– Could NOT find ros_ethercat_eml (missing: ros_ethercat_eml_DIR)
– Could not find the required component ‘ros_ethercat_eml’. The following CMake error indicates that you either need to install the package with the same name or change your environment so that it can be found.
CMake Error at /opt/ros/noetic/share/catkin/cmake/catkinConfig.cmake:83 (find_package):
Could not find a package configuration file provided by “ros_ethercat_eml”

解决办法：

sudo apt-get install ros-noetic-ros-ethercat-eml