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Installation Instruction ASB 150 02 > Boards For ASB 150 02

## BTU-B2 (ROF 157 5121/_)

#### Applies for indices 4 and 5

#### DIP-switches position 410-417

These switches control S- and T-interface termination and S-interface power feeding on the link 0...7.

Note

At the end of each line a termination resistor must be installed (e.g. in the last wall outlet).

The switch 1 selects the termination on the transmitter interface and switch 2 selects the termination on the receiver interface. Switches 3 and 4 enable remote power feeding to ISDN terminals connected to a link. When connected as S-interface switches 1...4 should be set to ON.

#### Switch position 418

Note

When selecting S- or T-interfaces start by setting the T-interfaces using switches 4, 3, 2 and 1 in consecutive order then set the S-interfaces starting with switches 1, 2, 3 and 4.

#### Settings of the S-interface

Choose with RASC the configuration of the interface:

- Extended passive bus (default setting)
- and Short passive bus.

#### Ranges on the interface

The BTU-B is equipped with the S/T Bus Interface Circuit eXtended (SBCX). This circuit offers the advantage of covering a higher attenuation on cables.

The standard S/T-interface specification considers cables with 6,5 dB attenuation equivalent to about 1000m cable length in single terminal configuration.

Using the S/T Bus Interface Circuit eXtended (SBCX) up to13 dB line attenuation can be covered. The figure below shows the ranges using standard 0.6 mm diameter twisted pair unshielded cables with a capacitive load of max. 30nF per km and the terminal equipment (refer to documentation of the TE) is also equipped with a SBCX or equivalent.

##### Short passive bus

##### Extended passive bus

#### Abbreviations:

TE |  | Terminal Equipment

TR |  | Termination Resistor (installed at the end of the interface line. Use outlets with resistor mounted)

|  | Outlet according to IEC 603-7 with termination

|  | Outlet according to IEC 603-7 without termination

#### Wall outlet connection

Revision: A © Ericsson Enterprise 2003