Barometer History Dashboard Display

[caleroific]

There seems to be a glitch in the time coordinate for this display - see attached.

I am running OpenCPN v 4.8.4 in Windows 10

Any chance of a quick fix?

Thank you

[transmitterdan]

It looks like the glitch is in the sensor data. The time axis for dashboard graphs contains one point for each sensor reading. It appears that every so often the number of sensor readings are reduced for some reason. For this graph to work the sensor readings need to be regularly spaced in time.

[caleroific]

Hi Dan

I don't understand! My sensor is sending a reading approximately every 10 seconds. The reading contains no time stamp just a temperature and pressure. The plot on the the timeline looks good. It's the background graphics which are confused.

Surely the coordinates and associated graphics are generated by OpenCPN according to the clock even if no data is received. Is this the PC clock or the GPS clock? Either way it is independent of the data being collected and in my opinion a display issue.

[transmitterdan]

Originally Posted by caleroific

Hi Dan

I don't understand! My sensor is sending a reading approximately every 10 seconds. The reading contains no time stamp just a temperature and pressure. The plot on the the timeline looks good. It's the background graphics which are confused.

Surely the coordinates and associated graphics are generated by OpenCPN according to the clock even if no data is received. Is this the PC clock or the GPS clock? Either way it is independent of the data being collected and in my opinion a display issue.

Please don't be mad at anyone. We are just trying to help. Most dashboard instruments get updated from 1 to 10 times per second. So getting an update once very 10 seconds may be the issue.

The data is plotted as a line drawn as a series of equal length segments. I believe there are 3,000 sensor readings on the graph. I have to check the source code to be sure. So if the sensor sends 1 reading every 10 seconds and it takes 3,000 readings to complete the graph it means 30,000 seconds of data or about 8 hours. If no pressure data is received the chart does not get updated.

The chart object tries to draw a vertical bar every 5 or 15 minutes of the CPU clock. Again, I have to check the source code to be sure about that because it is hard coded. So it's trying to draw lots of vertical bars and they overlap and get mangled. Sometimes they look right and sometimes they look stupid.

I think you could ask via the feature tracker at opencpn.org if the history plot could be made user selectable for the time between vertical bars. For you it should probably be something like 2 hours not 15 minutes.

An alternative would be to make the barometer history plot a fixed number of samples (say 1,000) between the vertical time bars. That might be more in tune with what the majority of users expect.

[caleroific]

Sorry if you think I am mad about this. I love OpenCPN and use it primarily for passage planning and management of AIS targets. I have donated to the project.

I am playing with the Nanobaro NMEA Barometer to evaluate it for use on my boat. Ref:

https://sdfjkl.org/blog/2017-08-09-nanobaro/

Thank you for your explanation. I don't wish to speed up my source data because it will reduce the 8 hour display. Ideally I was looking for at least 24 hours.

For now I am happy to live with the constraints and will raise a change request if/when I wish to take this further.

Thank you

[Baikal]

Is there any movement in the direction of setting the time interval for reading the history of the barometer?

I would like to be able to customize the display of the history of the barometer with a given value per minute, hour, days

[seandepagnier]

Originally Posted by caleroific

Sorr
Thank you for your explanation. I don't wish to speed up my source data because it will reduce the 8 hour display. Ideally I was looking for at least 24 hours.

For now I am happy to live with the constraints and will raise a change request if/when I wish to take this further.

Thank you

Did you try the plots plugin? It can plot barometer too, and it's possible to change the time scale to many values from 5 minutes to 60 days. My barometer is 1 reading per second, but the rate does not matter.

[Baikal]

Originally Posted by boat_alexandra

Did you try the plots plugin? It can plot barometer too, and it's possible to change the time scale to many values from 5 minutes to 60 days. My barometer is 1 reading per second, but the rate does not matter.

Sean, everything works well in your plugin! I would like the same thing in setting the display in time but for the dashboard. At least the basic functionality!