Create an ENI File

Purpose of the ENI File

The ENI file describes the EtherCAT network. This file describes the topology in which all slaves in the network are connected. It also describes which values are exchanged periodically.

In addition to the topology, the type of slaves must also be known. The different types of EtherCAT slaves are described in the ESI files.

See Understanding EtherCAT for more information.


To create an ENI file the following is required:

  1. ESI files describing the slaves, see ENI_and_ESI_files
  2. An EtherCAT Master that can scan the network
  3. Software that can create an ENI file

Items 2 and 3 can be covered with the software EC-Engineer. This software already includes a software EtcherCAT master. The EtherCAT network can then be attached to the Ethernet port of the PC and scanned by the software. This software is not free of charge. Please make sure to run the program with administrator rights.

Alternatively, you can download the free software EASII (Elmo Application Studio 2) from Elmo. In this case you need a hardware EtherCAT master from Elmo, e.g. the Gold Maestro from Elmo.

Create ENI file

The exact procedure depends on the software used. However, the following procedure can always be used:

  1. Use ClassA master
  2. Select a slave
  3. The EASII already has all ESI files for the Elmo Drives. If the required ESI file is not yet available:
    1. Get the ESI file from the manufacturer
    2. Import the ESI file
  4. Attach a slave to the EC master (If EC-Engineer is used by Acontis, attach the slave to the PC)
  5. The slave must be supplied with power.
  6. Scan the network
  7. The slave should be detected
  8. Test if you can read an encoder value
  9. Connect the complete EC network and scan again
  10. Define the period duration for PDOs (typically 1msec)
  11. Define all variables which are to be sent or received with the PDOs from the slaves.
  12. Export the ENI file

If one of the following properties changes, then the ENI file must be rebuilt:

  • Topology
  • Period duration
  • Exchanged variables via PDO

With EC-Engineer you can Switch to Diagnosis Mode where you can plot selected values in realtime.

IMPORTANT If you use EEROS together with EtherCATInterface (ecmasterlib and EtherCATInterface) you have to make sure that the PDOs specified in the ENI file matches the definitions in the Headerfile Interface/EtherCATInterfaceElmo_config.hpp, see Adaptions