Using cables to connect the motors to the brick Pro Preview

We will learn how to connect and disconnect LEGO cables and on which ports exactly to connect the motors.

  • #355
  • 04 Feb 2017
  • 3:53

A cable is used to connect the Brick with the motors. In the future you will connect your sensors with cables, too.
The cables transport electrical power and electrical command signals from the Brick to the motors and the sensors.

How to connect and disconnect them properly

Make sure to hear the click sound when pushing the cable in the port. This way the cable is fixed in the port and will not fall off on its own.
In order to disconnect it, just press lightly on the transparent plastic part of the jack that comes out of the port.

Cable length

There are three types of cables by length - use the optimal length for each situation. Use а short cable when the motor/sensor is close and а medium or long cable otherwise.

Default motor ports

Always respect the default ports for each motor and sensor.
Large motors must be connected to ports B and C.


The Lego Mindstorms EV3 comes with a number of different cables that are used to connect the brick to the motors and to the other sensors. And in this video we'll look at some of the features of the cables.

First, after you have your robot constructed the first EasyBot robot, you have a construction that looks like this and now to make it work you must connect the motors to the brick. If you have sensors you may also connect the sensors to the brick. But there must be some kind of a connection between the brick, the motors, the sensors, and you make this connection with a cable. You have a port on the brick and you add the cable to the port. And when you push on the cable you can hear a small click. And it's very important to hear this, so that you have a good contact between the port and the cable. Then when you remove the cable just don't pull on the cable because it's locked. And you must press right here

and then you can easily remove the cable. Again, push with click and then remove in this way. And this is the same place for the other end of the cable. So, I'll connect the cable to the brick and now I have a motor and I'll just add the other end of the cable to the motor. It's a very common mistake not to push the cable and it won't click and from there you don't have a good contact and from there your program is not working because the brick can't communicate with the motor. And you also have different cables with different length. You can see this cable and it's longer than the previous one.

So, always try to use the cables with appropriate length. For example, if you just have to connect the motor to the brick and the motor is not that far away from the brick you can use the shortest cable and you can save the longest cable for some of the attachments. That's the basic thing about the cables. You have four different ports on which you can connect the motors. And you can connect the motor on port A and on port D. Or you can connect them on A and B, or on C and D. You can connect them in a number of different ways. There's a default way that we in the course are going to use and that most of the Lego communities are using and even the software is using this default connection. You always have the left motor connected on port B and you always have the right motor connected on port C. That's not an requirement that's a convention and that's an easy way to communicate and to be faster in the course. Just to have a default connection so that we can know that the motors are always connected on port B and port C.

Courses and lessons with this Tutorial

This Tutorial is used in the following courses and lessons

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Image for Lesson 1
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Image for Level A1. Introduction. Robotics with LEGO
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