SOEM for ROS

Table of Contents

• SOEM ROS Package Upgrade
• Package Description
• Installation
• Usage
• Development

SOEM ROS Package Upgrade

This package has been upgraded to the new Release of the upstream SOEM repo v1.4.0. This upgrade brings not only the new release, but also uses colcon as build tool. This allows you to use soem from within your regular ROS workspace. So you don't need to specify ${soem_INCLUDE_DIRS}/soem in the include_directories section of your package anymore.

Package Description

SOEM is an open source EtherCAT master library written in C. Its primary target is Linux but can be adapted to other OS and embedded systems.

SOEM has originally been hosted at http://developer.berlios.de/projects/soem/ but has been moved to GitHub and the OpenEtherCATsociety organisation.

This package contains the upstream SOEM repository as a git submodule and wraps it to be easily used within ROS 2.

Disclaimer: This package is not a development package for SOEM, but rather a wrapper to provide SOEM to ROS 2. In the end, this just provides the CMake quirks that allows releasing SOEM as a ROS 2 package.

All bug reports regarding the original SOEM source code should go to the bugtracker at https://github.com/OpenEtherCATsociety/SOEM/issues.

Obviously, any support, being it bug reports or pull requests (obviously preferred) are highly welcome!

Usage

To use soem in your ROS package add the following to your package.xmland CMakeLists.txt, respectively.

In your package.xml add:

  <build_depend>soem</build_depend>
  <exec_depend>soem</exec_depend>

and in your CMakeLists.txt, add it to find_package and adapt the include_directories as shown:

find_package(catkin REQUIRED COMPONENTS
  ...
  soem
  ...
)

include_directories(
  ...
  ${catkin_INCLUDE_DIRS}
)

Running without sudo/root

SOEM requires access to certain network capabilities as it is using raw sockets, and as such any executable linking against SOEM needs to be run with certain privileges. Typically, you run any SOEM executables with sudo or as root. This is impractical for any ROS system, and as such there exists a tool called ethercat_grant that helps with that.

Install with

sudo apt install ros-<DISTRO>-ethercat-ethercat_grant

and add the following to your your node tag in your launchfile

launch-prefix="ethercat_grant

Development

With the integration of the upstream SOEM repo as a git subtree, and a major overhaul of the build system, it is now possible to use the soem ROS package easily from your regular ROS workspace.

Simply clone this repository into your workspace

git clone https://github.com/cplasberg/soem.git

change into that repo

cd <foo/bar>/soem

and load the submodule

git submodule init
git submodule update

Note that if you want to update or patch the subtree which includes the SOEM upstream repository, you need to be sure to do this properly. When creating this, I followed the instructions in this Atlassian blog post. This covers all the things you need.