yes it is interesting..i am working on a project pipeline leak detection ..the project containing ultrasonic flow meter and plc ..i need to monitor any change for flow value and pressue ..the historical trend will show this but i need to make an alarm on changing time or specific variation time ..can scada do it ?
I would look at AdvancedHMI. This is open sourced and includes the drivers for several PLC manufactures as well as some common protocols. https://sourceforge.net/projects/advancedhmi/
Since this uses visual studio, there are several examples of storing information into databases and doing simple trend calculations.
Ex. https://www.codeproject.com/Articles/1101932/Simple-trend-calculation
You could then work on exactly how you want the triggering to take place.
You are fingerprinting. That's a tough nut to crack. Sounds like you need to watch Ramp (or decay) Rate or 2 parameters and match that to your known "fingerprint" of a bad condition.