Jump to content

Recommended Posts

  • MVP 2022
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.

Link to comment
Share on other sites

  • MVP 2022

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

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...