APPENDIX A: Interface Pinouts
49
Appendix A: Interface Pinouts
A.1 Main (Composite) Channel Interface
The stat mux main (composite) channel interface is configured as a synchronous DTE RS-232 interface, with a
male DB25 connector. Table A-1 lists the pinouts.
Table A-1. Main (composite) channel connector.
CCITT V.24
EIA RS-232C
Pin
Signal
Description
Circuit Number Line
Name
101
AA
1
Protective Ground
Chassis ground (may be isolated
from signal ground or connected to
it—refer to
Section 3.3
102
AB
7
Signal Ground
Common signal and DC power
supply ground
103
BA
2
Transmit Data
Serial digital transmit data from
the stat mux
104
BB
3
Receive Data
Receive data from modem
105
CA
4
Request to Send
Continuous positive level from
stat mux
109
CF
8
Data Carrier Detect
Data carrier detect indication from
modem
114
DB
15
Transmitter Signal
Transmit clock from modem
Element Timing
115
DD
17
Receiver Signal
Receive clock from modem
Element Timing
141
—
18
Loop 3 Test Command
Control signal from stat mux:
positive level commands the
modem to enter analog loopback
