What is OPC and why is it important for industrial automation?

OPC (originally OLE for Process Control, now Open Platform Communications) is a standard for data exchange between automation systems. Classic OPC: OPC DA (Data Access) for real-time data, OPC HDA (Historical Data Access) for historian data, OPC AE (Alarms and Events). OPC UA (Unified Architecture): platform-independent, secure (encryption, authentication), information modeling capability, replaces classic OPC. Benefits: interoperability between different vendor systems, reduced custom integration, standardized data access, and enables enterprise integration. OPC servers provide data from control systems; OPC clients (SCADA, historians, MES) consume data. Essential for open architecture automation.