COURIER HIGH SPEED MODEMS

PIN ASSIGNMENTS

The entire standard covers many more functions than are used in most data communications applications. Pin assignments are factory set in the Courier to match the standard DB-25 assign- ments in the following table. DB-9 connectors for AT- compatible computers should be wired at the computer end of the cable as shown in the DB-9 column. If you're using an Apple computer, we strongly recommend that you purchase a Hardware Handshaking cable to get the highest possible reliability performance.

 

 

 

 

Signal Flow

DB-25 DB-9

Circuit

Function

Computer

 

 

 

 

Modem

1

_

AA

Chassis Ground

both directions

2

3

BA

Transmitted Data

to modem

3

2

BB

Received Data

to computer

4

7

CA

Request to Send

to modem

5

8

CB

Clear to Send

to computer

6

6

CC

Data Set Ready

to computer

7

5

AB

Signal Ground

both directions

8

1

CF

Carrier Detect

to computer

12

_

SCF

Speed Indicate

to computer

15

_

DB

Synchronous TX* Timing

to computer

17

_

DD

Synchronous RX* Timing

to computer

20

4

CD

Data Terminal Ready

to modem

22

9

CE

Ring Indicate

to computer

24

_

DA

Synchronous TX* Timing

to modem

* Indicates Transmitter (TX) or Receiver (RX)

Table B.1RS-232 Interface Pin Definitions

Summaries and Tables B-3

Page 97
Image 97
USRobotics V.34 user manual Table B.1⎯RS-232 Interface Pin Definitions, DB-25 DB-9 Circuit Function Computer ⎯ Modem