Rockwell Automation 1766-Lxxxx MicroLogix 1400 Programmable Controllers User Manual - Manual (Page 81)

Rockwell Automation Publication 1766-UM001H-EN-P - May 2014 67
Communication Connections Chapter 4
Constructing Your Own Null Modem Cable
If you construct your own null modem cable, the maximum cable length is
15.24m (50 ft) with a 25-pin or 9-pin connector. Refer to the following typical
pinout:
Optical Isolator Modem
9-Pin 25-Pin 9-Pin
3 TXD TXD 2 3
2 RXD RXD 3 2
5 GND GND 7 5
1 CD CD 8 1
4 DTR DTR 20 4
6 DSR DSR 6 6
8 CTS CTS 5 8
7 RTS RTS 4 7