363-206-285
Technical Specifications
10-58 Issue 3 June 2001
Operations Interfaces 10
This section presents the operation interfaces that are required to support
technician access to the system and allow alarms and status information
generated by the system to be reported. The local operation interfaces include the
CIT interface, the user panel, and the equipment indicators. The DDM-2000 OC-3
Multiplexer supports office alarms, parallel telemetry, user-definable
miscellaneous discretes, serial (TBOS) telemetry interfaces, and TL1/X.25.
Craft Interface Terminal (CIT) 10
The system provides two EIA-232-D compatible CIT interfaces — a front access
interface, configured as data communications equipment (DCE), and a rear
access CIT interface, configured as data terminal equipment (DTE), to allow a
permanent modem connection without requiring a null modem. A null modem is
required to connect an ASCII terminal to the DTE interface or a modem to the
DCE interface. The CIT interfaces provide data rates of 300, 1200, 2400, 4800,
9600, and 19,200 baud.
Both CIT interfaces operate full duplex using 1 start bit, 8 data bits, and 1 stop bit.
Table 10-24 describes the pins supported on the CIT interfaces.
Table 10-24. CIT Interface Pin Connections
EIA-232-D Pin Front Access CIT (DCE) Rear Access CIT (DTE)
Pin 2 — Circuit BA
Transmitted Data
carries data from
terminal to DDM-2000 OC-3
carries data from DDM-2000 OC-3
to modem or terminal
Pin 3 — Circuit BB
Received Data
carries data from
DDM-2000 OC-3 to terminal
carries data from modem or
terminal to DDM-2000 OC-3
Pin 7 — Circuit AB
Signal Ground
signal ground signal ground
Pin 8 — Circuit CF
Received Line
Signal Detector
not used indicates to DDM-2000 OC-3 that
modem or terminal is connected
Pin 20 — Circuit CD
DTE Ready
indicates to DDM-2000 OC-3
that modem or terminal is
connected
indicates to modem or terminal that
DDM-2000 OC-3 is connected (always
ON when SYSCTL is powered)
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