The DS-K2704X is an advanced access controller designed to support 4-door control, with the capability to extend up to 62 DS-K2M002X access modules, allowing control of up to 128 doors. It features a downstream RS-485 redundancy wiring design to ensure stable communication. The 5-channel downlink RS-485 interface supports two applications: 1) When using 4-channel RS-485 communication, the 5th RS-485 can serve as a redundant application; 2) The 4-channel RS-485 forms two groups of dual-bus loops with physical isolation, with a recommendation of no more than 16 access modules per loop bus. Configuration management is web-based, eliminating the need for additional software. The controller supports professional access control applications such as multi-door interlocking and anti-passback, and it includes backup battery access with charging and discharging capabilities. Status indicators for power supply, communication, and operation facilitate easy equipment health detection.