ABB BE/S4.20.3.2 is the ABB i-bus® KNX Binary Input, 4-fold, Contact Scanning, Manual Operation, MDRC. It brings 4 conventional binary signals into KNX and is intended for 35 mm DIN-rail installation in an electrical distribution board. Its inputs are designed for floating contacts using an internally generated pulsed scan of ≤ 35 V DC and ≤ 0.1 mA.

Typical sources include wall switches and pushbuttons, reed contacts, relay contacts, door/window contacts, and potential-free fault or limit contacts. The device is powered from KNX TP at a rated 30 V DC (permitted bus range 21…31 V DC), draws < 5 mA, and has bus-side power loss ≤ 250 mW. KNX Data Secure is supported when commissioned accordingly in ETS.

Input Behaviour and Model Selection

The .20 version supplies its own low-current scan and must only be connected to floating contacts. A .230 version is required when the field signal itself carries voltage.

• Input count: 4 binary inputs.
• Signal specification: Internal pulsed contact scan ≤ 35 V DC, scan current ≤ 0.1 mA, and field cable length ≤ 100 m.
• Input mixing: All inputs are intended for floating contacts; the voltage-input mixing rules of the .230 range do not apply.
• Manual operation and status: Front-panel controls allow input operation to be tested locally, while yellow LEDs show the selected input states and support commissioning and fault finding.
• KNX security: KNX Data Secure protects group communication when the project and peer devices are configured for secure operation.

ETS Functions

The official ABB ETS application provides channel functions for switching, dimming, shutter/blind control, scenes, pulse counting, sequences, multiple operation, and logic or fault-message processing. Functions and communication objects are assigned per the selected application parameters; download the matching ABB .knxprod file below rather than reusing an application from an older BE/S generation.

At a Glance

Specification	Detail
Catalog description	Binary Input, 4-fold, Contact Scanning, Manual Operation, MDRC
Order code	BE/S4.20.3.2 (2CDG110276R0011)
EAN	4053546110821
Inputs	4; floating-contact scanning
KNX supply	21…31 V DC; rated 30 V DC; current < 5 mA
Power loss	≤ 250 mW
Security	KNX Data Secure
Dimensions (H × W × D)	90 × 36 × 63.5 mm (2 MW)
Net weight	0.078 kg
Protection	IP20; protection class II
Operating temperature	−5…+45 °C

Installation and Safety

Installation and commissioning must be performed by a qualified electrician in accordance with the ABB instructions and applicable electrical rules. Mount the MDRC device in a suitable enclosure on 35 mm DIN rail, maintain separation between KNX SELV wiring and other circuits, and disconnect hazardous voltages before wiring. Do not apply an external voltage to the contact-scanning terminals.

Use the official technical data, product manual, installation instructions, connection diagram, dimensional drawing, ETS application, declaration, and environmental profile listed in Downloads for design and commissioning.