Author Topic: Serial Connection  (Read 460 times)

0 Members and 1 Guest are viewing this topic.

Offline wxnerd

  • Senior Member
  • **
  • Posts: 52
Serial Connection
« on: June 10, 2024, 01:11:21 PM »
Apologies, as I'm sure this has been covered...Yet searching past threads, I'm finding conflicting information and getting more and more confused.

Is it still possible to make a serial connection to a VP2 console using a usb/ttl 3.3v adapter? This worked on my original VP1 station by simply connecting the RX/TX/GND to the proper pins on the Davis console expansion...But with my newer VP2, this does not work. When I try to send commands via a terminal, it only responds "Secured-logger failed"....I've seen some posts here suggesting modern VP2's somehow block this unless using a genuine Davis datalogger, yet I'm still seeing 3rd party dataloggers suggesting it's still possible to bypass any blocks.

Online vinceskahan

  • Senior Contributor
  • ****
  • Posts: 196
    • home site
Re: Serial Connection
« Reply #1 on: June 10, 2024, 02:38:38 PM »
Folks are selling all kinds of loggers like meteopi and wifilogger and the like, so I have to think it's not a problem.

But nowadays I'd probably just do weewx on a pi with the rtldavis driver and a SDR to listen to the ISS directly with a local BME280 for pressure.  Works great.
WeeWX sites:
  Davis VP2+DFARS to a pi4
  EcoWitt GW1000, WH32 outdoor T+H, multiple WH31 indoor T+H, WH51 soilMoisture, WH34 soilTemp (pi4)
  Davis AirLink (inside)
  PurpleAir (outside)
Home site:        https://www.skahan.net/
Wunderground: KWAFEDER15
PWS:                KWFEDER15
CWOP:              CW6881

Offline Garth Bock

  • Table Rock Lake Weather
  • Forecaster
  • *****
  • Posts: 2758
Re: Serial Connection
« Reply #2 on: June 10, 2024, 06:00:08 PM »
The DIY Logger is more cost effective and very compatible. I have tested it with all the Windows based weather software and have had no problems. I tested it with multiple consoles and Envoys with firmware from 1,9 to 3.88. If you decide to get a DIY Logger from Scaled Instruments, I have an extra USB-TTL cable fully tested and plug and go.

There was a posting here in the past (and I think I have it saved somewhere) about direct connection of a console/envoy to a serial port of a computer. The problem with that is (I'm sure you know) there will be no logger so if the computer is shut down or power goes out there will be lost data. Is that what you are wanting to do?

Offline johnd

  • Forecaster
  • *****
  • Posts: 4884
    • www.weatherstations.co.uk
Re: Serial Connection
« Reply #3 on: Yesterday at 05:15:09 AM »
Is it still possible to make a serial connection to a VP2 console using (only) a usb/ttl 3.3v adapter?

In theory yes, in practice probably no. Legacy 6312 VP2 consoles made since about 2012 have some extra proprietary checks that are passed during the initial communication. Unless you can replicate the correct checks in PC software (which are not publicly documented anywhere AFAIK) then communication will fail. This is related to the 'green dot' issue.
Prodata Weather Systems
Prodata's FAQ/support site for Davis stations
Includes many details on 6313 Weatherlink console.
UK Davis Premier Dealer - All Davis stations, accessories and spares
Cambridge UK

Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline wxnerd

  • Senior Member
  • **
  • Posts: 52
Re: Serial Connection
« Reply #4 on: Yesterday at 11:03:43 AM »

There was a posting here in the past (and I think I have it saved somewhere) about direct connection of a console/envoy to a serial port of a computer. The problem with that is (I'm sure you know) there will be no logger so if the computer is shut down or power goes out there will be lost data. Is that what you are wanting to do?

Right, this is what I'm trying to do. At this point, I'm not really looking for any permanent logging. Just doing a temporary experiment comparing 2 wx stations side by side with different radiation shields. I wanted to graph out some data to see how each responds to different wind speeds and such. Only would be using it a couple of hours, so it wouldn't be worth $89...

I could do this with my original VP1 just by connecting 3 wires between the console and a $4 USB TTL adapter. With the new "green dot" units, Davis put in a block to prevent us from connecting to the console this way (They want us to buy their over-priced Weatherlink logger; not use a $4 serial cable)...Obviously, some have figured a way to hack through that block to make these 3rd party loggers, but I can't seem to figure how they did it.

In theory yes, in practice probably no. Legacy 6312 VP2 consoles made since about 2012 have some extra proprietary checks that are passed during the initial communication. Unless you can replicate the correct checks in PC software (which are not publicly documented anywhere AFAIK) then communication will fail. This is related to the 'green dot' issue.

Guessing none of the free softwares out there (Cumulus, Weewx, etc.) have the ability to replicate those checks?

Online vinceskahan

  • Senior Contributor
  • ****
  • Posts: 196
    • home site
Re: Serial Connection
« Reply #5 on: Yesterday at 01:26:42 PM »
Geez Davis wants 229 for the loggers now ?  Bandits !!!!!    Even at 165 at scaledinstruments that is a crazy price.

