very short. Is there a possiblity to get a refreshing rate round about once per minute or so?

Thanks and regards

Andreas

[Hakan]

Andreas..
I haven't been involved at all in the EngineDashboard but a watchdog set to six seconds is normally used in OpenCPN Dashboard and probably copied from there.
There are also a new prolonged watchdog for some SignalK data set to 30 seconds.


But what's the problem for you to send every four or five seconds if the plugin want it like that?

[Andreas29]

Hi,

@Hakan: Thanks for your information.

There´s no big problem.
But more NMEA-Sentences per second = more traffic in the network and -and this is the more interesting point- I use a Wemos D1 pro mini as transducer and when I send less datapackets via the WiFi the power consumption will be more less.
At the end -if thinks work as I think- I´ll use three or some more of them and each uses ca. 70mA (and in sending burst up to 200 mA). It´s possible to bring the Wifimodem into a sleep mode then the module needs round 16 mA.

So sending once per minute just reduces the power consumption.

Regards

Andreas

[Hakan]

OK, so then you'll have to convince the plugin maker to change the watchdog. Or rebuild it yourself? I can agree a fuel level would not need a short WD.

[Andreas29]

Hi,

in the code in the EngineDashboard/src/dashboard_pi.cpp in Line 393 stands:
if (wxDateTime::Now() > (watchDogTime + wxTimeSpan::Seconds(5))) {

and this is -when I understand the comments in the code- the watchdog function. So changing the 5 to 50 or 60 and then the watchdog waits long enough. I must try this in the next days and rebuild the plugin.

Regards

Andreas

[Hakan]

Andreas..
This is not built as the O-Dashboard where all instruments have it's own watchdog. So yes I agree although I'm not a code master. Make a try but I think it will affect all instruments. Also the RPM meter and a strange effect when you switch the motor off. So nothing to spread around.

[stevead]

The instruments are updated on receipt of the respective NMEA 183 sentence keeping in mind whatever latency is incurred during processing.

So for example if your Rudder Angle sensor transmits NMEA 183 sentences at a rate of 1 Hz, the engine dashboard rudder angle gauge will be updated at the same frequency.

If the engine has a NMEA 2000 interface and transmits RPM, Oil Pressure and Water Temperature at a rate of 10Hz, the TwoCan Plugin (another plugin that allows OpenCPN to use NMEA 2000 data), will convert these NMEA 2000 messages to NMEA 183 sentences which in turn will be received by OpenCPN and forwarded to the Engine Dashboard plugin, again at the same frequency but with some latency incurred.

The role of the watch dog timer is to simply zero the instruments if no sentence has been received with 5 seconds. Just like when you turn off the ignition, the fuel tank, oil pressure, water temp gauges etc. return to zero. I'll readily admit that this is a crude/simplistic mechanism and could possibly be improved by having individually configured watch dog timers for each gauge, but as the old saying goes, "you can put lipstick on a pig....". Plus there are other things I would prefer to spend my time on.

In your particular case where you are developing your own sensors using the Wemos D1 interface, its entirely up to you as to what rate you want to send data. Just keep in mind that if you choose a rate slower than 0.2 Hz (once per 5 seconds) the watchdog timer, as it is currently configured will cause the Engine Dashboard to zero its gauges until it receives new values.

[Andreas29]

Hi,

@Hakan: I agree. This was more a first quick´n dirty solution and like you I´m not a code master

@stevead: Yes, time is one of he greatest treasures we have (or not)
I saw the code lines and you confirm my guess.
I agree with you, this is a simplistic method to set the gauges to zero if the engine´s shut off.

During my Tests I just send one nmea-XDR-Datastream to OC.
This special XDR-Tank-Level Data and no other nmea-data.

Look this watchdog only for the engine NMEA-Sentences or watch it generally for nmea-Sentences?
Later in the real boat-network there are much more Data-streams transmitting to oc and if this watchdog looks for all sentences I don´t have to send the tank-Level-Data every 5 seconds.
An other possiility is to use the nmea-converter Plugin to send a fake engine-nmea-data-stream so that the watchdog think all is fine

Thank you @stevead for your work and for developing this plugin.

Regards

Andreas

[stevead]

It would actually help if I looked at the code, which I've just done now whilst finalising the changes to support the new OpenCPN v5.2 Plugin Manager and issuing the PR for the metadata xml files.

