Modem Installation
2-7
3920-A2-GN31-30
November 1996
SDU is required when the modems in the carrier are controlled by an NMS, or when multiple
carriers in a cabinet configuration are to be controlled by a single shared diagnostic control panel
(SDCP). The SDCP of the COMSPHERE 3000 Series Carrier is the user interface to the
Model 3921Plus modem. A single SDCP can control up to eight carriers.
The installation of a Model 3921Plus modem varies slightly if an SDCP is installed on the front of
the carrier. To install a Model 3921Plus modem into the carrier without an SDCP, perform the
following steps:
1. At the back of the carrier, install the connector plates (Figure 2-2). Make sure the plate(s)
use the same slot positions as that intended for the modem.
Loosely fasten the plate(s). This allows for slight adjustments later when installing the
modem.
2. At the front of the carrier, hold the modem vertically, with the latch on its faceplate in the
open position, and insert it into the top and bottom card guides of one of the slots
numbered 1–15 (Figure 2-3).
Slide the modem into the slot, aligning the modem with the connector plates, until the
backplane connector and DTE connector seat firmly into the back of the carrier. The
faceplate latch automatically closes as you push the modem into the carrier. To lock the
modem into the carrier, press the faceplate latch until a “click” is heard.
3. If the carrier is ON, the Power LED on the faceplate of the Model 3921Plus lights. After
several seconds the modem completes its power-up self-test, in which all faceplate LEDs
light.
Return to the back of the carrier and tighten the connector plate(s).
DTE A
DTE B
DTE A
DTE B
MULTIPORT
BACK
CONNECTOR PLATES
495-14696
FUTURE USE
V
.35
(3600/3500)
RS366A/V
.25
(3800)
EIA232/V
.24
SINGLEPORT
BACK
CONNECTOR PLATE
EIA232/V.24
CONNECTOR
Figure 2-2. Modem’s Back Connector Plates
