RJ45 Console cable to DB-9 Serial

Network devices with RJ45 console ports typically follow the Cisco pin out. The pinout below shows a null modem wiring between the RJ45 and a Serial DB9 female connector. This is known to work on Cisco, Juniper, Zyxel and Ubiquiti Edge series devices with RJ45 console ports. If you are using UTP network cable then the colour coding for the two standards EIA 568A and EIA 568B is shown.


RJ45 Pin
Number
RJ45 Pin
Name
DB9 Pin
Number
DB9 Pin
Name
Description TIA/EIA
568A
TIA/EIA
568B
1 RTS

8

CTS Request To Send -> Clear To Send Orange/White Green/White
2 DTR 6 DSR Data Terminal Ready -> Data Set Ready Orange Green
3 TXD 2 RXD Transmit Data -> Receive Data Green/White Orange/White
4 GND 5 GND (tie pins 4/5 on RJ45 to Pin 5 on DB9) Blue Blue
5 GND 5 GND Ground Blue/White Blue/White
6 RXD 3 TXD Receive Data <- Transmit Data Green Orange
7 DSR 4 DTR Data Set Ready -> Data Terminal Ready Brown/White Brown/White
8 CTS 7 RTS Clear To Send <- Request to Send Brown Brown

A simplified version of this NULL modem cable would only connect RXD, TXD and GND (this sacrifices flow control for simplicity). For other variations on null modem cables see this page

RJ45 Pin
Number
RJ45 Pin
Name
DB9 Pin
Number
DB9 Pin
Name
Description TIA/EIA
568A
TIA/EIA
568B
3 TXD 2 RXD Transmit Data -> Receive Data Green/White Orange/White
5 GND 5 GND Ground Blue/White Blue/White
6 RXD 3 TXD Receive Data <- Transmit Data Green Orange