No EtherCAT connection

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This is one of the most common errors. It can be caused by multiple factors. Most common are listed below.

Emergency stop button is pressed

If the emergency stop functionality is implemented, check if your stop button is not pressed.

Hard stop jumper is disconnected

Hard stop jumper is used to bypass unused stop functionality. Check if its not removed or disconnected. How to find a jumper

Soft stop jumper is disconnected

Soft stop functionality disable all EtherCAT communication. Check if the jumper is not removed or disconnected. Soft Stop

Program can not access etherCAT

See Execute as a root

You are using wrong etherCAT port

After a new installation of the operating system the device NAME of the network interface, on which the etherCAT devices are connected, can be different from the one stated in the configuration file. Normally Linux assigns a name like eth0, eth1, etc… The internal PC of the youBot for example does have two interfaces, so you will always get two different names. The default configuration is "eth0". If the EtherCAT devices are connected to the second interface or to an interface with a different name, you have to edit the configuration file. If you want to find out which device name is used for the network interface, open a terminal and execute following command:


You will get a list of all network devices. Check the name of the available LAN interfaces. Now open the configuration file. We assume that the installation of the youBot driver was done as described in the manual.

 sudo gedit /opt/ros/[you_ros_version]/share/youbot_driver/config/youbot-ethercat.cfg

Change the name of the Ethernet device parameter to the name of your device.

EthernetDevice = eth0 #default, or eth1, eth2 .....

Mistake in configuration file

See The youBot base motor controller have to be of type: 174 or 1632

When controlling from external computer

Robot is turned off

Devices that are turned on usually works better.

Ethernet cable is wrongly connected

Proper cable connections are shown on a page Connecting youBot to external computer

Internal PC is turned on

When you want to control KUKA youBot with an external PC you have to be sure that internal PC is turned off.

Go back to Technical Support Software

Corrections, suggestions, and new documentation should be posted to the Forum.