Averaging Analog input from Flow meter

[dbh6]

@ Tom Jenkins, where did you get that formula for the filtering algorithm is it a first order filter??

 

[Fredlaroche]

I agree that physical dampening is the way to go.

Also, check your flowmeter settings, you might have some filtering options on there as well. Your problem is not uncommon at all.

 

[Paul T]

@ Tom Jenkins, where did you get that formula for the filtering algorithm is it a first order filter??

Yes... that is a classic first order filter. Usually the "1/k" term is referred to by the greek letter alpha and is restricted to 0 <= alpha <= 1. Stating it as 1/k is just a convenient way to implement the smoothing.

Nice graph... shows clearly that as you decrease alpha, you smooth the output... but that the smoothed curve now lags the real world by some amount. You have to decide how much lag your process can stand when you filter an input.

 

[goghie]

It is recommended that before flowmeter there is straight line long enough to eliminate vortexes. It should be long at least 10 times diameter of tube.

Best regard,
Vuckovic Goran.

 

[daba]

It's not about the PLC, it's about whether the flowmeter itself is giving good data.

......

Many flowmeters cannot cope too well with the sort of rapidly changing (i.e. pulsating) flowrates produced by diaphragm or peristaltic pumps.

The only technology that can give precise results are positive displacement flowmeters. There are many types available, but the important thing is that the movements inside the flowmeter are directly proportional to what flows through it, at any speed.

Some "non-contact" flowmeter manufacturers claim to have some form of pulsation compensation built-in to their software algorithm. but at the end of the day the output is only going to be an approximation, however cleverly is it obtained.