30
MULTIPORT CSU/DSU
3. While keeping the module’s faceplate parallel with the CSU/DSU’s rear
panel, slide the module straight in, so that the card-edge contacts line up with
the socket inside the chassis.
NOTE
The card-edge connector should meet the socket when it is almost all
the way into the chassis. If you encounter much resistance, remove the
module and repeat steps 2 and 3.
4. With the card edge contacts aligned with the socket, firmly seat the module by
using your thumbs to apply pressure directly to the right and left edges of the
module faceplate. Applying moderate and even pressure should be sufficient
to seat the module. You should hear it “click” into place.
5. To secure the module in place, push the thumbscrews into the chassis and
turn the screws clockwise to tighten.
To remove an interface module:
1. Turn the power switch off. Leave the power cord plugged into a grounded
outlet to keep the unit grounded.
2. Loosen the two thumbscrews on the module by turning them counter-
clockwise.
3. Grasp the two thumbscrews and gently pull the module from the CSU/DSU.
Apply equal force to the thumbscrews to keep the module straight while you
remove it.
4.1.2 C
ONNECTING TO A
DTE D
EVICE
The serial port on most interface modules (all except the X.21 module) is hard-
wired as a DCE. Therefore, these modules plug into a DTE such as a terminal, PC,
or host. When connecting to your DTE device, use a straight-through cable of the
shortest possible length—we recommend 6 feet (1.8 m) or less. When purchasing
or constructing an interface cable, refer to the pin diagrams in
Appendix A
as a
guide.
4.1.3 C
ONNECTING TO A
DCE D
EVICE
If the CSU/DSU’s interface module is hard-wired as a DCE (all except the X.21
module), you must use a null-modem cable when connecting to a modem,
multiplexor, or other DCE device. This cable should be of the shortest possible
length—we recommend 6 feet (1.8 m) or less. When purchasing or constructing a
null-modem interface cable, use the pinout diagrams in
Appendix A
as a guide.
