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Communication Protocol

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Vathek
Posts: 30
Joined: Tue 28 Dec 2010 12:16 pm
Weather Station: PCE FWS-20 = Fine Offset WS1080
Operating System: Windows 10 x64
Location: Italy, Mondo Nuovo

Communication Protocol

Post by Vathek »

Hi to everyone, does anyone can tell me how Cumulus interfaces with the la crosse station?

Perhaps it uses the open2300 protocol? If so, where can I find information about it?
Thank you!
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steve
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Re: Communication Protocol

Post by steve »

Cumulus reads the data from station by reading the appropriate memory locations. There's no 'protocol' as such, it's just a case of knowing where in memory each item is, and what its format is, and reading that location. I used the information from the Open2300 web site to write the La Crosse support in Cumulus: http://www.lavrsen.dk/foswiki/bin/view/Open2300/WebHome
Steve
Vathek
Posts: 30
Joined: Tue 28 Dec 2010 12:16 pm
Weather Station: PCE FWS-20 = Fine Offset WS1080
Operating System: Windows 10 x64
Location: Italy, Mondo Nuovo

Re: Communication Protocol

Post by Vathek »

It sounds very interesting because I'm thinking about a kind of "memory expansion" for the lacrosse ws23xx.

As probably you already knows, the station stores in its own memory only 175 set of data.
With cable connected sensors the acquisition happens every 8 sec, in wireless mode instead it happens every 32 sec (wind > 36 km/) or 128 sec (wind < 36 km/h)

So the internal memory is limited to 175*8s = 23 minutes (wired) or 175*32s = 93 minutes (wireless wind>36km/h) or 175*128s = 6,22 hours (wireless wind<36km/h)

When PC is off, station collects data until the buffer is full, and I think that then it erases the old measures to insert new measurements (with a circular buffer memory of 175 last measurements)

If I build "something" that can interface between weather station and PC, and keep memory of old data, perhaps I could let the pc off for more than the original time buffer of the lacrosse. (During heavy storm or long holidays I shut down my pc for more than 6 hours and so I lose data)

I'm thinking about a simple electronic board with a backup memory using PIC microcontroller and an eeprom or SD card...
It will be a very long time term project since my spare time is not much but maybe it could be interesting...
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steve
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Joined: Mon 02 Jun 2008 6:49 pm
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Re: Communication Protocol

Post by steve »

Vathek wrote:As probably you already knows, the station stores in its own memory only 175 set of data.
With cable connected sensors the acquisition happens every 8 sec, in wireless mode instead it happens every 32 sec (wind > 36 km/) or 128 sec (wind < 36 km/h)

So the internal memory is limited to 175*8s = 23 minutes (wired) or 175*32s = 93 minutes (wireless wind>36km/h) or 175*128s = 6,22 hours (wireless wind<36km/h)
The logging interval isn't related to the data acquisition interval, it is configured independently and can be set to between 1 minute (which would give just under three hours capacity) and (I think) 60 hours, which would give about 14 months capacity (but I can't think of any practical use for a logging interval of 60 hours!).

I would guess that most people would use an interval of between 5 and 15 minutes, which gives a capacity of between approx 14.5 hours and approx 44 hours.
Steve
Vathek
Posts: 30
Joined: Tue 28 Dec 2010 12:16 pm
Weather Station: PCE FWS-20 = Fine Offset WS1080
Operating System: Windows 10 x64
Location: Italy, Mondo Nuovo

Re: Communication Protocol

Post by Vathek »

steve wrote: The logging interval isn't related to the data acquisition interval, it is configured independently and can be set to between 1 minute (which would give just under three hours capacity) and (I think) 60 hours, which would give about 14 months capacity (but I can't think of any practical use for a logging interval of 60 hours!).
Ok, I didn't know that, but when you say "Logging interval at 15 min" you mean that weather station can collect data acquisitions for 15 minutes and then read all of them or simply cumulus get the last single data acqusition every 15 minutes?
(The resolution between the two ways is quite different, my idea is to preserve maximum data resolution keeping time memory big)
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steve
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Posts: 26702
Joined: Mon 02 Jun 2008 6:49 pm
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Re: Communication Protocol

Post by steve »

Vathek wrote:Ok, I didn't know that, but when you say "Logging interval at 15 min" you mean that weather station can collect data acquisitions for 15 minutes and then read all of them or simply cumulus get the last single data acqusition every 15 minutes?
(The resolution between the two ways is quite different, my idea is to preserve maximum data resolution keeping time memory big)
I mean that the console is continuously reading data from the sensors, but only creates a logger entry at the interval that you configure. Not every reading is captured to the logger.
Steve
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