Getting Started with SOEM Application

EtherCAT (Ethernet for Control Automation Technology) is an Ethernet-based fieldbus system. It is a widely used protocol for industrial applications. In this tutorial, I will show you how to install and consume an open source EtherCAT master implementation, SOEM (Simple Open EtherCAT Master), and discover devices on a EtherCAT network in a ROS workspace.

For more information, visit https://github.com/OpenEtherCATsociety/SOEM.

Prerequisite

  • You have a machine with Windows 10 installed.
  • You have ROS Melodic Desktop Full installed.
  • You have a EtherCAT slave controller commissioned to work.
  • You have a EtherCAT network topology configured physically.
  • You have basic knowledge to EtherCAT technology.

Step 1: Add SOEM Library to your Workspace

Firstly, you will need a catkin workspace to begin with. Let's assume you are working on an empty workspace under c:\ethercat_ws. You can install SOEM from vcpkg:

:: install vcpkg SOEM port
c:\ethercat_ws> vcpkg install SOEM:x64-windows

Step 2: Create your own Package

Now you have the required libraries. Let's begin with a new package and build with SOEM.

:: change the directory to the source subfolder.
c:\ethercat_ws> cd src

:: create your owned package
c:\ethercat_ws\src> catkin_create_pkg my_pkg

Step 3: Add SOEM Application Code

Copy slaveinfo.c into the new package as the SOEM application code to run.

:: make the directory to store the source.
c:\ethercat_ws> mkdir src\my_pkg\src

:: download the source of `slaveinfo.c`
c:\ethercat_ws> curl https://raw.githubusercontent.com/OpenEtherCATsociety/SOEM/master/test/linux/slaveinfo/slaveinfo.c -o src\my_pkg\src\slaveinfo.c

Step 4: Edit CMakeLists.txt

You will also needs to edit the src\my_pkg\CMakeLists.txt to author the new executable and to be explicit on SOEM as dependency.

Here is the CMake recipe to add to look for SOEM:

find_path(winpcap_INCLUDE_DIRS NAMES pcap.h)
find_library(winpcap_LIBRARY NAMES wpcap)
find_library(packet_LIBRARY NAMES packet)
find_path(soem_INCLUDE_DIRS NAMES ethercat.h PATH_SUFFIXES soem)
find_library(soem_LIBRARY NAMES soem)

Here is the recipe to author the slaveinfo.c as an excutable:

include_directories(
  ${catkin_INCLUDE_DIRS}
  ${soem_INCLUDE_DIRS}
  ${winpcap_INCLUDE_DIRS}
)

add_executable(${PROJECT_NAME}_node src/slaveinfo.c)

set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME slaveinfo PREFIX "")

add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

target_link_libraries(${PROJECT_NAME}_node
  ${catkin_LIBRARIES}
  ${soem_LIBRARY}
  ${winpcap_LIBRARY}
  ${packet_LIBRARY}
  Ws2_32.lib Winmm.lib
)

Step 5: Build the Workspace

Let's build the workspace to produce the executables and binaries. And remember to run setup.bat to add the development space into the current environment.

:: Build the workspace
c:\ethercat_ws> catkin_make

:: Add the development space into the current environment.
c:\ethercat_ws> devel\setup.bat

Step 6: Check EtherCAT Network

Let's check the EtherCAT network to make sure the SOEM and the EtherCAT network is working.

