Understanding EtherCAT ESI Files

An EtherCAT SubDevice Information (ESI) file is a standardized XML-based document that acts as an instruction manual for an EtherCAT SubDevice. It provides all the necessary details required for an EtherCAT MainDevice to configure and communicate with a specific SubDevice.

By using ESI files from all SubDevices in a network, engineers can efficiently configure the entire EtherCAT system using tools like acontis EC-Engineer, which then saves the device and network configuration as an ENI (EtherCAT Network Information) file.

Key Information Contained in an ESI File

An ESI file describes one or more EtherCAT SubDevices and contains:

  • SubDevice Type – Defines whether the device is an I/O module, servo drive, or another type of EtherCAT device.
  • EtherCAT Interface Details – Provides information on the physical connection and communication parameters.
  • Supported Mailbox Protocols – Specifies which protocols are supported, such as CoE (CANopen over EtherCAT).
  • Synchronization Settings – Helps configure the device’s timing behavior in the EtherCAT network.
  • Process Data Mapping – Describes the input and output process data structure, ensuring proper data exchange between the device and the network.

 

How are ESI Files Used?

When setting up an EtherCAT network, the ESI file for each SubDevice is loaded into the EtherCAT configuration tool, such as EC-Engineer. This tool parses the ESI file to determine the correct device configuration, sets up the EtherCAT data frames, establishes communication with the connected SubDevices, and generates an EtherCAT Network Information (ENI) file to be used by the MainDevice, such as EC-Master.

Here’s a simplified process of how ESI files are used:

1. Loading ESI Files:

The user scans the network for or manually imports the ESI files for all SubDevices into the configuration software.

2. Network Configuration:

The configuration software compiles all of the ESI files together, defines the network topology, and establishes the process data structure for all of the SubDevices on the network. The configuration software then generates an ENI (EtherCAT Network Information) file, which allows the MainDevice to understand the functionality, capabilities, and specific configuration of each SubDevice.

3. Initializing the Network:

The MainDevice configures the network, sets communication parameters, and initializes data exchange according to the details specified in the ESI and ENI files.

4. Operation:

The MainDevice then brings the network to Operational State and communicates with the SubDevices, exchanging data and controlling the system based on the configurations defined in the ESI files.

 

Why Are ESI Files Important?

ESI files play a crucial role in simplifying EtherCAT network configuration. By defining how each SubDevice interacts within the network, they allow for:

  • Automated Configuration: Ensures seamless setup by providing all necessary device parameters.
  • Efficient Integration: Reduces manual effort when adding new devices to an EtherCAT system.
  • Standardized Communication: Ensures compatibility across different manufacturers and device versions.

 

 

Where Can You Find ESI Files?

Manufacturers typically provide ESI files for download on their websites. When selecting an ESI file, it’s essential to:

  • Choose the correct file version – Devices may receive firmware updates that affect ESI file contents.
  • Verify compatibility – Ensure the ESI file matches the specific product model and revision.

However, in some cases, users may need to modify or create their own ESI files, especially when custom SubDevices or new features are involved. In such cases, having a solid understanding of the XML structure used in ESI files is important. Users creating custom SubDevices are encouraged to contact the EtherCAT Technology Group for free resources, such as the ESI Specification, as well as tools for SubDevice and ESI file development.

 

Key Takeaways

ESI files are an essential component in configuring and managing EtherCAT networks. They simplify device integration, ensure device compatibility, and facilitate fast, accurate communication between MainDevices and SubDevices. Understanding how ESI files work and ensuring that the correct ESI file is used for each SubDevice is key to building robust EtherCAT networks both large and small. By leveraging ESI files, engineers can efficiently set up and maintain EtherCAT networks with minimal manual intervention.

For more information on EtherCAT networks and ESI files, please contact us or explore the resources on our website.