The Eia-232 Interface; Wiring A Db-25 To Db-9 Cable; Minimum Requirements - 3Com 56K Command Reference Manual

E-4 A E: T
PPENDIX ECHNICAL

The EIA-232 Interface

Wiring a DB-25 to
DB-9 Cable
Minimum
Requirements
I
NFORMATION
Your modem's serial port is factory set to signal according to the EIA-232
standard. See Figure A-1, Signals at your Business Modem's Serial Port.
DB-9 connectors for PCs should be wired at the computer end of the
cable as shown below.
Some computer/terminal equipment supports only a few of your
modem's EIA-232 signals. The minimum required for your modem to
operate asynchronously follows:
DB-25
Pin
2
3
7
20
DB-9 Supports this signal
Pin Function
3 Transmitted Data
2 Received Data
5 Signal Ground
4 Data Terminal Ready