LoraWAN weather station

I’ve just received a nice new ‘headless’ weather station from China, and are engaged in connecting to its RS485 feed and understanding the protocol. They supplied a RS485-UART USB stick with it, and after playing around with some containerised NodeRED flows which couldn’t read the USB finally just used PySerial and have started dumping the data. Although it is advertised with the tag line “we will supply the communications protocol” this wasn’t forthcoming so I just dumped the bits down on the screen and have started reading them. Apparently they are a Fine Offset type of station and equivalent to the WH2950 type, without the monitor or network link. It’s all down to me!

The bytes look like this:

24 B3 7A 62 61 46 00 00 00 00 00 01 00 00 00 48 A3 $.zbaF………H.
24 B3 7A 62 61 46 00 00 00 00 00 00 00 00 00 D3 2D $.zbaF……….-
24 B3 7A 62 61 46 00 00 00 00 00 02 00 00 00 D4 30 $.zbaF……….0
24 B3 7A 62 61 46 00 00 00 00 00 00 00 00 00 D3 2D $.zbaF……….-

… which is fun. I quickly worked out that the standard size was 17 bytes, now I have run it through a hex dumper and started eye-balling the bytes. I may need to spin the anemometer to generate events to get readings, but this looks good.

Later, my aim is to terminate this with a Lora-capable low-power chip and send it down the back garden to my shed roof, where it will transmit to my loft Lora receiver and hence to my data logging, but for now I am happy to have it perched on my desk and playing with bytes.


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