The BEG PD9-KNX-DX is Europe's most widely installed ceiling presence detector for KNX systems — a 360° PIR sensor with integrated lux photocell, native KNX TP bus interface, and ETS6 application program supporting absence detection, constant-light control, and corridor step-dim logic. Unlike 0-10V or relay-output PIR sensors that require additional KNX binary input modules, the PD9-KNX-DX connects directly to the KNX bus and communicates ETS6-programmed group addresses for movement, absence, and daylight — no extra hardware, no gateways.

Hardware installation

The PD9-KNX-DX mounts in a standard 100mm ceiling knockout or suspended ceiling tile — the sensor housing snaps into the 72mm opening with three spring clips. The KNX bus connection (red + / black -) terminates at the two-pin push-connector on the sensor PCB. Bus current: 8mA standby (included in PS640 current budget). Physical detection zone at 2.5m mounting height: 10m diameter. At 3.0m: 9m diameter. At 4.0m: 7m diameter. Photocell window is on the lower face of the sensor — ensure no luminaire illuminates directly into the sensor face (causes false lux readings, preventing lights turning on even when below setpoint).

ETS6 application download and parameter overview

Download the BEG PD9-KNX product database from beg-luxomat.com or import from KNX Product Database (search "BEG PD9 KNX"). ETS6 > Catalog > Import > select downloaded .knxprod file. Add to project, assign individual address (e.g. 1.1.41). Key ETS6 parameter groups: 1) Detection: hold-on time after last movement (default 10min, range 0.5-60min), motion sensitivity (1-10, default 5), absence delay; 2) Daylight: lux threshold (10-2000 lux, default 500 lux), averaging filter (1-60s); 3) Outputs: movement trigger (1-bit DPT 1.002 or DPT 1.001), absence trigger (1-bit), lux value (2-byte float DPT 9.004), constant-light setpoint (1-byte DPT 5.001 or 2-byte float DPT 5.001).

Step 1: Configure hold-on time and absence delay

Hold-on time (also called "hold-off" or "delay-off"): time after last PIR trigger before absence detection fires. For office lighting: 10-15 minutes (prevents lights switching off while occupant is stationary). For corridor lighting: 3-5 minutes. For WC/bathroom: 5-10 minutes. ETS6 parameter path: Device > Detection > Motion timeout (seconds). Absence delay: additional delay after motion timeout expires before absence telegram is sent — useful for scenes with fade-out (e.g., dim to 10% for 2 minutes before full off). Set absence delay = fade-out duration to avoid race condition.

Step 2: Daylight threshold calibration

The integrated photocell measures ambient lux including the contribution from controlled luminaires. Initial calibration: set daylight threshold to desired maintained illuminance (e.g., 500 lux for EN 12464-1 office). With room fully occupied and all lights at 100%, confirm photocell reads above threshold — lights must NOT turn off during operation (closed-loop risk). If photocell reads above threshold at 100% lighting: the sensor receives too much direct illuminaire light; either adjust sensor position (away from direct luminaire beam) or enable "constant light control" mode with feedback-based setpoint control. ETS6 daylight threshold: Device > Daylight > Lux threshold = 500 lux. Automatic daylight inhibit: DPT 1.001 GA → sensor receives daylight override command (from scheduler or manual switch) → sensor ignores lux, always enables motion trigger.

Step 3: Group address assignment — movement and absence

Movement detection KNX object (object index 1): sends DPT 1.002 (1 = alarm = motion detected) or DPT 1.001 (1 = ON). Link to: KNX dimmer actuator GA (e.g. GA 1/1/0), HVAC thermostat occupancy input GA (e.g. GA 3/0/5), security system zone GA (e.g. GA 8/1/0). Absence detection KNX object (object index 2): sends DPT 1.002 (0 = no motion) after hold-on expiry. Link to: same dimmer GA (send 0 to turn off, or link to separate "absence" GA for step-dim logic). Daylight value (object index 3): DPT 9.004 (lux, 2-byte float). Link to: BMS energy monitoring GA, KNX light controller input. Motion orientation light output (object index 4): DPT 5.001 (0-100% light level for "orientation level" — e.g., 10% when no motion in occupied building): link to dimmer absolute level GA. ETS6 download: standard ETS6 download via KNX TP. After download, test: wave hand under sensor → ETS6 Group Monitor shows movement = 1 telegram on movement GA.

Step 4: Corridor step-dim logic (no external timer needed)

BEG PD9-KNX supports a 4-step corridor lighting profile natively in ETS6 parameters without external logic blocks: Step 1 (no motion): orientation level (e.g. 10% DPT 5.001 on GA 1/1/1). Step 2 (motion detected): active level (e.g. 100% DPT 5.001 on GA 1/1/0). Step 3 (hold-on expired): dim down to orientation level over fade time (e.g. 60 seconds). Step 4 (absence confirmed): send absence DPT 1.002 = 0 on absence GA. ETS6 parameter path: Device > Corridor function > Enable corridor function = Yes. Corridor activation level = 100%. Corridor orientation level = 10%. Fade time to orientation = 60 seconds. Corridor function avoids the need for ETS6 logic blocks for basic corridor dim — commissioning is entirely within the PD9-KNX ETS6 application, reducing project complexity significantly.

Step 5: Constant-light control configuration

Enable constant-light control: Device > Constant light > Enable = Yes. Setpoint lux = 500. Output type = DPT 5.001 (0-255, for 1-10V dimmer) or DPT 5.001 to KNX DALI gateway. PI controller parameters: P-gain = 5, I-time = 30s (adjust on-site). The constant-light controller increases dimmer level when measured lux drops below setpoint (cloud cover, dusk) and reduces when above (bright daylight from windows). Link constant-light output GA (object index 5) to KNX DALI gateway or dimmer actuator level input GA. Note: do not link both movement/absence triggers AND constant-light output to the same dimmer level GA — they will conflict. Use separate KNX group addresses: GA 1/1/0 = on/off (from movement), GA 1/1/1 = absolute level (from constant-light controller), dimmer configured in ETS6 to accept both independently.