Comtech EF Data SMS-758 - Manual (Page 83)

SMS-758 Modem Protection Switch Theory of Operation
MN/SMS758 Rev. 3 4–23
4.6.3.2.2 RS-232 Option
When the switch is in the RS-232 position, the 25-pin D connector now provides the
interface for RS-232 mode of operation. Screw locks are provided for mechanical
security of the mating connector.
Pin # Signal Name Direction Circuit
1 Ground AA
7 Ground AB
2 Transmitted Data IN BA
15 Transmission Signal Element Timing OUT DB
3 Received Data OUT BB
4 Request to Send IN CA
17 Receiver Signal Element Timing OUT DD
5 Clear to Send OUT CB
18 Carrier Present OUT
6 Data Set Ready OUT CC
8 Receive Line Signal Detect OUT CF
9 External Reference Clock IN
11 Demodulator Fault
24 Transmit Signal Element Timing IN DA
25 Modulator Fault
10, 12, 13,
14, 16, 19,
21, 22, 23 No connection