2 rs-232 option – Comtech EF Data SMS-758 User Manual
Page 83
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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
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