I broght a Soil-Multi-Parameter Sensor frome Aliexpress:
Aliexpress Sensor
This sensor have a Serial URAT connection via RS485.
Have some one may be already expirience with this kind of Sensor?
Or with implemanting RX and RS485 and seperating the Sensor data to each of Home assist Sensor.
Thanx for any Help
Many of the sensor values are pretty much useless.
Temperature and humidity/moisture are okay, but all the other values are linked to humidity/moisture and each other, which means you need to figure out every combination to be able to use it.
Normally it is only moisture/humidity and nutrients that are measured, but even that it pretty much impossible to map out and without that mapping you can’t see anything from the values.
When the moisture in a lump of dirt drops, then the nutrients will too, because the nutrients is dissolved in the water, so when the water disappear, then the nutrients gets stuck and become unavailable.
That means in order to use the value, then you need to determine of much a change in nutrients come from a change humidity and how much come from a direct change to the amount of nutrients in the dirt.
As far as I know none of these curves have a straight forward formula, so you need to gather LOTS of data points to make an assumption.
You have the nutrients split out too, so you need to multiple this gathering of data points with each of your extra measuring values.
But ignoring the diminishing value of the extra sensor points, then the type of sensor being resistive also means that there is a direct contact to dirt from the electrical parts and that means the sensor will slowly erode itself and might also pollute the dirt.
I don’t know which model you have, but if you expect to get real NPK data out of it, just leave it alone. It’s just simply impossible.
If you want to experiment with cinese modbus protocols for learning purposes, then it’s ok. We have done many on Arduino forum.
ps. this photo from user manual tells what to do with your sensor
R.I.P.