First, retrieve the list of ethernet adapter discovered on your machine.

c:\ethercat_ws> rosrun my_pkg slaveinfo

SOEM (Simple Open EtherCAT Master)
Slaveinfo
Usage: slaveinfo ifname [options]
ifname = eth0 for example
Options :
 -sdo : print SDO info
 -map : print mapping
Available adapters
Description : Microsoft, Device to use for wpcap: \Device\NPF_{7B78D297-ED15-4C1B-BC32-8EDB9E41E5AB}
Description : VMware Virtual Ethernet Adapter, Device to use for wpcap: \Device\NPF_{8BBA06A7-8AAB-48B5-90E3-DC2DB31D86F6}
Description : Microsoft, Device to use for wpcap: \Device\NPF_{BF10C5FD-EF74-4D93-B32E-D0D2A040BA87}
Description : Microsoft Corporation, Device to use for wpcap: \Device\NPF_{894B5E76-A359-4AAF-8F7C-41FAD68773E3}
Description : Microsoft, Device to use for wpcap: \Device\NPF_{A54146EA-CD6F-4A95-93E4-0919C4B2D685}
Description : VMware Virtual Ethernet Adapter, Device to use for wpcap: \Device\NPF_{144028BF-951B-4209-B8D4-30E888BFB4CB}
End program

Look for the ethernet adapter for your EtherCAT network and take a note of the path, for example, \Device\NPF_{A54146EA-CD6F-4A95-93E4-0919C4B2D685}.

Now run the slaveinfo with the ethernet device path again to list what EtherCAT slave controllers are discovered on the network. You should see information similar to the below and check that the details make sense to your environment.

c:\ethercat_ws> rosrun soem slaveinfo \Device\NPF_{A54146EA-CD6F-4A95-93E4-0919C4B2D685}

Slave:1
 Name:simco drive 40028083-00-0
 Output size: 48bits
 Input size: 48bits
 State: 4
 Delay: 0[ns]
 Has DC: 0
 Activeports:1.1.0.0
 Configured address: 1002
 Man: 0000010a ID: 0262c7b3 Rev: 00010211
 SM0 A:1000 L: 512 F:00010026 Type:1
 SM1 A:1400 L: 512 F:00010022 Type:2
 SM2 A:1800 L:   6 F:00010064 Type:3
 SM3 A:1950 L:   6 F:00010020 Type:4
 FMMU0 Ls:0000000a Ll:   6 Lsb:0 Leb:7 Ps:1800 Psb:0 Ty:02 Act:01
 FMMU1 Ls:00000027 Ll:   6 Lsb:0 Leb:7 Ps:1950 Psb:0 Ty:01 Act:01
 FMMUfunc 0:1 1:2 2:0 3:0
 MBX length wr: 512 rd: 512 MBX protocols : 0c
 CoE details: 27 FoE details: 01 EoE details: 00 SoE details: 00
 Ebus current: 0[mA]
 only LRD/LWR:0
PDO mapping according to CoE :
  SM2 outputs
     addr b   index: sub bitl data_type    name
  [0x000A.0] 0x6040:0x00 0x10 UNSIGNED16   Controlword
  [0x000C.0] 0x60FF:0x00 0x20 INTEGER32    Target Velocity
  [0x0010.0] 0x0000:0x00 0x00
  [0x0010.0] 0x0000:0x00 0x00
  [0x0010.0] 0x0000:0x00 0x00
  [0x0010.0] 0x0000:0x00 0x00
  [0x0010.0] 0x0000:0x00 0x00
  [0x0010.0] 0x0000:0x00 0x00
  SM3 inputs
     addr b   index: sub bitl data_type    name
  [0x0027.0] 0x6041:0x00 0x10 UNSIGNED16   Statusword
  [0x0029.0] 0x6064:0x00 0x20 INTEGER32    Position Actual Value
  [0x002D.0] 0x0000:0x00 0x00
  [0x002D.0] 0x0000:0x00 0x00
  [0x002D.0] 0x0000:0x00 0x00
  [0x002D.0] 0x0000:0x00 0x00
  [0x002D.0] 0x0000:0x00 0x00
  [0x002D.0] 0x0000:0x00 0x00

Summary

Now you have a workspace to continue the learning of SOEM. In this tutorial, I walk through the steps of installing SOEM from vcpkg, how to edit catkin package to consume SOEM, and how to run slaveinfo to exercise your EtherCAT network. I encourge you to read on the official SOEM tutorial to learn more about how to program SOEM application.