First, read this article on how to install EtherCAT on your system and how to run a demo application without EEROS.

If the demo application runs successfully, you can write your own EEROS application with EtherCAT.

Once the EtherCAT stack has been installed and the demo application is running, the ecmasterlib can be installed.

Clone, build and install ecmasterlib :

$ cd path/to/working/directory
$ git clone url-to-ecmasterlib
$ cd ecmasterlib
$ mkdir build-x86-64
$ cd build-x86-64
$ cmake -DCMAKE_INSTALL_PREFIX=/absolute/path/to/working/directory/install-x86-64 ..
$ make
$ make install

Build and install EEROS after you have installed ecmasterlib Install EEROS as described in this tutorial, but use the command line option -DUSE_ETHERCAT=TRUE when calling cmake.

...
cmake -DCMAKE_INSTALL_PREFIX=/absolute/path/to/working/directory/install-x86-64 -DUSE_ETHERCAT=TRUE ..
...