Simple RJ45 DB9 Cisco Console Cable




Introduction: Simple RJ45 DB9 Cisco Console Cable

About: Learning on the fly and finding solutions for my issues

Hello everyone,

I just bought my first cisco router (2610) and, in order to learn about it I decide to start a blog. The idea its to provide a step-by-step from nothing to something that can be useful in a SOHO environment. The blog still in the very early steps, but it will be the experience of my interaction with my cisco router. here the URL:

I bought my router online (craigslist) and it came without the console cable. Looking around I found many articles talking about build your own cable but none as simple and easy as I wanted to be. Many articles describe adapter, mini cables, etc, and I was just looking for some straight, simple, easy do understand instructions.

This instructable is my attempt to provide the level of information I was looking for myself.

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Step 1: Getting Started - Bill of Material

First we start with the parts:
  • Cat5e cable (mine has 6ft.);
  • 1 RJ45 Connector;
  • 1 DB9 Connector;
  • Crimp tool;
  • Soldering Iron.

Step 2: Crimping the RJ45 Connector

Lets start crimping the RJ45 connector. I personally use  TIA/EIA 568A wiring diagram to all my cables, so I will continue doing so:

If you never crimped a RJ45 before, please refer to this video:

(credit: video from

There are many videos/sites showing how to crimp.

Just make sure you follow, in this case, TIA/EIA 568A wiring diagram

Step 3: Connectiing the DB9

The following diagram shows how each cable, by color, should be connected:

CAT5                                DB9 Pin
Green-White                         8
Green                                     6
Orange-White                       2
Blue                                        5
Blue-White                            5
Orange                                   3
Brown-White                         4
Brown                                     7

The Blue/White and Blue must both connect to pin 5 on the DB9. Pins 1 and 9 are not connected.

This is the RS232 Pins assignment (for reference)

Pin 1 - Received Line Signal Detector (Data Carrier Detect)
Pin 2 - Received Data
Pin 3 - Transmit Data
Pin 4 - Data Terminal Ready
Pin 5 - Signal Ground
Pin 6 - Data Set Ready
Pin 7 - Request To Send
Pin 8 - Clear To Send
Pin 9 - Ring Indicator

Step 4: Done

That's it. 

Cant be simpler than that.



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11 Discussions


1 year ago on Introduction

Thanks for this info. I been doing these cables for class and all work nicely. Thanks again


Reply 1 year ago

glad to hear :)

LB zim1
LB zim1

3 years ago


I also have a point of sale workstation that doesnt have serial port for DB9 so that i can connect an Epson printer, how do i convert a normal fly lead such that one end is RJ45 and the other is DB9 male? Please help


4 years ago

If you need to make one of these and only have male DB9 connectors on hand, as opposed to the female shown above, and a null modem cable then you need to use this pin assignment instead:

CAT5 -> DB9 Pin
Green-White -> 7

Green -> 4

Orange-White -> 3

Blue -> 5

Blue-White -> 5

Orange -> 2

Brown-White -> 1

Brown -> 8

You would connect this cable to the null model cable and then connect the null model cable to your computer.


Why on Earth would you use a RJ45 as a serial connector, instead of the standard DB9 ? Another Cisco brilliance at its finest ...


Reply 4 years ago on Introduction

So you can patch it into a patch panel and send it away from the rack. Granted, you could do this with 2x DB9/RJ45 cables but this is neater. Lots of other manufacturers use an RJ45 console port, RAD, LOOP, Verilink.etc


5 years ago on Introduction

I just did it and it works perfectly! Thanks for the instructions.


7 years ago on Step 4

Soldered this cable, thanks very much. But the reception from the device is, and not a command from the keyboard is not received.


9 years ago on Introduction

hi Mr.pcapelo, very interesting i'ble as i'm doin my CCNA and a friend of mine was askin me to make a console cable for his 2500 router for practicing. Thanks to you now i can clear my doubts. just 1 doubt regarding step 3 of your i'ble, you have mentioned DB9 pin 5 twice, i'm sure there's a typo there. cud you please clear my doubt??? Once again, GR8 i'ble God Bless


Reply 9 years ago on Introduction

Hi, thank you for your message. No its not a typo. you have to connect cables blue and blue-white to pin 5. I found this info online, use to build my cable and everything works fine, so i decide to keep the pinage same. thank you again PC