Graphics Trends in SCADAs

Hi community,

I am doing a graphic trend for a small control system (a small SCADA), but I need information about it. The theory that is behind this small but very useful and important functionality of SCADAs. Any book, any reference any author that has written something about it, any particular peace of advice, any idea that will help me to built this widget would be very helpful.

Greetings,

Raul