Hello,

I'm new to the LOGO Systems and designed my home installation with 3 LOGO 0BA8 24V.

For the moment I'm totally satisfied

But there is something that I'd like to have, it's the monitoring of my LPG Tank.

My gas provider gave me a remote sensor, wich is connected by a 3 wires cable to a little reader with a screen with 4 AAA batteries, which display the level of the tank in %

After after some analyses, this is a "hall effect" gauge wich seems to be the Rochester R3D gauge

My goal would be to keep the provider's display and in parallel, have the information on my logo.

The provider's screen box send every 1 minute the voltage (6V) to the gauge (+ - wires) and the gauge responses for something like 0,5s the

Here is the explanations of this "return signal" from the Rochester R3D datasheet:

Output Voltage
Ratiometric 5-80% of input voltage @ 5-80% volume.

My idea is to use 2 AI of the logo: one with the original voltage and a second with the return voltage, and finally the tank level in a analog memento.

But there is two problems:

- The return signal is "active" 1 time per minute (as I said something like 0,5s)

- I don't have any idea how to treat and compare these 2 AI and make the ratio... For the moment I only worked with digital input & output on my Logo.

And for information, I connected all my 3 LOGO setup to HomeBridge (modbus communication) which make all my Logo setup "Apple HomeKit" compliant.. You understand, the goal would be to have my LPG Tank level in a HomeKit object... :-) 

I hope some of you could help me in this project, which maybe will interrest others too ! :-)

The only thing is parallel is the return signal, which is present only for 0,5s per minute because the gauge is powered only 0,5s per minute by the provider's screen

And in place of the batteries I tried to power the provider's screen with a 5V supply, to have something "more constant" and don't have to replace batteries, it's ok too. So I can have the "original" gauge power voltage on a other AI, this one would be permanent.

Hi there,

That is exactly what is a part of my next extension of my home project.

i have a  diesel tank and two LPG tanks, (i am off grid), The LPG tanks are for heating and cooking.

The 2 tanks are a 40 Meters from my house close to my diesel tank and generator, so inspection from within the house will be nice. I was already checking what type of sensor i can use and you have given a nice idea. At the generator i already use a LOGO PLC networked to the house.

I include the data sheet for what i understood is your sensor.

I have setup a small diagram that works with a trigger to have a minimum level at the input and then a short delay for stable signal. This will enable a threshold to keep the output at the last level.

This is NOT a finished diagram but i think a nice step in the correct direction. 

P.s. keep in mind the LPG tank is never filled 100% with liquid to keep a evaporation space.