The ABB LL/S 1.1 Optical Fibre Interface (order code GHQ6050053R0001) couples two sections of a KNX / EIB twisted-pair line over an optical fibre link. Typical uses are long distances between buildings, electrical isolation, EMI immunity, and reducing the need for lightning / surge protection on copper cable runs between separate structures.

Two LL/S 1.1 devices are required for one transmission path. Each unit connects to the local bus with a KNX terminal and to the fibre plant via ST sockets (2 m patch cable included). Signals use two fibres suitable for 850 nm transmission. ABB states a maximum total link attenuation of 14 dB at 850 nm — example reaches: approx. 3.5 km with 50/125 µm fibre (≈ 4 dB/km) or approx. 1.4 km with 200 µm fibre (≈ 10 dB/km). Each bus section still needs its own KNX power supply.

LL/S is infrastructure — plan fibre type, connectors and optical budget from the ABB technical data before ordering. It is not an IP gateway and not a substitute for a line coupler when you only need topology filtering on copper.

Key Features — Fibre Segment Link

• Optical fibre KNX link: Couples two TP line sections with galvanic isolation via fibre.
• Long-distance examples: Up to ≈ 3.5 km (50/125 µm) or ≈ 1.4 km (200 µm) within the 14 dB budget.
• ST Tx / Rx: Separate send and receive ST sockets; LED indication of optical Tx and Rx traffic.
• Paired devices: Always order and commission as a matched LL/S ↔ LL/S path.
• MDRC 4 MW: Pro M housing approx. 90 × 72 × 76 mm (H × W × D); supply from the KNX bus (21…31 V DC).

At a Glance

Specification	Detail
Product type	Optical Fibre Interface, MDRC
Order code	LL/S1.1 (GHQ6050053R0001)
EAN	4016779392105
Link	Two devices; 850 nm; max. 14 dB attenuation
Connectors	2 × ST (Tx/Rx) + KNX bus terminal
Width / dimensions	4 MW; approx. 90 × 72 × 76 mm (H × W × D)
Supply	Via KNX bus (21…31 V DC); each side needs a PSU

Full optical budgets, wiring and installation rules are in the ABB technical data and installation instructions under Downloads.