Eaton Power Xpert 4000 (10-300 kVA three-phase online double-conversion UPS) includes a built-in Modbus TCP server on port 502. In data centres, hospitals, and industrial facilities with KNX building management, the UPS integrates as a standard Modbus device — battery SOC, load percentage, and on-battery alarm feed KNX building automation.

Register Map: Power Xpert 4000

Modbus TCP port 502, unit ID 1. Holding registers (FC3):

- Register 16: Output voltage L1-N, uint16, Vx10 (e.g. 2300 = 230.0V) - Register 17: Output voltage L2-N, uint16, Vx10 - Register 18: Output voltage L3-N, uint16, Vx10 - Register 24: Output frequency, uint16, Hzx10 (e.g. 500 = 50.0 Hz) - Register 28: UPS load percentage, uint16, 0-100 - Register 30: Battery SOC percentage, uint16, 0-100 - Register 31: Battery runtime remaining, uint16, minutes - Register 128: UPS status word uint16 bitmask — bit 0=on battery (bypass/mains failure), bit 1=low battery (<20%), bit 2=replace battery, bit 4=overload, bit 8=bypass active

KNX mapping: register 28 -> DPT 5.001 GA (UPS load %). Register 30 -> DPT 5.001 GA (battery SOC %). Register 128 bit 0 -> DPT 1.005 alarm GA (on battery = critical alarm in KNX SCADA).

Eaton 9PX with NETWORK-M2 Card

Eaton 9PX 2200-3000 VA rack UPS: add NETWORK-M2 network card (optional accessory). Card enables Modbus TCP on port 502, SNMP v3, REST API, and MQTT. Same register map structure as Power Xpert 4000. IP address assigned via DHCP or static — configure in NETWORK-M2 web UI (http://[card-ip]). Unit ID 1. MDT Modbus gateway connects to NETWORK-M2 IP.

Alarm Routing to KNX

KNX logic (MDT Logic Controller): poll register 128 every 30s. Bitmask extraction: AND register 128 with 1 (bit 0) — if result = 1: send DPT 1.001 = 1 to KNX alarm GA. This triggers: KNX panel alarm LED activation, email notification via KNX/IP interface to building management.

Low battery alarm (bit 1): AND register 128 with 2 — if = 2: send escalated alarm GA for generator start signal (if KNX controls generator interlock).

Generator Switchover Integration

In facilities with standby generators: KNX monitors both UPS on-battery state (Modbus bit 0) and generator running state (dry contact from generator AMF panel to KNX binary input). Logic: UPS on battery AND generator not yet running AND time elapsed > 20s -> KNX output triggers generator start relay (DPT 1.001 = 1 to GA 8/1/2). When generator running confirmed (GA 8/1/3 = 1): KNX deactivates UPS low-priority loads (server room non-essential sockets) to reduce UPS runtime demand.

RS232 Legacy UPS

Eaton 9E series with RS232 port only: use USB-to-RS232 adapter + NUT (Network UPS Tools) on Raspberry Pi. NUT exposes UPS data via SNMP or custom driver. Third-party KNX/SNMP gateway (e.g. IP-Symcon with SNMP module) reads NUT SNMP output and maps to KNX GAs. More complex than Modbus TCP but achieves same result.