Author Topic: Direct connection to wired Davis ISS  (Read 2023 times)

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Offline dwall

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Direct connection to wired Davis ISS
« on: August 21, 2017, 10:44:24 AM »
I recently had the requirement to interface a Davis weather station ISS directly to an Arduino without the the Vantage Pro 2 console (this was an remote data logging station where weather was only one of many things being measured and the display was not needed or wanted).  As discovered by others on this forum, the console output from the ISS is RS422/485 at 4800 baud 8/N/1.  I was able to use an RS485 Arduino shield board (https://www.sparkfun.com/products/12965) to make this signal readable by the Arduino (a Raspberry Pi RS485 board is also available by the way).  I used an RJ11 Socket (https://www.digikey.ca/product-detail/en/hirose-electric-co-ltd/TM1RV-623K66-35S-150M/H11393-ND/1136170) to access the signals (be careful, the wire colors are reversed from the ISS cable). 

As a result, I could read the data packets coming from the ISS.  They are 6-byte packets that are virtually identical to the 8-byte messages from the STRMON command (https://github.com/dekay/DavisRFM69/wiki/Message-Protocol) except for the lack of the 2-byte checksum.  The attached Arduino code is capable of decoding wind speed, direction, temperature, humidity, rain, rain rate and gust values.  Feel free to use it or modify as required.

Offline Bushman

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Re: Direct connection to wired Davis ISS
« Reply #1 on: August 21, 2017, 11:03:49 AM »
IMPRESSIVE!!!!!  =D>  The idea of a Pi Zero W with RS485 would allow a console to become wireless. (And offer BT connection as well in a package not much larger than the current Davis logger).  Thanks for sharing.
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Offline mutton

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Re: Direct connection to wired Davis ISS
« Reply #2 on: April 08, 2019, 10:09:28 PM »
Sorry to resurrect an old topic, but I just got this working using your code - thanks!

What I am wondering is can you force a reset of the rainfall by sending a message through the serial connection - or even just reset the board with a command?

cheers
Paul

Offline davidmc36

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Re: Direct connection to wired Davis ISS
« Reply #3 on: April 09, 2019, 07:41:56 AM »
Glad to see this pop up. Could be a good solution for Radio Control Model Plane field. No power there so this would be light demand on solar. Pi Zero and a Cell Modem.......hmmmmmm

Offline mutton

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Re: Direct connection to wired Davis ISS
« Reply #4 on: April 09, 2019, 07:49:59 AM »
I have it connected to an arduino using LoRaWAN sending the data 25 miles.

I bought a cabled sensor suite (the spare parts kit) and have hooked everything up and got it working ok, just can't reset the rain, which must come from the console?

or does it have an onboard RTC which I cannot see.

cheers
Paul

Offline davidmc36

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Re: Direct connection to wired Davis ISS
« Reply #5 on: April 09, 2019, 08:14:07 AM »
LoRa, interesting. should be flat enough between me and the field. Especially if I use top of circus tent at the field and my 35 foot tower at home. Only about 20 clicks.

Offline mcrossley

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Re: Direct connection to wired Davis ISS
« Reply #6 on: April 09, 2019, 08:40:37 AM »
I have it connected to an arduino using LoRaWAN sending the data 25 miles.

I bought a cabled sensor suite (the spare parts kit) and have hooked everything up and got it working ok, just can't reset the rain, which must come from the console?

or does it have an onboard RTC which I cannot see.

cheers
Paul
Rainfall is sorted out in the console -hour,day, month, year
Mark

Offline mutton

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Re: Direct connection to wired Davis ISS
« Reply #7 on: April 09, 2019, 08:51:18 AM »
so i am wondering how the console resets the rain total that is getting sent by the ISS (I think at 12am)

or the console just deals with the maths and the ISS board just keeps counting

Offline johnd

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Re: Direct connection to wired Davis ISS
« Reply #8 on: April 09, 2019, 08:52:54 AM »
or the console just deals with the maths and the ISS board just keeps counting

Correct. There is never any communication back to the ISS.
Prodata Weather Systems
Prodata's dedicated Davis EnviroMonitor website
UK Davis Premier Dealer - All Davis stations, accessories and spares
Littleport, Ely, Cambs UK

Offline kobuki

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Re: Direct connection to wired Davis ISS
« Reply #9 on: April 09, 2019, 05:32:41 PM »
I have it connected to an arduino using LoRaWAN sending the data 25 miles.

That's pretty damn impressive. Could you tell what module and MCU you used?

Offline mutton

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Re: Direct connection to wired Davis ISS
« Reply #10 on: April 11, 2019, 08:39:02 PM »
I'm using a Sodaq Explorer https://support.sodaq.com/sodaq-one/explorer/ because its layout matched the Zero/Uno layout for the shield but I have also just used some jumper wires from the shield to a TTGo Lora32 https://github.com/LilyGO/TTGO-LORA32-V2.0 as well using the RX/TX pins. The data gets sent through The Things Network.

Both work well - just have to either use nodeRED, InfluxDb and or Grafana to display the figures correctly (my SQL skills aren't what they used to be and maths hurts my head most days)

Offline kobuki

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Re: Direct connection to wired Davis ISS
« Reply #11 on: April 12, 2019, 05:18:31 AM »
I see, nice. Does using TTN mean your packets are relayed through several nodes and you're just transmitting to the nearest one, and not the full 25 miles?

Offline mutton

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Re: Direct connection to wired Davis ISS
« Reply #12 on: April 12, 2019, 06:54:55 AM »
No it operates on one central gateway that has an internet connection - I help farmers put them on their farms.

Range is dependant on a lot of stuff but height of the gateway antenna is a major factor.

Weather stations are just a small part of it - we do water tank levels, cattle trough levels, electric fence monitors, gate monitors and even feral pig trap monitors.

cheers
Paul

Offline kobuki

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Re: Direct connection to wired Davis ISS
« Reply #13 on: April 12, 2019, 07:13:50 AM »
I see. Sorry for the nitpicking, but TTN is a network of gateway nodes and clients that connect to those gateways. How I see it is you have your own gateway connected to TTN and steer your TTN-registered client nodes (if that's possible) to use that. Is that correct? So far I have only an overall understanding of their free network.

Offline mutton

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Re: Direct connection to wired Davis ISS
« Reply #14 on: April 12, 2019, 10:07:21 PM »
TTN is a community of people who build, own and deploy gateways themselves and join them to TTN servers for all to use.

Physically there is the node (up to 10,000 for each gateway) and gateway which has as internet connection sending the packets received from the nodes to TTN.  TTN handles the security, applications (where the data goes) and forwarding onto other cloud applications through inbuilt integrations.

One node (end device with sensors like a weather station) could use several gateways if they are in range, so the same packet of info could come in to TTN 2 or 3 times, but is deduplicated at the application server.

Gateways setup to use TTN are open for public use, and there are fair use policies in place.

Hope that answers some questions, keep asking or go and check out TTN if you have more

cheers
Paul

Offline kobuki

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Re: Direct connection to wired Davis ISS
« Reply #15 on: April 13, 2019, 05:00:03 AM »
No, that's plenty of info, thanks. I guess your nearest GW is about 25 miles away, then. I didn't know it uses a broadcasting system without negotiating the nearest gateway, that's new to me. Not very effective, but maybe a bit more robust and a lot simpler.