User Manual Manual

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
5GND GND7 5
1CD CD8 1
4DTR DTR204
6 DSR DSR 6 6
8 CTS CTS 5 8
7 RTS RTS 4 7