Use Increasemental Encoder to Calculate Flowrate Question

Hi Everyone,

I am new to srevo control, and hope to you guys can help me.

I have a Siemens s120 controler and drive, drive a cylinder up and down to supply flow rate.

It is a simple speed control with give servo the RPM speed command, I mapped the encoder vaule back to the AB plc, the value is from 0 to big number (32 bit)
I have pusles per litter information to display the actual flowrate, right now the question is that how can I monnitor the pluses change rate acrrutly?

The genetic moudle RPI for s120 controller is 20ms, I guess I can record the pluses vaule until it changes then compare them, the different will be the pluses during the 20ms, right? If this is wrong, is there a better way to do this?

Thank you!

To get running averages of a system, you have to specify a sample time τ, get the quantity δ in the given τ, and for dynamic systems, get the value using mathematics for t=0->τ

Set δ = 0 in the beginning of measurement.
So, for t in (0,τ] rate = δ /τ,

for n=1->inf, rate = δ/{τ-t(n-1)}

So, your sample times would basically be based on timesteps indexed by n. Delta would be your current pulses, delta(n-1) would be previously recorded pulses, and t-t(n-1) would be your timestep length. Make that using function blocks for bonus points.

Regards,
-PreLC