Reference Guide | Cable Tester

Cisco Console Cable (USB to RJ45 Serial RS232)

A Cisco Console Cable is a type of cable that is used to connect the console port of Cisco equipment to a computer. The console port is a serial port that provides access to the command-line interface (CLI) of the device for administrative purposes. It is typically used for configuring, managing, and troubleshooting Cisco routers, switches, and other network devices.

RJ45 Console Cable History

The console cable started off with this old RS232 to RJ45 cable. Often seen as a light blue color cable.

The cable is typically an RS232 cable with a 9-pin serial connector (d-sub09) on one end and an RJ45 connector on the other end. The RJ-45 connector is used to connect to the console port on the Cisco device, while the RS232 connector is used to connect to a computer.

RS232 serial connector was commonly used a decade or more ago. RS232 port is obsolete mostly from modern computers these days. It is replaced by the USB version which is much more popular.

Check out this page for the pin out of RS232 to RJ45 console cable.

USB to RJ45 Console Cable

A more popular Cisco Console Cable will be the USB to RJ45 console cable. USB (type A) is a more popular interface on a modern computers.

Simple plug-and-play. It is essentially a USB to RS232 converter electronics built into the cable.

Modern USB (type-A) to RJ45 console cable.

USB-C to RJ45 Console Cable

A newer type of cable will be the USB-C to RJ45 console cable. It is base on a newer USB 3.0 standard. USB-C (type C) standard is getting more popular with small mobile devices. USB-C connector is much smaller in size compared to the USB (type A).

This cable is very useful for connecting the console via your portable mobile phone. Most phones, tablets, and laptops now come with only USB-C ports.

Terminal Software for Console Cable

The Cisco Console Cable is an important tool for network administrators, as it allows them to configure and troubleshoot Cisco network devices. The cable is commonly used in combination with terminal emulation software, such as PuTTY, that provides a terminal window for communicating with the device through the console port.

Serial Communication Settings

Typical communication baud rate setup for a serial console cable.

Baudrate: 9600bps
Data bit: 8 bits
Stop bit: 1 bit
Parity: None
No Hardware Handshaking

There are many other terminal emulation software. The following are some of the most popular free terminal software.

Terminal Software for PC (Personal Computer)

MobaXterm
Docklight
Window’s HyperTerminal console
Cmder
Zoc
ConEmu
Mintty
MobaXterm
Babun
PuTTY
KiTTY
Xshell
ConsoleZ
Console2
z/Scope
Hyper
FireCMD
Terminus

Serial Terminal using MobaXterm serial terminal software for PC

Terminal Software for Andriod Mobile Phone

Serial USB Terminal

You can use USB-C to RJ45 console cable to connect the Cisco equipment/devices to connect to your mobile phone.

For more illustration of using this console terminal, check out this guide for the Serial USB Terminal app.

Mobile phone and console cables are portable and more convenient to bring along to the site for troubleshooting or configuration.

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RS232 Cable Tester

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(Step 1) Setup RS232 Connectors.

Find a mating connector for your RS232 Cable.

The mating connectors can come from an RS232 cable. Cut it in half and strip the wire of the mating connectors. Screw down the striped bare end of the wires to the screw terminal (green plug).

The screw terminal is to be plugged into the CCT-01 Cable Tester.

d-sub 09 female connector setup
for RS232 cable testing.

Screw each of the wire onto the screw terminal (green plug).

You can screw the wire in in any order onto the screw terminal.

d-sub 09 male connector setup
for RS232 cable testing.

(Step 2) Learn master cable’s connection.

Plug in your mating connector to the CCT-01 Cable Continuity Tester.

Plug in your original master RS232 cable onto the mating connector.

Press LEARN button to learn the wiring connection of your master cable.

(Step 3) Test RS232 cables

Unplug the master cable aside. You no longer need this master RS232 cable. The connection from this master RS232 cable is learned and memorized by this cable tester.

Plug in the RS232 cable that you want to test. Press the “Start Test”.

A green LED indicates with beep tones indicates that the RS232 cable has passed the test. The connection of this RS232 cable is the same as the master cable that was learned earlier.

A red LED indicates that the RS232 cable tested is different from your master cable.

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RJ45 Pinout

A quick wiring reference guide to the network cable using RS45 connector (or the 8P8C modular plug).

Pinout

The following is the most common wiring color scheme (T568B) for Ethernet network cable.

