The ABB US/U4.3 KNX Universal Interface 4-fold is a compact flush-mounted KNX I/O module with 4 independently configurable channels. Each channel can be parameterised as an input (conventional push-buttons, auxiliary contacts) or as an output (local LED indication). It is the higher-density sibling of the 2-fold US/U2.3, sharing the same housing dimensions and ETS application.

The US/U family supports KNX Data Secure for encrypted telegrams. All four channels accept analog signals (0 … 10 V / 4 … 20 mA) in addition to digital switching. At 12 × 39 × 40 mm and 0.25 W power loss, four channels fit in the space typically occupied by one DIN-rail module.

Key Features — 4-Channel Universal I/O

Channel Configuration

• 4 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 on all four channels.
• 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) — same size as the 2-fold variant.
• Low bus load: 0.25 W power loss.

At a Glance

Specification	Detail
Product type	Universal Interface — 4-fold, flush-mounted
Order code	US/U4.3 (2CDG110309R0011)
Channels	4 (input or output, per channel)
Digital input	20 V pulsed
Analog input	0 … 10 V / 4 … 20 mA (4 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

• Multi-gang switches: Interface up to four rockers or contacts from a single flush module.
• 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 two channels when wiring density is lower, choose the US/U2.3 Universal Interface 2-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.