An Access Controller is the central hardware component of an access control system. It makes real-time decisions about whether a person or vehicle is permitted to enter or exit a secure area, building, or room. It essentially serves as the "brain" of the entire security system.Request for Access: A person presents their credentials (such as an access card, biometric fingerprint, or mobile credential) to a reader. Data Transmission: The reader reads the information and immediately transmits it to the Access Controller. A modern Access Controller offers advanced features beyond basic locking: User Management: Centralized control to easily add, modify, or delete user profiles, access credentials, and permission levels. Time and Zone Control: Allows administrators to set precise schedules and zones for access (e.g., an employee may only have access to a specific floor from 9 AM to 5 PM). Anti-Passback: A feature that prevents one person from passing their credential back to another person to gain entry, ensuring credentials are used sequentially for entry and exit. Audit Trail: Creates a detailed, tamper-proof log of every access event (who went where and when), which is vital for security auditing and investigations. System Integration: It can interface with other security systems like CCTV cameras, fire alarms, and intrusion detection systems. For instance, a fire alarm can trigger the controller to automatically unlock all doors for emergency evacuation.