Terminating BNC Wordclock Distribution 131
D24—Owner’s Manual
Terminating BNC Wordclock Distribution
When a wordclock signal is distributed via BNC cables, it must be terminated correctly.
Termination is typically applied at the last device, although it depends on the distribu-
tion method being used. The D24’s WORD CLOCK 75Ω TERM/THRU switch allows
the D24 to be connected in a variety of ways. The following examples show three ways
in which a wordclock signal can be distributed and how termination should be applied.

Wordclock Distribution Box

In this example, a dedicated wordclock distribution box is used to supply a wordclock
signal to each device individually. Termination is applied at each device.

Bus Distribution

In this example, the wordclock signal is distributed via a common bus. Termination is
applied at the last device only.

Daisy Chain Distribution

In this example, the wordclock signal is distributed in a daisy-chain fashion, with each
device feeding the wordclock signal on to the next device. Termination is applied at the
last device only. This method of distribution is not recommended for larger systems.
Device-A
Termination = ON
Device-B Device-C Device-D
Termination = ON Termination = ON Termination = ON
WC OUT
(BNC)
Wordclock
master Wordclock
distribution box
Wordclock slave Wordclock slave Wordclock slave Wordclock slave
WC IN (BNC) WC IN (BNC) WC IN (BNC) WC IN (BNC)
Device-A
Termination = ON
Device-B Device-C Device-D
Termination = ON Termination = ON Termination = ON
Wordclock
master
Wordclock slave Wordclock slave Wordclock slave Wordclock slave
WC IN (BNC)
WC OUT (BNC)
WC IN (BNC) WC IN (BNC) WC IN (BNC)
Device-A
Termination = OFF
Device-B Device-C
Termination = OFF Termination = ON
Wordclock
master
Wordclock slave Wordclock slave Wordclock slave
WC IN
(BNC)
WC OUT
(BNC)
WC OUT (BNC)
WC IN
(BNC)
WC IN
(BNC)
WC OUT
(BNC)