I want to know about the difference between PLC and SCADA.
A PLC is a programable logic controller not necessarily using feedback but usually does where as SCADA stands for System Control And Data Acquisition, data acquisition being of primary importance
When I worked in the chip fabs out west , allot of PLC made up there SCADA system. it collected every kind of information and data you can imagine, from moisture, particle, O2 ,temps , valve positions you name it they had 3 and a Backup. I added and implemented some labview Systems to replace them.