EtherCAT Error Messages

This section covers the following error messages linked to the EtherCATClosedEtherCAT is an open, high-performance Ethernet-based fieldbus system. The development goal of EtherCAT was to apply Ethernet to automation applications which require short data update times (also called cycle times) with low communication jitter (for synchronization purposes) and low hardware costs motion bus that are displayed in the Information and Logs window:

Working Counter failure limit exceeded due to failed node response to cyclic commands. Stopping EtherCAT network cyclic communication.
Link Error detected! Please, check controller connection.
Slave %s is not responding to acyclic frame. Please, check power supply or connection.

These messages can arise due to the following causes seen in the following table.

Error Case Description Results
Wrong / Missing Device

The XMLClosed"Extensible Markup Language " XML is a general-purpose markup language. It is classified as an extensible language because it allows its users to define their own tags network configuration file contains the list of all EtherCAT devices present in the network.

At the EtherCAT initialization phase, the master checks that:

  • Every physical device in the network corresponds to the configured devices
    (the master detects if the configuration does not match the physical devices)
  • The Standard I/O Couplers and I/O slices are correct by adding the proper commands in the network configuration file
    (this allows the detection of wrong or missing Standard I/O Coupler)

An Error log is generated with the relevant information.

The EtherCAT startup is aborted, as well as the startup of the machine.
Link Loss / Device Fault

This kind of error can appear anytime in the EtherCAT communication, typically when a cable is disconnected or cut or whenever an EtherCAT device is damaged.

The master has a mechanism that detects such situations.

An Error log is generated with the relevant information.

The EtherCAT communication is aborted.

If the network is cut, the drives on the side of the network disconnected from the master are moved into an error state (F29). They are automatically stopped and powered off.

In addition, all still-reachable axes have to be stopped and powered off.


  • It can be necessary to put the axes in a safe position before powering it off (this action is application dependent).
Frame Loss

For security, all frames sent must be received in a given timeout period (at least before the next cycle is started).

The master detects this case by managing the appropriate timeout watchdogs.

An Error log is generated with the relevant information.

The EtherCAT communication is aborted.
Working Counter

When EtherCAT master (KAS controller) sends out an EtherCAT datagram it sets the Working Counter (WC) value to 0. The nodes receiving the frame increment the WC at the hardware level according to a precise rule. When the controller receives the frame it compares the WC with the expected value to detect error conditions.

Possible Reasons for the Working Counter Error:

  • The slave EtherCAT device does not exist or cannot be physically reached due to connector/cable failure.
  • Slave hardware failure
  • Slave is still busy with a previous command and is not ready.
 The controller generates an A31 alarm and logs a warning message when the WC values does not match the expected value. When the controller detects three such working counter failures within 1000 EtherCAT frames, it generates an E30 error and shuts down the EtherCAT communication.

Other Messages Linked to EtherCAT

For more information see "Communication and Fieldbus"

The following message is displayed if an error or inconsistency is discovered during the parsing of the XML file when the application is started:

Unable to open EtherCAT config file <file-name>
<file-name>:<line>:<column>: <parsing error>

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