Product specifications
Appendix A. I/F Modules 
76 
May 2011 
A.4 RS-530 User Data Channel Connector 
When the ETU-01A is ordered with an RS-530 interface, the physical interface is a 25-pin female 
D-Sub type connector wired in accordance with Table A-5. 
SIGNAL 
FUNCTION 
PIN CIRCUIT  DIRECTION DESCRIPTION 
Protective 
Ground 
1 Frame 
↔ 
Chassis ground. 
May be isolated from signal ground. 
Signal 
Ground 
7 AB 
↔ 
Common signal ground. 
Transmitted 
Data 
2 
14 
BA(A) 
BA(B) 
To ETU-01A  Serial digital data from DTE. 
Received 
Data 
3 
16 
BB(A) 
BB(B) 
From ETU-
01A 
Serial digital data at the output of the ETU-01A 
receiver. 
Request to 
Sent 
4 
19 
CA(A) 
CA(B) 
To ETU-01A  A ON signal to the ETU-01A when data 
transmission is desired. 
Clear to 
Sent 
5 
13 
CB(A) 
CB(B) 
From ETU-
01A 
Constantly ON. 
Data Set 
Ready 
6 
22 
CC(A) 
CC(B) 
From ETU-
01A 
Constantly ON, 
Except during test loops. 
Data 
Terminal 
Ready 
20 
23 
CD(A) 
CD(B) 
To ETU-01A  DTR not used, used for a received serial data 
rate clock input from the DTE. 
Data Carrier 
Detect 
8 
10 
CF(A) 
CF(B) 
From ETU-
01A 
Constantly ON, except when a loss of the 
received carrier signal is detected. 
External 
Transmit 
clock 
24 
11 
DA(A) 
DA(B) 
To ETU-01A  A transmitted data rate clock input from the 
data source. 
Transmit 
Clock 
15 
12 
DB(A) 
DB(B) 
From ETU-
01A 
A transmitted data rate clock for use by an 
external data source. 
Receive 
Clock 
17 
9 
DD(A) 
DD(B) 
From ETU-
01A 
A received data rate clock for use by an 
external data source. 
Remote 
Loopback 
21  RL  To ETU-01A  When on, commands ETU-01A into remote 
loopback, can disable by dipsw. 
Local 
Loopback 
18  LL  To ETU-01A  When on, commands ETU-01A into local 
loopback, can disable by dipsw. 
Test Indicator  25  TM  From ETU-
01A 
ON during any test mode 
Table A-5 RS-530 user data channel connector pin allocation 










