Technical data

24
Switch Termination Resistors
The termination resistors for the internal and external S
0
ports are to be
switched on or off with help of the DIL switch on the circuit board (see
Pic. 23). The external S
0
port „S
0
1“ is not terminated.
If the corresponding S
0
port of the PBX is at the beginning/end of sev-
eral units or if there is only one connection between two units, the
appropriate termination resistors need to be activated.
This is the case e.g. if the PBX is connected directly to the NTBA as a
single device which is always the case with a PTP connection. (Excep-
tion: An ISDN connection box with integrated terminal resistors was
switched in between).
The termination resistors needs to be activated e.g. if you lay an internal
S
0
bus to two directions starting at the corresponding internal S
0
port.
But you also have to deactivate the termination resistors if you con-
nected an external S
0
bus directly to the NT with termination resistors
in the last connection box and if you connect the PBX to one of these
connection boxes.
In the individual installation chapters the different possibilities will be
explained in detail again. (see chapter Installation of Wall Jacks (inter-
nal S0 Port) on page 21 and chapter Install Wall Jacks (External S0
Bus) on page 20).
Switch Termination Resistors
ON
12
on / off
Ter m.
ON
12
on / off
Ter m.
Pic. 23: Termination resistors
switched on switched off