293
6620-3201
20.2.1 Confi guring the X.21 Daughter Card
The X.21 daughter card compatible with the IR2140 and IR2420 routers has three internal jumpers
that determine the clock mode. By default, these are set so that the unit acts as a clock sink. For
correct
X.21 operation the jumper settings must match the setting of the
Clock source
parameter con
fi
gured
on the
Confi gure
>
Sync ports
page. To change this you will need to open the unit by removing the
four rubber feet and
fi
xing screws. Having done this, carefully remove the case lid and locate the X.21
adapter card.
The correct settings for clock source or clock sink operation are shown below:
Having set the links correctly, reassemble the case ensuring that the lid is correctly oriented.
