What is OPC and why is it used in industrial automation?

OPC (Open Platform Communications, originally OLE for Process Control) is a standard for industrial data exchange between different vendors equipment. Benefits: vendor-independent communication, standardized data access, reduces custom driver development, and simplifies system integration. Types: OPC DA (Data Access - real-time data), OPC HDA (Historical Data Access), OPC A&E (Alarms and Events), and OPC UA (Unified Architecture - modern, secure, platform-independent). OPC servers connect to PLCs; OPC clients (HMI, SCADA, historians) read/write data.