EIA-232 Cabling Diagrams
28 IOLAN Device Server User’s Guide, Version 1.0
PC DB9 Connector
The following diagram shows how the null modem cable should be configured when connecting to a
DB9 PC.
2 (TxD) 2 (RxD)
3 (RxD) 3 (TxD)
4 (RTS) 8 (CTS)
5 (CTS) 7 (RTS)
6 (DSR) 4 (DTR)
7 (GND) 5 (GND)
20 (DTR) 6 (DSR)
Modem DB9 Connector
The following diagram shows how the cable should be configured when connecting to a DB9
Modem.
2 (TxD) 3 (RxD)
3 (RxD) 2 (TxD)
4 (RTS) 7 (CTS)
5 (CTS) 8 (RTS)
6 (DSR) 6 (DSR)
7 (GND) 5 (GND)
8 (DCD) 1 (DCD)
20 (DTR) 4 (DTR)
IOLAN DS1
DB25 (DTE)
PC DB9
(DTE)
IOLAN DS1
DB25 (DTE)
Modem DB9
(DCE)