Fermax is Spain's largest video door entry manufacturer with 70+ years of history — the VDS (Video Door Switching) 2-wire system is installed in millions of Spanish apartment buildings. The Fermax 1490 KNX interface module bridges the VDS bus to KNX, enabling door call events to trigger lighting, HVAC, and access control automation. This guide covers VDS bus architecture, 1490 module wiring, ETS6 configuration, multi-tenant building setup, and the newer Fermax Way SIP hybrid system.

Fermax VDS 2-wire bus architecture

Fermax VDS uses a single 2-wire cable (unshielded YCYM 2×0.75mm² or equivalent) carrying: DC power (18V from Fermax switchboard), analogue video signal (625-line PAL format, 4MHz bandwidth), audio (half-duplex), and digital data (proprietary Fermax VDS protocol, not IP). VDS components: Fermax 4+N switchboard (power supply + call routing), Loft door station (flush-mount, 1 button, IP54), MDS digital monitor (4.3-inch LCD, hands-free, door open button, DoorBird-like design), Veo XS (7-inch colour monitor). Maximum bus length: 100m without repeater, 200m with Fermax 6890 bus extender. Switchboard: Fermax 6231 (1 entrance, 4 monitors), 6233 (4 entrances, 32 monitors). All VDS components use the same single YCYM cable — no separate video coax.

Fermax 1490 KNX interface module wiring

The 1490 KNX interface module (DIN-rail, 4 modules wide, 24V DC powered from KNX bus coupler): VDS bus terminals (connect to VDS switchboard secondary output — the 1490 is in parallel on the VDS bus, not in series). KNX bus terminals (standard YCYM KNX cable connection). The 1490 must be connected to the secondary output of the Fermax switchboard (the output that feeds monitors) — do not connect to primary input (door station line). Power: the 1490 draws from KNX bus (40mA) and does not require external power beyond KNX bus voltage. ETS6 programming button on 1490 face — standard KNX individual address assignment (1.1.x). Download Fermax .knxprod from fermax.com > Support > KNX > ETS files. One 1490 per switchboard (handles one VDS bus).

ETS6 group object configuration

Fermax 1490 ETS6 application group objects: (1) Door call input — DPT 1.001 (read), sends 1 when door button pressed at Fermax door station. GA: 12/0/0. (2) Door open output — DPT 1.001 (write), send 1 to open door relay (releases door strike, configurable pulse 1–10 seconds in ETS6 parameters). GA: 12/0/1. (3) Call in progress — DPT 1.001 (read), 1 while call active (monitor ringing). GA: 12/0/2. (4) Monitor answered — DPT 1.001 (read), 1 when monitor picks up. GA: 12/0/3. (5) Privacy input — DPT 1.001 (write), send 1 to activate privacy mode (VDS monitor will not ring — useful for DND from hotel card reader KNX). GA: 12/0/4. ETS6 parameters: ring time (5–60 seconds), door open pulse duration (1–10 seconds), individual apartment address on VDS bus (for multi-tenant buildings with named call routing).

Multi-tenant apartment building configuration

20-apartment building, 1 entrance: Fermax switchboard 6233 (4-entrance capacity, use 1 entrance port), 20 monitors (one per apartment). VDS monitors in each apartment: each monitor has a unique VDS address (1–20, set via DIP switch or menu). 1490 KNX module: one per entrance. ETS6 group objects: door call GA 12/0/0 → triggers entrance common lighting only (not per-apartment). For per-apartment call detection: Fermax AIO Pro switchboard (newer model with IP port) provides REST API for per-apartment call events — more advanced integration requiring software development. Simple alternative: each Fermax monitor has a built-in relay output (Fermax 1461 relay module add-on) → dry contact → KNX binary input in each apartment electrical panel → per-apartment door call KNX event.

Fermax Way hybrid SIP system

Fermax Way (2019+) is the successor hybrid system: VDS 2-wire bus physical layer + SIP over Ethernet for app integration. Fermax Way door station: VDS bus (for existing Fermax monitors) + RJ45 Ethernet (SIP trunk to Asterisk or Fermax ViM cloud). This allows existing VDS-wired buildings to add smartphone app functionality without rewiring. KNX integration for Fermax Way: same 1490 KNX module approach on VDS bus side. Additionally: Fermax Way REST API (available in developer documentation) allows HTTP POST to open door from external system (Home Assistant → KNX bridge → Fermax Way API open_door). Use REST API for remote door open from KNX scene or access event. Test by sending HTTP POST with door_open command from browser before wiring KNX.

Commissioning checklist

(1) Wire Fermax VDS bus: door station → switchboard (primary input), switchboard secondary output → monitors → 1490 KNX module (parallel). (2) Power on switchboard: verify 18V DC on secondary output with multimeter. (3) Press door station button: verify monitor rings and video appears. (4) Install 1490: connect to secondary output and KNX bus. (5) ETS6: import Fermax .knxprod, add 1490, assign address. (6) Configure parameters: ring time 30 seconds, door open pulse 3 seconds. (7) Download ETS6 to 1490. (8) Group Monitor test: press door station button → verify GA 12/0/0 receives value 1. (9) Test door open: send value 1 to GA 12/0/1 from Group Monitor → verify door strike releases. (10) Connect automation: link GA 12/0/0 (door call) to entrance lighting GA via ETS6 or logic module. Document all GAs in project handover sheet.