Vegetronix Soil moisture sensore, half readings

[mariusmartocsan]

Hello.
I have 8 sensors like this: https://www.vegetronix.com/Products/VH400/
4 connected to an ai extension and 4 connected to Loxone miniserver AI readings on ports 1,2, 4,5.
I have a separate 12V source that is conected with GND from sensor and GND goes back to AI extension and Lxoone miniserver.
If i read with multimeter i get the right readings, when i conect to miniserver or AI,I get 50% reding, like i hould have 3 volts with loxone i get 1,48 for example.

Any ideea why i get only half of the value?? compared with a multimeter reading before inserting in loxone?

[hme0354]

Have you connected the 12v gnd to the miniserver gnd?

[mariusmartocsan]

YES.
Also have one whure to GND from port 3 of AI ports from miniserver gen 1, with no difference in readings. They are half. Could be because multiple sources like 24V and 12 V are used?

[Prof.Mobilux]

This is behause of the Input resistors Loxone uses for the AI. See also here (german, please use Google translate): http://hums-baublog.blogspot.com/201...it-loxone.html

so no error - its normal to have 1.48V Max.

[mariusmartocsan]

Thank you for your reply and link.
ANY one here who burried the vegetronix? Mine is at 20-25 cm deep under the grass and soil is a little clay, i aleays have 97-98% considering 1.48 as 100%. Even after one week of sun and at top the soil is visible dry and cracked, at top i have 10-15 cm of sandy soil. Any advice? Anyone has a tutorial or picture how they burried their vegetronix. Cant find anywhere a tutorial not wvwn vegetronix website or manual.

[Prof.Mobilux]

Yes, I think it is too deep. I have it just under ground level (so the head is just under ground, but maybe only 1-2 cm) and NOT on grass but installed in a flower bed. And I installed it at 45° so that it faster show that moisture is gone.

Remember that grass really good protects the ground from evaporation. So it is no wonder that you have really a high moisture in 25-30 cm depth.

I would recommend to install it not in grass but in "normal" unprotected ground and install it right under ground level. Next problem is that there will be capillaries after some time in the ground, which let you have always a very high moisture. So you have to pull the sensor from time to time and destroy the capillaries in the ground.

[mariusmartocsan]

Thanks for the advices, to bad that i did not find more info about this and i hope other will came across this topic. Now will be hard to do that as i have to try to find where i put the senor, i know only on a 1m radius , will be fun to find a method to detect them.

So i have 5 sensors where i have shyrubs and small plants, there will be more easy to pull on top of the ground and insert them like you say, at 45 degree and will enter only as much as the blade is, will be easy to pull off and clean each time is necesary.

The problem is the grass as there i need to think to a solution, one will be to use some kind of irrigation box, and drill a hole, and then will be easy to access and clean or any other task, the problem is the sensor is in the middle of the area. Second option will be to urry at 10-12 cm from the top, but again will be hard to have access to it and clean it, any other ideas?

Did you put in the Loxone as 1.48V being 100% moisture and 0.1V as 0%? Or which values did you use? Also at wich value should we considered irrigating? Like when it drops to x%? OR how do you calibrate the amount of water and when to do it?

Any advice is welcome. Thanks again for anyone here for help.

[Prof.Mobilux]

Well, to be honest I do not use the sensor anymore to calculate when or how much irrigation is needed. It was quite to uncertain... No one can say that you have to start irrigation at a certain sensor level. You have to try by your own. I just checked the moisture at different level of the sensor and decided by my own when it is time to irrigate.

Nowadays, I use Evapotranspiration to calculate the amount of needed irrigation: https://www.loxwiki.eu/pages/viewpag...ageId=70353372

Attached are the settings of my sensor:

[Gast]

I found good documentation. Thanks for the reply and the link.
happy wheels