The ABB BE/S4.20.3.2 KNX Binary Input is a modular DIN-rail device (MDRC) that scans 4 independent potential-free (floating) contacts and publishes their states on the ABB i-bus® KNX network. Contact scanning uses an internally generated pulsed scanning voltage, so no external supply is required at the input terminals — the module is powered entirely from the KNX bus.

Each channel has a manual operation pushbutton for testing and override during commissioning. Input states are indicated by yellow LEDs. The device supports KNX Data Secure for encrypted telegram communication on secure-enabled KNX lines.

Key Features — Contact Scanning and Data Secure

• 4 digital inputs: Independent detection of floating contacts from switches, pushbuttons, relays, or conventional sensors.
• Contact scanning: Internal pulsed scanning voltage — no auxiliary power at inputs.
• Manual operation: Dedicated pushbutton per channel for on-site testing.
• Status indication: Yellow LEDs show input state.
• KNX Data Secure: Supported on secure-enabled segments.
• Bus powered: No separate auxiliary supply — powered via KNX TP only.

At a Glance

Specification	Detail
Product type	KNX Binary Input — 4-fold, Contact Scanning, Data Secure
Order code	BE/S4.20.3.2 (2CDG110276R0011)
Digital inputs	4 (floating contacts)
Scanning method	Internal pulsed scanning voltage
Manual operation	Yes — pushbutton per channel
KNX Data Secure	Supported
Modular width	2 MW
Mounting	DIN rail (35 mm)
Bus system	KNX twisted pair (TP)

Full electrical ratings are listed under Technical Specifications. Datasheets, manuals, ETS application, CAD, and declarations are under Downloads.

Applications

• Conventional switch integration: Connect potential-free wall switches, door contacts, or alarm panels to KNX.
• Technical monitoring: Read fault/status contacts from HVAC plant or building services.
• Secure segments: Deploy with Data Secure-enabled couplers such as the LK/S 4.2.