Information courtesy Telebyte, Inc.
| RS-449 DB-37 Interface |
| The
EIA RS-449 standard specifies the functional and mechanical
characteristics of the interconnection between Data
Terminal Equipment (DTE) and complying to EIA electrical
interface standards RS-422 and RS-423.
 |
| Pin |
EIA
CKT |
Description |
From DCE |
To DCE |
| A |
B |
1
2 |
|
SI |
Shield
Signaling Rate Indicator |
*C |
|
4
5 |
22
23 |
SD
ST |
Send Data
Send Timing |
*T |
*D
|
6
7 |
24
25 |
RD
RS |
Receive Data
Request to Send |
*D
|
*C |
8
9 |
26
27 |
RT
CS |
Receive Timing
Clear to Send |
*T |
*C |
10
11 |
29 |
LL
DM |
Local Loopback
Data Mode |
*C |
*C
|
12
13 |
30
31 |
TR
RR |
Terminal Ready
Receiver Ready |
*C |
*C
|
14
15 |
|
RL
IC |
Remote Loopback
Incoming Call |
*C |
*C
|
16
17 |
35 |
SR
TT |
Signaling Rate Selector
Incoming Call |
|
*C
*T |
18
19 |
|
TM
SG |
Test Mode
Signal Ground |
*C
|
|
20
28 |
|
RC
IS |
Receive Common
Terminal in Service |
|
*C |
32
33 |
|
SS
SQ |
Select Standby
Signal Quality |
*C |
*C
|
34
36
37 |
|
NS
SB
SC |
New Signal
Standby Indicator
Send Common |
*C
|
*C
|
Signal Type: D = Data,
C = Control, T = Timing
Note: On the DB37 connector that is commonly used for RS449; Pins 3 and 21 are undfined
B = Return |
| RS-449 DB-9 Interface |
|
|
| Pin |
Signal |
Pin |
Signal |
| 1 |
Shield |
6 |
Receive Common |
| 2 |
Secondary Receiver Ready |
7 |
Secondary Request to Send |
| 3 |
Secondary Send Ready |
8 |
Secondary Clear to Send |
| 4 |
Secondary Receiver Data |
9 |
Send Common |
| 5 |
Signal Ground |
|
|
|