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.

RJ45 pinout (Network cable wiring)
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.

RJ45 Plug Pin no.T568B color scheme10/100 BASE-T1000BASE-T
1 orange/whiteTX+DA+
2 orangeTX-DA-
3 green/whiteRX+DB+
4 bluenot usedDC-
5 blue/whitenot usedDC+
6 greenRX-DB-
7 brown/whitenot usedDD+
8 brownnot usedDD-
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

New RJ45 modular plug (8P8C)

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

RJ45 pins 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

This network access tester helps to test the network connectivity of your physical network point directly with your mobile phone. Quick and portable tool to check for network connectivity on site.

Click here for more other Network Access Tester tools.

Network Cable Tester

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

Click here for more information on this Network Cable Tester.

MDB connector Pin Out

MDB pin out

Introduction to MDB

MDB is a communication standard used in the vending machines industry to inter-link numerous devices used in a vending system. It is one of the common standardised vending used around the world today. You can typically find this MDB connector connection in the following type of machines.

  • Cold/Hot Drinks Vending Machines
  • Toy Catchers Machines
  • Coffee Dispenser Machines
  • Packet Snacks Vending Machines
  • Hot Food Baking Machines

Another vending standard is VCCS. It is adopted by the vending industry in Japan. Vending machine from Japan manufacturer typically uses VCCS instead of MDB interface standard.

MDB Connector details

Peripheral Connector

Molex Mini-Fit Jr 5569 Series, 6 ways (buy part number: 39-30-1060)

Master (VMC) Connector

  • Molex Mini-Fit Jr 5557 Series, 6 ways (part number: 39-01-2060)
  • Molex Insert pins – for 28AWG to 22AWG (part number: 39-00-0209)

Alternative connectors available

  • ULTICOMP (MC34509)
  • TE CONNECTIVITY (794954-6, 15

Tools accessories

  • MOLEX 11-03-0044 Extraction Tool for Mini-Fit Jr Crimp Terminals

MDB Communication Protocol Documentation

Also known as MDB ICP (Multi Drop Bus, Internal Communication Protocol). The following are the detail containing the communication protocol standard used on the MDB connection interface.

Serial Communication Configuration: 9600bps NRZ, 1 Start Bit, 8 Data Bits, 1 Stop Bit, 1 Mode Bit, no hardware handshaking.

The mode bit is a special 9th bit in the communication protocol, acting as a indicator to finish up an on-going communication.

MDB Interface Circuit & Signal

The MDB interface is in a pull-up pull-down voltage and open-collector configuration. This allows interface to other devices without too much affected by the voltage system that the other devices is deployed with.

MDB interface circuit & signal

The signalling is pretty similar to the serial communication UART. You can actually implement MDB using the UART from microcontroller. MDB protocol has a mode bit which is using the 9th bit of the UART serial protocol standard.

Cable Wire Size and Current Capacity Rating Guide

This is a general cable wire size guide to help you choose the correct wire size for your electrical project.

Choosing a thicker wire provides higher current carrying capacity. It is safer to use thicker wire to conduct the current, but thicker wire is going to cost more. This guides provides you a gauge to select the most appropriate cable size.

*** Important Notes: The variety of cable brands varies in quality. The cable conducting and insulation jacket material do have an impact of the amount of ampere current that a wire can conduct. The cable length and temperature of the conducting environment also plays a part. The following wire size and current is only an estimate for a quick reference guide when selecting your cable size. It is important to check on the datasheet of the cable directly from the manufacturer.

Wire Size and Current Rating Table Guide

Projected Maximum
Operating Current
Wire Size
(AWG)
Copper Wire
Diameter Ø
Cross-sectional
Area
Current Capacity
0.1A
0.3A
0.5A30AWG
Wire Wrapping wire
0.3mm0.05mm20.8A
1A28AWG0.36mm0.08mm21.25A
2A27AWG
3A26AWG0.46mm0.14mm23.5A
5A24AWG
CAT5e Network Cable
0.61mm0.2mm25A
22AWG0.78mm0.33mm28.73A
10A21AWG
20AWG0.92mm0.5mm213.87A
25A17AWG1.34mm1.06mm229.2A
16AWG1.31mm2 (closest 1.5mm2)
50A14AWG
Electrical Wire
1.78mm2.07mm2 (closest 2.5mm2)55.6A
12AWG
Electrical Wire
about 4mm2
10AWG
Electrical Wire
about 6mm2