Overview

TROX TVZ-D (round duct VAV) and TVLQ (sound attenuating rectangular VAV) are BACnet MS/TP devices. BACnet device ID 1-127, set via small DIP switches on the TVZ controller PCB.

RS485 Wiring and Gateway Setup

RS485 wiring: A/B/GND from TROX TVZ to LOYTEC LGATE-950 RS485 port A. Termination: 120-ohm resistor on the last device on the RS485 run. LGATE-950 web UI: Settings → BACnet/MS/TP → baud rate 9600, parity none. LGATE auto-discovers all TVZ devices via BACnet Who-Is broadcast.

Signal Table Mappings

For each TVZ, create LGATE signal table mappings: TVZ BACnet AV:3 (actual flow l/s) → LGATE input → KNX GA DPT 9.002. TVZ BACnet AO:1 (damper position %) → KNX GA DPT 5.001. TVZ BACnet AI:1 (room temp) → KNX GA DPT 9.001. KNX GA (room setpoint from MDT room controller) → LGATE output → TVZ BACnet AV:1 (minimum setpoint write).

Zone Control in ETS6

MDT SCN-LCRM.01 room controller on each KNX zone measures room temperature (from TVZ AI:1 via KNX), computes PI heating/cooling demand, and writes flow setpoint to KNX GA (maps to TVZ AV:1). Occupied/unoccupied: KNX presence detector (THEBEN dual-tech sensor) writes occupancy GA → room controller switches setpoint from 21°C (occupied) to 18°C (unoccupied, energy save) → reduced flow setpoint written to TVZ.

Full Building Example

5-storey office, 4 zones/floor, 20 TVZ units total. Single LGATE-950 handles all 20 TVZ plus additional BACnet devices (AHU, ECLYPSE room controller) — LGATE supports up to 128 BACnet devices. BACnet COV (Change of Value) subscription: configure LGATE to use COV for TVZ AV:3 — TVZ pushes updates when flow changes by 5 l/s, eliminating polling overhead on the RS485 bus.

Energy Savings

DCV based on CO2 sensors combined with VAV setpoint control reduces AHU fan energy by 30-50% versus a constant volume system.