SiemensWG1148-1AB02KNX / instabus EIB RS 232 Serial Data Interface, 9-Pin Sub-D, DIN Rail N-System

Product Description

What this part is

A Siemens instabus EIB (KNX) RS 232 serial data interface, catalogue designation N 148/02. It provides a point of attachment between a KNX twisted-pair bus line and the serial port of a PC, so that a commissioning tool can address devices, download parameters, read group values and run bus diagnostics. The bus side terminates on the standard KNX bus connector; the PC side is a 9-pin Sub-D socket carrying RS 232 at 9600 bit/s over a data cable of up to 15 m.

Decoding the order code

Siemens building-technology part numbers open with the 5WG1 block, which identifies the GAMMA instabus / KNX range. The following three digits, 148, are the device family — in this range the serial interface. 1AB is the N-system DIN rail housing variant, and the closing 02 is the generation. The catalogue name printed on the faceplate, N 148/02, carries the same two fields: 148 for the interface family, 02 for the generation. Later members of the same family move to Ethernet — N 148/22 is the IP interface — so the /02 generation is the one that is specifically RS 232.

What these specs mean in practice

The unit draws its operating power from the 24 V DC KNX bus itself, so there is no mains terminal and no auxiliary supply to find. That makes it usable anywhere on an energised line, including in a panel with no spare 230 V feed. The 9600 bit/s rate is the classic EIB tool rate and is the constraint on download time for large projects; the 15 m cable limit is the RS 232 electrical limit rather than a software one. A learning button and LED on the front handle physical address assignment.

Quantity and configuration

1 Pc. Interface module only. No RS 232 data cable, no USB-to-serial adapter, no KNX bus connector block, no DIN rail and no software licence.

Installation and setup notes

The device is an N-system unit for a standard 35 mm DIN rail inside a distribution board, with the bus connector pressed onto the terminal at the top and the Sub-D socket facing the front. Protection degree is IP20, so it belongs inside an enclosure. Mass is approximately 0.14 kg. A physical address is assigned once, via the learning button, before the device answers on the bus.

Interchange guidance

Within the RS 232 generation the 5WG1 148-1AB01 and 5WG1 148-1AB02 are the direct predecessors and successors of one another and share the serial connection scheme. The IP variants N 148/12 and N 148/22 are a different physical layer on the PC side and are not a drop-in substitute where a serial port is required. KNX USB interfaces such as the N 148/21 are likewise a different host connection.