Simple RJ45 DB9 Cisco Console Cable





Introduction: Simple RJ45 DB9 Cisco Console Cable

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.

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

1 reply

glad to hear :)


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

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 ...

1 reply

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

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

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

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

1 reply

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