GDK-100
DIGITAL KEY TELEPHONE SYSTEM
127
3.5.7.4
Terminating Resistors on Basic Rate interface(BRIB/STIB)
Terminating resistors are required on each line of BRIB/STIB for the proper operation. Switchable
terminating resistors are introduced on BRIB issue 3 or later version and STIB issue 2 or later version. So
switches on each line of the board should be ON to terminate them when installing line.
But terminating resistors are not introduced on BRIB issue 2 and STIB issue 1, which versions are officially
production stopped. So the external terminating unit should be required to terminate them if BRIB is issue 2
or earlier, and STIB is issue 1. The external terminating unit can be locally got, otherwise 2923NP1656,
which is the terminating unit provided by LGIC, can be used.
Note:
1. R is 100 ohm terminating resistor, and the line is terminated at 100 ohm when switches are ON.
2. SWx means terminating switches on each interface of BRIB/STIB. See clause 3.4.6.1 and 3.4.6.2.
Figure 3.5.7.4.a
Terminating method of BRIB/STIB with switchable terminating resistors
BRIB (issue 3 or later)
STIB (issue 2 or later)
RJ45 type jack
TX+
TX-
RX+
RX-
3
6
4
5
RX+
RX-
TX+
TX-
3
6
4
5
OR
T interface
: BRIB and
STIB (T)
S interface
: STIB (S)
SWx
R
R
ON
SWx
R
R
ON
From/To
BRI Line
From/To
ISDN Terminal
Figure 3.5.7.4.b
Terminating method of BRIB/STIB without switchable terminating resistors
Note: R is 100 ohm terminating resistors.
BRIB (issue 2 or earlier)
STIB (issue 1)
RJ45 type jack
TX+
TX-
RX+
RX-
3
6
4
5
RX+
RX-
TX+
TX-
3
6
4
5
OR
T interface
: BRIB and
STIB (T)
S interface
: STIB (S)
From/To
BRI Line
From/To
ISDN Terminal
R
R
R
R
External terminating Unit