What types of redundancy are used in DCS systems?

DCS redundancy types: Controller redundancy - paired controllers in hot standby, automatic switchover on failure; Network redundancy - dual communication paths with automatic failover; Power supply redundancy - dual supplies with load sharing or standby; I/O redundancy - duplicate I/O cards for critical loops; Server redundancy - historian, asset management, OPC servers in pairs; and Operator station redundancy - multiple stations for availability. Redundancy modes: hot standby (backup ready to assume control immediately), warm standby (backup synchronized but needs activation), cold standby (backup requires manual configuration). Critical loops may have triple modular redundancy (TMR) with voting.