L131: Eia-422, Dc-37 With Control Signals; Table 3. Eia-449 Interface Dc-37 Pin Assignments - Canoga Perkins 2370 User Manual

3.3

L131: EIA-422, DC-37 With Control Signals

The L131 ELIM for EIA-449 is electrically compatible with the EIA-422 specifications for clock and
data and with EIA-423 for control signals. It uses a female DC-37 connector; Table 3 lists the pinout.
SD, RD, ST, RT and TT provide the primary data and clock signals. ST provides the transmit clock
reference for Internal and Slave modes. RT provides the clock for the received data. TT provides the
transmit clock for External mode.
The control signal outputs are unbalanced drivers and the B-leads of the differential control signal
outputs are tied to signal ground to comply with EIA-422. None of the control leads interact with the
data transmission, but they do comply with DTE interface requirements. Most of the control leads are
end-to-end signal channels that can conform to EIA-449 interface standards..
The EIA-449 interface includes three end-to-end control leads; input to output:
•
RS to RR
•
TR to IC
•
NS to SQ
DM and TM provide local status and follow the RS-449 functions. DM typically indicates that the
modem is ready to receive data. LL and RL are loopback control inputs and follow the software
setting, unless a 2370 in a Model 1040 is in hardware mode and the function switch on the enclosure
is set for loopback, then LL and RL are ignored. For details on the software and loopback tests, see
Sections 4.12 and 5.1.

Table 3. EIA-449 Interface DC-37 Pin Assignments

DC-37 Pin EIA-449 Signal
1 SHLD
3/21 not used
4/22 SD
5/23 ST
6/24 RD
7/25 RS
8/26 RT
9/27 CS
10 LL
11/29 DM
12/30 TR
13/31 RR
14 RL
15 IC
17/35 TT
EdgeAccess® Universal Chassis System
Function
Shield (Ground)
Send Data
Send Timing
Receive Data
Request to Send
Receive Timing
Clear to Send
Local Loopback
Data Mode
Terminal Ready
Receiver Ready
Remote Loopback
Incoming Call
Terminal Timing
Model 2370 Model User Manual
Direction
In
Out
Out
In
Out
Out
In
Out
In
Out
In
Control
In
3-5