(I paid $119 in early 2009 for my Davis serial logger)

You could do two weewx+rtldavis rtlsdr antenna setups for under 100 if you have a couple raspi around unused.   Publish/subscribe the data via MQTT.  Weewx can do the graphing nicely.   I have a 2020 version of https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0CD7558GT if that helps any.

But yes it would be nice to find a way to just cobble a cable together.  I did a quick search on the weewx google group but didn't find anybody who'd done so.  Most people just spend the money for a wifilogger or meteopi if they don't go Davis.
WeeWX sites:
  Davis VP2+DFARS to a pi4
  EcoWitt GW1000, WH32 outdoor T+H, multiple WH31 indoor T+H, WH51 soilMoisture, WH34 soilTemp (pi4)
  Davis AirLink (inside)
  PurpleAir (outside)
Home site:        https://www.skahan.net/
Wunderground: KWAFEDER15
PWS:                KWFEDER15
CWOP:              CW6881

Offline Garth Bock

  • Table Rock Lake Weather
  • Forecaster
  • *****
  • Posts: 2758
Re: Serial Connection
« Reply #6 on: Yesterday at 01:39:12 PM »
The DIYLogger is the most cost effective and easiest way right now. For about $100 you get a compatible logger that works with any of the current weather programs. You don't need to cobble together multiple components, just plug and play. Also you can use it with an SBC for specialized applications. The only thing you need to purchase is a USB -TTL cable from Amazonia or a slow boat from Alibaba or Temu. I will be keeping extras on hand in case anyone needs one pre-setupped and tested.

https://www.scaledinstruments.com/shop/shop-by-category/data-loggers/diy-logger-for-davis-pro2-and-vue/

Offline 92merc

  • BismarckWeather.net
  • Forecaster
  • *****
  • Posts: 1332
  • BismarckWeather.net
    • BismarckWeather.net
Re: Serial Connection
« Reply #7 on: Yesterday at 02:22:21 PM »
I am running 2 Belfryboy loggers.  Even cheaper than the DIY.

http://belfryboyweatherbits.blogspot.com/p/the-belfryboy-clone-usb-logger.html
https://www.BismarckWeather.net
Davis VP2, Cumulus, WeatherDisplay, Blitzortung, Saratoga Scripts, NOAA Stream via PI

Offline Garth Bock

  • Table Rock Lake Weather
  • Forecaster
  • *****
  • Posts: 2758
Re: Serial Connection
« Reply #8 on: Yesterday at 08:32:29 PM »
I am running 2 Belfryboy loggers.  Even cheaper than the DIY.

http://belfryboyweatherbits.blogspot.com/p/the-belfryboy-clone-usb-logger.html

I would have mentioned his too but there hasn't been a posting about his logger in quite a while. I wasn't sure if he was still making and selling them. One thing not mentioned is if his logger works with VVPro or Weatherlink.
« Last Edit: Yesterday at 08:35:05 PM by Garth Bock »

Offline 92merc

  • BismarckWeather.net
  • Forecaster
  • *****
  • Posts: 1332
  • BismarckWeather.net
    • BismarckWeather.net
Re: Serial Connection
« Reply #9 on: Yesterday at 08:42:49 PM »
It should work the same as the Davis unit.  What I wasn't sure about the DIY unit is if it has a memory logger like the OEM Davis.  The Belfryboy logger does have memory in it.

I had it working on VVP and Cumulus at one time.  I now have it on Cumulus and Weather Display directly with 2 consoles and loggers.
https://www.BismarckWeather.net
Davis VP2, Cumulus, WeatherDisplay, Blitzortung, Saratoga Scripts, NOAA Stream via PI

Offline Garth Bock

  • Table Rock Lake Weather
  • Forecaster
  • *****
  • Posts: 2758
Re: Serial Connection
« Reply #10 on: Yesterday at 09:13:41 PM »
The DIYLogger has a memory. Basically it has the same build as a WifiLogger but has a serial port. The nice thing is that it is flexible in that you can connect it to a SBC directly or to a specialized controller for other designs. This is just one step above a basic logger with its open framework.

Offline johnd

  • Forecaster
  • *****
  • Posts: 4884
    • www.weatherstations.co.uk
Re: Serial Connection
« Reply #11 on: Today at 07:13:33 AM »
Guessing none of the free softwares out there (Cumulus, Weewx, etc.) have the ability to replicate those checks?

Not so far as I know. It is usually never needed in software because whichever computer you're using to run the software typically interfaces to a logger rather than direct to a console. And it's the logger that handles the 'green dot' check. So adding the check to software would typically be pointless.
Prodata Weather Systems
Prodata's FAQ/support site for Davis stations
Includes many details on 6313 Weatherlink console.
UK Davis Premier Dealer - All Davis stations, accessories and spares
Cambridge UK

Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.