Design of a Universal Control Box for Energy Storage Fire Protection Intake/Exhaust Devices Based on Modbus 485Li Zhi¹, Wang Qingkun², Yu Sihan³, Cui Bingyan?

New national standards (GB/T 44026-2024, GB/T 42288-2022) require that the fire alarm host display the real-time status of intake/exhaust devices and enforce explosion?proof ventilation. To address the problems of existing control boxes lacking communication capability and being unsuitable for built?in installation inside explosion?proof fans or battery compartments, a universal intake/exhaust control box with Modbus 485 communication is designed. With a Siemens S7?200Smart SR20 PLC as the core, the box integrates components such as circuit breakers and relays, is independently installed in a safe area outside the compartment, supports manual/automatic dual modes, and uploads operation/fault status and receives remote start/stop commands via a custom Modbus RTU point map. The manual/automatic modes respond stably, remote start and status upload delays are ≤1000?ms, communication success rate is 100%, reliable operation is achieved from –10?°C to 55?°C, and the box is compatible with devices from multiple brands. It fully meets the explosion?proof safety requirements of the national standards, significantly improves the intelligence and maintenance convenience of energy storage fire protection systems, and has promising application prospects.