The instruments are updated on receipt of the respective NMEA 183 sentence keeping in mind whatever latency is incurred during processing.

While the instrument values are updated on receipt of the respective sentence, the instruments are only repainted on the screen every second. (This occurs in the same wxTimer loop in which the watchdog value is checked)

Note that the use of a watch dog timer in the Engine Dashboard is independent and distinct to watch dog timers used elsewhere in OpenCPN and in other plugins. If the Engine Dashboard sets a watch dog timer of 5 seconds it has no effect on other components in the system. For me it is just a simple way to zero an instrument if it no longer receives valid data.

Unfortunately I don't have any NMEA 2000 or NMEA 183 sensors on my engine, so I have no idea what data if any is transmitted by an engine oil pressure sensor or tachometer once the engine has been turned off, even though the sensor itself may be powered independently from the engine, for example it may be powered by the NMEA 2000 bus. So I thought it would just be easier to use a watchdog timer to zero an instrument if it stopped receiving data.

If your major concern is network utilisation (and I'm assuming your talking about your WiFi network connecting OpenCPN to your sensor devices), then a tank level sensor transmitting one NMEA 183 sentence every second is hardly going to be noticeable, let alone affect the power consumption of your Wemos D1 interface.

It would be nice to have an individual watch dog timer for each gauge, or at least high (10Hz) & low speed (1Hz) timers, but this is not a high priority for me at the moment.

[Andreas29]

Hi,

@stevead: Thanks for your explanation. I agree with you, the solution for zeroing the ínstruments will be very easy and I would have done it that way too.

The question now is if the watchdog in the plugin just watch for the specific nmea-sentences used in the enine dashbord plugin or will accept any nmea-sentence send to OC.

You´re right when you say one wemos is hardly going to be noticeable.
But if I use three (ore more) of them then the difference will be > 3,6 Ah / 24h. So when energy is a point to look for then it´s better to try to reduce the power consumption .

Regards

Andreas

[Andreas29]

Hi,

got an easy "workaround"

With the NMEA-Converter-plugin it´s possible to send virtual NMEA-sentences. When I let send a XDR-NMEA Sentence e.g. Oil-Pressure for the port engine and let do the plugin this every second then I can send the xdr-NMEA-tank-level sentences in a longer interval.
The watchdog noticed the (fake) NMEA-sentence as a real one and don´t set the instruments to zero.
The disadvantage is that the instruments don´t fall to zero if the transducer stops to transmit but this is something I can live with and therefore I can use the watchdogplugin to observe if the tank-level-transducer transmitting data.

Regards

Andreas

[stevead]

The question now is if the watchdog in the plugin just watch for the specific nmea-sentences used in the engine dashboard plugin or will accept any nmea-sentence send to OC.

The Engine Dashboard plugin returns the flag WANTS_NMEA_SENTENCES when it is initialised, and the plugin's SetNMEASentence method is invoked for every NMEA 183 sentence that OpenCPN receives.

That method performs a basic inspection of the sentence to obtain the mnemonic but will only parse RPM, RSA and XDR sentences. The watchdog is only set when valid data is received for one of these sentences. The plugin does not process nor set the watchdog for any other NMEA 183 sentence.

It would be nice if OpenCPN performed the filtering of NMEA 183 sentences but c'est la vie.

[Hakan]

Originally Posted by stevead

It would be nice if OpenCPN performed the filtering of NMEA 183 sentences but c'est la vie.

Well every NMEA0183 passing the multplexer can be filtered but I may misunderstand what you're looking for?

[Andreas29]

Hi,

I made this:

Create a XDR-engine-Sentence in the NMEA-Converter-plugin witch I don´t need to visualize with the engine dashboard.
Let the Nmea-converter-plugin send it every 3 sec.
With my Wemos I can now send the real to show xdr-tank-level sentence in a longer and free-of-choice interval.
To see if the wemos transducer is still alive I send also a control-nmea-sentence with the tank-level-sentence (Talker ID AA) witch I can let control from the watchdog-plugin. So when the transducer transmitting interval is e.g. 30 sec I let the watchdog control the NMEA-Data-stream of Talker ID AA for once every 45 to 60 sec.
Works
The tanklevelinstruments were now not set to zero cause the watchdog of the engine-plugin think every thing is fine due to the virtual input.

Regards

Andreas

[Hakan]

Andreas..
Nice innovative solution to satisfy your needs.