What are the different controller modes (auto, manual, cascade)?

Auto mode: controller automatically calculates output to maintain setpoint - normal operating mode. Manual mode: operator directly sets controller output - used during startup, maintenance, or troubleshooting. Cascade mode: controller setpoint comes from another controller's output rather than operator - secondary controller in auto with remote setpoint. Other modes: Local (setpoint adjusted at field), Remote (setpoint from DCS), and Tracking (output follows external signal). Mode transitions must be bumpless to avoid process upsets.