SOEM for ROS

IMPORTANT INFORMATION

SOEM ROS Package Upgrade Announcement

To any consumers of the SOEM ROS package:

This package will be upgraded to the new Release of the upstream SOEM repo v1.4.0. The upgrade via this PR on GitHub will happen on the

31st of August 2019

This upgrade will bring not only the new release, but also changes to the catkin plumbing. This allows you to use soem from within your regular ROS workspace. No more jumping through the hoops required, that are described in the Usage section.

The changes to the build system are backwards compatible.

Changes in upstream SOEM, however, might not be! Please test the above linked PR and provide feedback until the merge deadline, if you are a heavy user of this library.

The current state of the SOEM ROS package has been tagged with v1.3.0 if you cannot use the new version.

Table of Contents

Package Description
Installation
Usage
Development

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 original SOEM C code provided by the Technische Universiteit Eindhoven, the development of which has been taken over by rt-labs. As the original source is down, it is not totally clear what the state of this package is with respect to the upstream repository. It is, however, approximately the one merged in OpenEtherCATsociety/SOEM#1.

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

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

All ROS related issues should target the bug tracker on GitHub (but might be redirected ;-)).

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

Installation

If soem has been released for your respective ROS distribution, you can simply install it using

sudo apt install ros-<DISTRO>-soem

Currently, soem has been released for ROS indigo, kinetic and melodic. If you want to use soem from source, please check out the section about Development.

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(
  ...
  ## The following work around allows SOEM headers to include other SOEM headers.
  ## SOEM headers assume all headers are installed in a flat directory structure
  ## See https://github.com/mgruhler/soem/issues/4 for more information.
  ${soem_INCLUDE_DIRS}/soem
)

Note that this assumes you have installed soem from apt or followed the setup layed out in the Development section!

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. Tis 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

If you want to use soem in ROS using a ROS distro it has not been released for, or build it from source, you need to make sure to use it from an install space. In its current state, this repo is doing some copying of header files during the installation step, which is not done and thus will not work in regular build/devel space layouts.

Thus, if you want to use soem from source, it is encouraged that you put this in an underlay install space.

This has been tested using both, catkin_make and catkin build.