Water meter

[Magnien]

I want to make a water meter, with a flow sensor.the flow rate can vary during filling so I think I will record the flow rate every 1/2 second but I am not sure of the final precision!

[Joe Tauser]

3 hours ago, Magnien said:

I am not sure of the final precision!

Me, neither.

You'll have to give us information on your pipe size, flow sensor make and model, which PLC model you want to use, and your anticipated flow rate range before any of us can give you direction.

Joe T.

[Magnien]

Hi joe , 

we use V350 , with flow meter https://www.bene-inox.com/fr/debitmetre-vortex-sortie-4-20-ma-7394/

the diameter of the flow meter is 1” pouces 

[Joe Tauser]

Need the full model number of the V350.  They have different I/O boards.  There is a very large difference in the analog input resolution between a -TA24 and a  -TR20.

 

Joe T.

[Magnien]

Sorry , it’s a V350 J RA22

[Joe Tauser]

OK - so you've got the 20 mm ID unit where 4/20 mA = 5 to 85 l/min: 

The -RA22 is the high resolution analog input board, where 0 - 20 mA = 0 to 16384 counts.  4 mA = 3277 counts, so your 4/20 signal will be spread over 13,107 counts.  

If you use a virtual decimal place at 0.xx, you can scale your flowrate input to 5.00 to 85.00 l/min.

The -RA22 has four analog inputs which are dedicated to input type.  AI 0 and AI1 are for thermocouples and 100 ohm RTDs, and AI 2 and AI 3 are for 0-10VDC or 4/20 mA.  You'll need to set the jumpers inside the unit to select the 4/20 input.  I'd recommend connecting your flowmeter to AI 2.

Your linearization block can be set up like this:

 

I've attached a program showing this.  How often you sample it and the math to totalize flow is up to you.  Since your input flowrate can be up to 8500, I'd recommend doing your math in MLs as you will quickly overrun the maximum value of an MI which is 32,727.

To answer your question, your precision is 0.01 l/min.

Joe T.

Flowmeter scaling JT.vlp

[Magnien]

Hi  joe

thank you very much for these explanations and your professionalism. I will test

[Magnien]

now, I would like to create a water meter with this flow rate: with an example selection: 100 liters.I press a START button, a solenoid valve opens and the water fills a tank. As soon as 100 liters are reached, the solenoid valve closes.

[Magnien]

see my program 

flow meter.vlp