COURIER HIGH SPEED MODEMS
Summaries and Tables B-3
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
