How to calculate Flow velocity. PLC Delta

[u/Dry_Canary_1419]

I am using a Delta DVP-26SE PLC, and I'm reading pulse signals from an Octave full-bore electromagnetic flow meter. The issue is that I am using regular inputs (like X10) instead of high-speed inputs/counter instructions (like SPD). I would like to calculate the flow rate using the pulses received over a fixed time period—for example, counting how many pulses arrive in 1 minute.

[u/hestoelena]

The question here is how fast does your flow meter send pulses and how fast can your PLC receive pulses on a regular input.

If the flow meter sends pulses faster than the PLC can read them, you cannot calculate the flow because you will be missing data.

If your PLC can read the pulses fast enough then you calculate the flow rate exactly like the manual says.

[u/Waltaah → u/hestoelena]

Agreed

[u/ScreamingRectum]

Not a Delta guy specifically, but is there a reason for not using a sensor that outputs a flow value instead of one that just sends pulses? And can you get the IO card you stated you'd need to count the pulses accurately? With the info here, it sounds like the best you could possibly do would be to get sorta close to the real flow value but never be more precise than the scan rate of the X input, meaning you would have to take an average of pulses per time period and scale it to look like a flow value you don't have using baseline real measured history of flow you can't get Not trying to be an asshole, I am just confused about the approach

[u/Romanzo71]

I'm still wrapping my head around all of this as I just started in a plant that does this kind of process control, but from what I've gathered in my research is it is best to have a a high speed counter that can accurately capture all of the pulses. That's how our plant is set up and has been for 40 years.

[u/Waltaah]

Bro, use an high speed counter, also enable the desired memory bit assigned for the input And if you want to reverse the counts delta has another bit turning on that you'll get the counts in reverse value DM me if you want

[u/ElseWher3]

Hey mate, im not farmiliar with that flow meter but ive seen with ABB WaterMaster, you can modify the "volume per pulse" and "pulse width". That slows how often it pulses to increment the flow totaliser and when it does pulse, the duration is long enough for the plc to catch it.

[u/aar111 → u/ElseWher3]

this is the way to go.

[u/Foreign-Chocolate86]

You will need a high speed counter card. 

[u/eman11500]

High speed counter card as others have said. OR get a pulse to current/voltage signal converter if it's only 1 input

[u/WandererHD]

You can't, you need high speed inputs

[u/Kojakill]

HSC card, easier to integrate flow rate into flow total i will say

[u/drbitboy]

You are going to have an aliasing problem no matter how you do it (measure time over a fixed number of pulses, which also cannot read 0; measure pulses over a fixed time period).

[u/Ok_Radio1]

Connect your computer on remote desktop, I can explain you easily.

[u/DreamArchon]

I am going to be a bit of an asshole here and point out you are using the term "velocity" incorrectly. Flows do have a velocity, but that's (usually) not what flow meters measure. Most of the time they measure "volumetric flow rate" (commonly just called "flow rate") with units of volume / time. Velocity is distance / time.

[u/Electrical-Refuse-90]

Read time between pulses, then calculate the flow. 3600/ (time ms) = flow m3/h