CopperOptics 150-1619-11, Technical Practice, Page: 19 / 52

950-719-111-03, Revision 03 Overview
PCS-719 List 1A June 29, 2000 13
Network Interface
The COT shelf supports RS-232 X.25 interfaces through a backplane-mounted DB25 connector. The rear
backplane DB-25 is a female connector wired as a Data Terminal Equipment (DTE) interface. The signals and pin
assignments for this connector are listed in
Table 18 . This connector is for communication with a DCE device such
as a modem. Figure 4 shows the cable connections between the backplane connector and a DCE DB-25 connector.
To connect to a DTE device from the backplane connector, a null modem cable is required. Figure 5 shows the
wiring for the required null modem cable to a DB-9 and DB-25 connector. This feature requires a PMU installed
in the COT shelf. Refer to the PMU documentation for additional information on this interface.
Figure 4. Modem Connection for PCS-719 Backplane
Table 18. PCS-719 Backplane DB-25 Connector Pinouts
DB-25 Pin Signal
2 Transmitted Data
3 Received Data
8 Carrier Detect
7 Signal Common
20 Data Terminal Ready