Rear Panel - Comtech EF Data CDM-500 Installation And Operation Manual

CDM-500 Closed Network Satellite Modem
4.2

Rear Panel

All external cables are attached to connectors on the rear panel of the CDM-500. These
comprise the IEC line input connector, the Receive and Transmit IF connectors, the Data
connector, Alarms connector, Remote Control connector, and Auxiliary Serial connector.
The IEC line input connector contains the ON/OFF switch for the unit. It is also fitted
with two fuses - one each for line and neutral connections (or L1, L2, where appropriate).
These are contained within the body of the connector, behind a small plastic flap.
For 230 volt AC operation, use T0.5A, (slow-blow) 20mm fuses.
For 115 volt AC operation, use T1A fuses, (slow-blow) 20mm fuses.
FOR CONTINUED OPERATOR SAFETY, ALWAYS REPLACE THE FUSES WITH
THE CORRECT TYPE AND RATING.
The IF port connectors are both a 50 ohm BNC female type. 75 ohm cable connectors
(male) will have no problem mating with this 50 ohm type. The Data connector is a 25
pin 'D' type female (DB25-F). This connector conforms to the EIA 530 pinout, which
allows for connection of different electrical standards, including EIA-422, V.35, and
EIA-232. Please note that it is the responsibility of the user to provide the appropriate
cables to connect to this EIA 530 connector. A shielded 25 pin 'D' type provides a very
solid solution to EMC problems, unlike the sometimes used V.35 Winchester connector.
The pinout for the EIA 530 connector is provided in the next section.
Note that currently selected interface type is indicated by a small orange LED which is
located immediately above the connector. This provides aa easy visual indication to
anyone mating a connector at the rear of the unit.
The Alarms connector is a 15 pin 'D' type male (DB15-M). This provides the user with
access to the Form-C relay contacts which indicate the fault status of the unit. These are
typically connected to an external fault monitoring system, often found in satellite earth
stations. In addition, the receive I and Q demodulator samples are provided on this
connector. Connecting these signals to an oscilloscope in X,Y mode will provide the
receive signal constellation diagram, which is a useful diagnostic aid. A pin is also
provided which can mute the transmit carrier. This requires that the pin be shorted to
ground, or a TTL 'low', or an EIA-232 'high' signal be applied. The pinout details for
this connector are provided in the next section.
The Remote Control connector is a 9 pin 'D' type female (DB9-M). Access is provided to
remote control ports of the modem, both EIA-232 and EIA-485. The pinout details for
this connector are provided in the next section.
The Auxiliary Serial connector is an HE1402 3 pin header. A suitable mate for this
connector is AMP part number 281838-3, with three crimp pins, AMP part number
182734-2, also required. This is an additional EIA-232 serial port, which is only used
when the modem is part of a 1:1 pair, at the distant-end of a link, and when both units are
defined as EDMAC slaves. The pinout details for this connector are provided in the next
section.
Rev. 1.3
Physical Description
4–3