RS-449 Null Modem Cable

TABLE B-1and TABLE B-2list the signals and names for RS-499 and X.21 circuits.

TABLE B-1

RS-449 Signals

 

 

 

 

Circuit

Name

Direction

 

 

 

TxD

Transmit Data

To DCE

RxD

Receive Data

From DCE

TxC

Transmit Clock

To DCE

TxCI

Transmit Clock In

From DCE

RxC

Receive Clock

From DCE

RTS

Request to Send

To DCE

CTS

Clear to Send

From DCE

DCD

Data Carrier Detect

From DCE

DTR

Data Terminal Ready

To DCE

DSR

Data Set Ready

From DCE

SG

Signal Ground

 

 

 

 

TABLE B-2

X.21 Signals

 

 

 

 

Circuit

Name

Direction

 

 

 

G

Signal Ground

 

T

Transmit

To DCE

R

Receive

From DCE

C

Control

To DCE

I

Indication

From DCE

S

Signal Element Timing

From DCE

B

Byte Timing

From DCE

 

 

 

Appendix B Null Modem Cable Requirements 31

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Sun Microsystems Interface Adapter manual RS-449 Null Modem Cable, RS-449 Signals