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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 used slaves
  2. An EtherCAT Master that can scan the network
  3. Software that can create an ENI file

The ENI files can be optained from the manufacturer.

  • Maxon MAXPOS 50/5 Downloads –> Handbücher –> English –> MAXPOS 50/5 ESI File (englisch, ZIP 48 KB)
  • Elmo:
    • Are installed with the 'EAS II' software from Elmo in Elmo Motion Control/Elmo Application Studio II/EtherCATSlaveLib
    • Can be dwonloaded here TODO

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.

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. Select a slave
  2. 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
  3. Attach a slave to the EC master (If EC-Engineer is used by Acontis, attach the slave to the PC)
  4. The slave must be supplied with power.
  5. Scan the network
  6. The slave should be detected
  7. Test if you can read an encoder value
  8. Connect the complete EC network and scan again
  9. Define the period duration for PDOs (typically 1msec)
  10. Define all variables which are to be sent or received with the PDOs from the slaves.
  11. Export the ENI file

If one of the following points changes, then the ENI file must be rebuild:

  • Topology
  • Period duration
  • Exchanged variables via PDO