> Does any one can explain me in details that what is Difference Between HMI , SCADA , Expert Control system or all these are same?
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HMI, which stands for Human Machine Interface, is usually classified as a graphical user interface at the machine level, which provides control and data visualization for a single machine or small area, and is almost always mounted on or near the machine. An HMI usually provides low level control and basic data visualization, from text only displays to graphical displays.
SCADA, which stands for Supervisory Control and Data Acquisition, is a higher level system that provides summary control and data processing for a larger area within a plant or for the entire plant. SCADA usually provides more overview and historical type data and usually has more advanced functionality that an HMI.
Expert Systems, which are still pretty scarce in practical manufacturing applications, make production and operations decisions on their own using data obtained from the plant. Similar in scale to a SCADA system, an expert system takes the operator or manager somewhat out of the loop to make decisions based on a previously determined rule set. Expert systems are also implemented on lower scale applications, such as sorting algorithms in packaging machines, or stacking algorithms in auto plants. The expert system or algorithm takes data from the controllers on system status, throughput information and the like , and then determines where to route packages or cars without human interaction. Usually the expert system allows operators to "tweak" the parameters to allow some control over the algorithm.
Hope that treatise helps!
David Klebe
WebDock Information and Automation Systems
