Comtech EF Data CDM-570 - Manual (Page 68)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Rear Panel Connectors and Pinouts MN/CDM570L.IOM
3–4
3.3 IF Connections
3.3.1 Data Interface Connector, DB-25F
The 25-pin ‘D’ type female (DB-25F) Data Interface connector
conducts data input and output breakout panel, or protection switch.
This connector conforms to the EIA-530 pinout, which allows for
connection of different electrical standards, including EIA-422, V.35,
and EIA-232. A shielded DB-25F connector provides a very solid solution to EMC problems,
unlike the sometimes-used V.35 Winchester connector.
THE MODEM IS ALWAYS ASSUMED TO BE DCE
Table 3-2. Data Interface Connector Pin Assignments
Pin #
Generic Signal
Description
Direction
EIA-422
EIA-530
V.35 EIA-232 Circuit #
2 Transmit Data A DTE to Modem SD A SD A BA 103
14 Transmit Data B DTE to Modem SD B SD B - 103
24 Transmit Clock A DTE to Modem TT A SCTE A DA 113
11 Transmit Clock B DTE to Modem TT B SCTE B - 113
15 Internal Tx Clock A Modem to DTE ST A SCT A DB 114
12 Internal Tx Clock B Modem to DTE ST B SCT B - 114
3 Receive Data A Modem to DTE RD A RD A BB 104
16 Receive Data B Modem to DTE RD B RD B - 104
17 Receive Clock A Modem to DTE RT A SCR A DD 115
9 Receive Clock B Modem to DTE RT B SCR B - 115
8 Receiver Ready A Modem to DTE RR A RLSD CF 109
10 Receiver Ready B Modem to DTE RR B - - 109
5 Clear to Send A * Modem to DTE CS A CTS CB 106
13 Clear to Send B * Modem to DTE CS B - - 106
4 Request to Send A * DTE to Modem RS A RTS CA 105
19 Request to Send B * DTE to Modem RS B - - 105
6 Data Set Ready A * Modem to DTE DM A DSR CC 107
22 Data Set Ready B * Modem to DTE DM B - - 107
7 Signal Ground - SG SG AB 102
1 Shield - Shield FG AN 101
1. When the rear-panel switch marked “1:N Switch” is in the OFF position, 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 switch marked “1:N Switch” is in the ON position, the highlighted signals, plus
pins 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 EF Data 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.