CDM-625 Advanced Satellite Modem
Revision 1
Rear Panel Connector Pinouts
MN-0000036 (Ref MN/CDM625.IOM)
3.3
Terrestrial Data Connections
3.3.1
Data Interface Connector, DB-25F
The Data Interface connector is a 25-pin, Type ‘D’ female interface that
conducts data input and output signals to and from the modem, and
connects to customer’s terrestrial equipment, breakout panel, or
protection switch. Refer to
Table 3-2
for pin assignments.
Table 3-2. Data Interface Connector Pin Assignments
Pin #
Generic Signal
Description
Direction
EIA-422
EIA 530
V.35
HSSI
LVDS
Circuit #
2
Transmit Data A
DTE to Modem
SD A
SD A
SD A
SD A
103
14
Transmit Data B
DTE to Modem
SD B
SD B
SD B
SD B
103
24
Transmit Clock A
DTE to Modem
TT A
SCTE A
TT A
TT A
113
11
Transmit Clock B
DTE to Modem
TT B
SCTE B
TT B
TT B
113
15
Internal Transmit
Clock A
Modem to DTE
ST A
SCT A
ST A
ST A
114
12
Internal Transmit
Clock B
Modem to DTE
ST B
SCT B
ST B
ST B
114
3
Receive Data A
Modem to DTE
RD A
RD A
RD A
RD A
104
16
Receive Data B
Modem to DTE
RD B
RD B
RD B
RD B
104
17
Receive Clock A
Modem to DTE
RT A
SCR A
RT A
RT A
115
9
Receive Clock B
Modem to DTE
RT B
SCR B
RT B
RT B
115
8
Receiver Ready A
Modem to DTE
RR A
RLSD
CA A
RR A
109
10
Receiver Ready B
Modem to DTE
RR B
-
CA B
RR B
109
5
Clear to Send A *
Modem to DTE
CS A
CTS
-
-
106
13
Clear to Send B *
Modem to DTE
CS B
-
-
-
106
4
Request to Send A *
DTE to Modem
RS A
RTS
TA A
-
105
19
Request to Send B *
DTE to Modem
RS B
-
TA B
-
105
6
Data Set Ready A
Modem to DTE
DM A
DSR
-
-
-
22
Data Set Ready B
Modem to DTE
DM B
-
-
-
-
7 Signal
Ground
-
SG SG SG SG 102
1 Shield
- Shield
FG
Shield
Shield
101
Notes:
1.
When the rear-panel LED marked “
1:N Active!
” is
OFF
, all of the signals shown above are available and functional.
In addition, pins not shown are not connected, and therefore no damage will occur if other signals are connected to
the additional pins.
2.
When the rear-panel LED marked “
1:N Active!
” is
ON
, the signals shown highlighted are no longer available.
Furthermore, pins 6, 18, 20, 21, 22, 23 and 25 are reserved for use by the 1:N system.
DO NOT
connect signals to
any of these pins in this mode. Certain pins have DC voltages present that may damage equipment other than a
Comtech redundancy switch.
3.
For X.21 operation, use the EIA-422 pins, but ignore Receive Clock if the Modem is DTE, and ignore Transmit
clocks if the Modem is DCE.
4.
For IDR operation using G.703, this primary interface becomes the 8 kbps EIA-422 overhead channel.
3–4
