The ABB US/U2.3 Universal Interface 2-fold is a compact flush-mounted KNX I/O module with 2 independently configurable channels. Each channel can be parameterised as an input (conventional push-buttons, auxiliary contacts) or as an output (local LED indication). The device bridges standard wall controls to the KNX bus without replacing existing switch hardware.

The US/U family supports KNX Data Secure for encrypted telegrams. Channels also accept analog signals (0 … 10 V / 4 … 20 mA), extending use beyond simple digital switching. At just 12 × 39 × 40 mm and 0.25 W power loss, it fits discreetly behind switches or in flush boxes.

Key Features — 2-Channel Universal I/O

Channel Configuration

• 2 channels: Each independently set as digital input or LED output in ETS.
• Digital inputs: Pulsed 20 V input for conventional push-buttons and auxiliary contacts.
• LED outputs: 3.3 V DC at up to 5 mA per channel for status indication.
• Analog inputs: 0 … 10 V or 4 … 20 mA per channel for sensor integration.
• KNX Data Secure: Encrypted communication when enabled in the project.

Installation

• Flush-mounted: Installed behind the switch plate or in a flush box.
• Compact footprint: 12 × 39 × 40 mm (W × H × D).
• Low bus load: 0.25 W power loss.

At a Glance

Specification	Detail
Product type	Universal Interface — 2-fold, flush-mounted
Order code	US/U2.3 (2CDG110308R0011)
Channels	2 (input or output, per channel)
Digital input	20 V pulsed
Analog input	0 … 10 V / 4 … 20 mA (2 channels)
LED output	3.3 V DC, max 5 mA
Security	KNX Data Secure
Dimensions (W × H × D)	12 × 39 × 40 mm
Power loss	0.25 W
Protection	IP20

Full electrical ratings and classification codes are listed under Technical Specifications. Technical data, product manual, installation instructions, ETS application, CAD, and connection diagrams are under Downloads.

Applications and KNX Integration

• Conventional push-buttons: Connect existing momentary or toggle switches to KNX without replacing faceplates.
• LED feedback: Drive status LEDs on multi-gang switches from KNX group addresses.
• Analog sensors: Read 0 … 10 V or 4 … 20 mA signals from third-party sensors on the bus.
• Actuator pairing: Inputs typically control switch or dimming actuators such as the UD/S4.210.2.1 Switch Actuator 4-fold.
• Panel alternatives: Where a full touch panel is preferred, consider the ABB RoomTouch 4-inch KNX Control Panel.

Choosing US/U Universal Interfaces

For four channels in the same compact housing, choose the US/U4.3 KNX Universal Interface 4-fold. For dedicated digital inputs without per-channel LED drive, the BE/S10.20.3.2 Binary Input 10-fold Data Secure offers ten inputs in a DIN-rail module. All devices require a KNX power supply such as the SV/S 30.320.1.1 or SV/S 30.640.3.1.