T568A vs T568B … What is the difference?

T568B wiring color code scheme is the most commonly used standard. The difference between T568B and T568A is in the color code scheme. Orange color twisted pair is swap with the green pair. If you are doing a Straight Cable for your network connection, it doesn’t make any difference using T568B or T568A color code scheme.

Difference between T568B and T568A wiring color scheme.

Reference: https://www.truecable.com/blogs/cable-academy/t568a-vs-t568b#

Why is it important to follow the wiring color scheme?

It is important to follow the color scheme as it will have impact on the data communication speed. TX+ TX- pair and RX+ RX- pair has to be in the same twisted wired pair.

The data communication is using differential signal transmission method. Differential signalling travels further down the line and can support higher data transmission speed. It is important to twist this pair of wires throughout the transmission line, as twisted pair wire have minimum gap between the wire. Gap allow interference from nearby surrounding noise, or adjacent signal wires. This interference result in signal/data corruption and hence a low data throughput rate across the cable. It you do not wire the TX and RX wire in twisted pairs, you will observe a significant drop in your network speed to as low as 10Mbps or lesser. If you are interested to learn more about this topic, you can study books relating to electromagnetic wave, radio frequency transmission theory.

In the T568B wiring scheme, TX+ TX- are the orange/white orange wire pairs, and RX+ RX- are the green/white green wire pairs.

Crossover Network Cable

The crossover cable means that on one end of the cable is using the T568B wiring color scheme, while the other end uses T568A. This means that the TX signal transmit from one end is connected to the RX on the receiver end.

Cross network cable is seldom needed these days. They are use when a computer need a direct communication connection to another computer system, instead of to the hub. Most of the network interface circuitry is able to do automatic line switching internally. This is why we normally only deal with straight network cable these days. There is no longer a need to be concern with whether to use a cross cable or a straight cable.

Straight network cable has the same wiring color scheme on both end of the cable. It can be both cable end with T568B color code, or both end using T568A color code.

Reference: https://www.practicalnetworking.net/stand-alone/ethernet-wiring/#why_crossover

Ethernet Pinout Signal

The following table is the physical signal of the RJ45 pinout from a computer system (from PC side). Pin 1 and 2 are transmitting data out from the computer to a Hub.

Physical signal of the T568B wiring color scheme.

Reference: https://en.wikipedia.org/wiki/ANSI/TIA-568

Data flow between PC and Hub

Straight or Crossover wiring between PC and Hub

The data flow connection between a PC and a Hub is crossed internally at their RJ45 socket pin connection. A straight network cable is used for connecting between these 2 devices.

When a PC needs to be connected to a PC, or a Hub to another Hub, a cross cable is required to ensure that the data is transmitted on one end, while the other end of the PC gets to receive the data.

Cross cable is seldom needed these days as the Ethernet hardware today can automatic switch the TX RX internally within the hardware level. User does not need to be concern with using a cross or straight network cable.

Reference: https://incentre.net/ethernet-cable-color-coding-diagram/

Legend (CAT network cable)

Pair 1 – Blue + Blue/White
Pair 2 – Orange + Orange/White
Pair 3 – Green + Green/White
Pair 4 – Brown + Brown/White

Tool to make your work easier

8P8C Plug

This is a new type of RJ45 modular plug that allows wire through the tip of the plug. This RJ45 plug design makes it much easier to insert the wire. There is no need to trim the 8x wires to proper length first before inserting them into the RJ45 plug for crimping.

These new type of RJ45 plug connector is also made of more elastic material. The quick release lever catch is more flexible and does not break so easily.

You will need the following crimping tool to crimp and trim the wires in a single clamp action.

Crimping Tool

This is a small portable and handy crimping tool for RJ45 connector. It can crimp 8P8C modular plug, as well as trimming the network CAT wires all in a single action.

Network Access Tester

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Network Cable Tester

This is a simple network cable tester. Checks if the network cable is probably crimped, or if they are still usable.

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RJ45 Plug Pin no.	T568B color scheme	10/100 BASE-T	1000BASE-T
1	orange/white	TX+	DA+
2	orange	TX-	DA-
3	green/white	RX+	DB+
4	blue	not used	DC-
5	blue/white	not used	DC+
6	green	RX-	DB-
7	brown/white	not used	DD+
8	brown	not used	DD-