EtherCat Diagnostic and Statistical Information
Written by Daniel Heslewood
Updated at June 5th, 2026
This article aims to assist users troubleshoot their EtherCAT network. This could be when errors or issues seem to appear intermittently or at random, with no obvious cause, or when multiple EtherCAT errors occur simultaneously in the standard troubleshooting log.
One of the benefits of the EtherCAT Networks is the ability to display detailed diagnostics and statistical information. In addition to the standard troubleshooter and error log, this information provides statistics on the communications frames sent and received by the EtherCAT master and slaves as well as the number of frames in which errors were detected.
You can use the diagnostic and statistical information to:
- Confirm that the EtherCAT network was correctly installed during commissioning or test runs.
- Identify the causes of communications errors that occur during normal operation.
- Checking the EtherCAT network line quality during normal operation.
It's important to note that this information will not directly specify the root cause of the issue, but rather point you in the right direction when diagnosing an EtherCAT network.
Displaying the Statistical Information In Sysmac Studio
- Start Sysmac Studio, and go online to the controller.
- Double click on the EtherCAT branch, under Configurations and Setup in the Multiview Explorer. Or right-click EtherCat and select Edit.
- Right-click on the EtherCAT master from the EtherCAT tab page and select Display Diagnosis/Statistical Information.
- The diagnostic and statistical information will be displayed.
Understanding The Information
The Diagnostics/ Statistics information presents one window with two sections.
- The Master Diagnosis/ Statistics information.
- The Slave Diagnosis/ Statistics information.
The following items are displayed for the master diagnostic and statistical information, if you cannot see all of these items, ensure that “Show all items is selected”. The highlighted sections indicate the labels that may increase in value if the the EtherCAT network is not operating normally. Further information on the definitions of these labels can be found later in this article, under the section Master Information Reference Table.
Some small increase is expected over long periods of time, usually we are concerned when there is an increase in a value, within a small amount of time. By clicking Get, you can update the statistical information. This will allow you to compare the increase since you initially opened the window, or since you last pressed Get.
If there is a significant increase of error frames detected in the master, you can presume there is an issue on the network. We can then use the Slave Diagnosis/ Statistics information to help identify the cause of the error.
Identifying the Cause of the Error
Here is an example network configuration, where we have detected a number of error frames on the EtherCAT network.
The number of error frames for the input port (PortA) for node address 4 is 31, so you can see that error frames were received on the input port for node address 4. Therefore, you can assume that there is a problem between the output port (PortB) for node address 3 and the input port for node address 4. This corresponds to location (A), (B) or (C) in the network configuration diagram.
With this information, you can assume the following possible error locations.
- The device at node address 3.
- The cable between the output port at node address 3 and the input port at node address 4 or the connectors at those ports.
- The device at node address 4.
Master Information Reference Table
The following table is produced from: Practices guide, EtherCAT Troubleshooting (P114-E1-01). Please refer to this catalog for references to page numbers.
The table also references the NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (Cat. No. W505)
Item |
Displayed information |
Assumed cause of increase |
Possible correction |
| Frame reception timeout count | The number of frame reception timeouts that occurred. | A cause to a Process Data reception Timeout occurred, which increases the Frame reception timeout count. The Frame reception timeout count will increase also when the count in the CRC Error Frames Received, Short frames received, or Overlength frames received increases. | Refer to EtherCAT Network Diagnostic Procedure on page 1-33. |
| Reception buffer overflow count | The number of frames discarded due to buffer overflows when receiving data. | There are too many frames on the EtherCAT network that are not EtherCAT frames. | See if there are computers or other non-EtherCAT devices connected to the EtherCAT network and remove them if there are any. |
| Non-EtherCAT frames received | The number of frames received other than EtherCAT frames. | There are frames on the EtherCAT network that are not EtherCAT frames. | See if there are computers or other non-EtherCAT devices connected to the EtherCAT network and remove them if there are any. |
| Link OFF count | The number of times link OFF was detected. | A cause to a Link OFF Error occurred. | Refer to the NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (Cat. No. W505) and remove the cause of the error. |
| Discarded process data receptions | The number of process data packets discarded when receiving process data. | Operations for which multi-execution is prohibited in Prohibition to Physically Disconnecting a Slave and Resetting an Error or Connecting a Slave at the Same Time on page 3-2 were executed. The value sometimes increases when the network is started or communicating EtherCAT slaves are replaced. | Refer to Prohibition to Physically Disconnecting a Slave and Resetting an Error or Connecting a Slave at the Same Time on page 3-2. |
| Discarded message receptions | The number of messages discarded in mailbox reception. | A cause to an EtherCAT Message Error occurred. | Refer to the NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (Cat. No. W505) and remove the cause of the error. |
| CRC Error Frames Received | The number of frames received that resulted in CRC errors. | The frames on the EtherCAT network are corrupted. | Refer to EtherCAT Network Diagnostic Procedure on page 1-33. |
| Frame reception errors | The number of frames resulting in reception errors from the Ethernet controller (EtherMAC). | The frames on the EtherCAT network are corrupted due to noise. | Implement noise countermeasures. |
| Collision count | The total number of delay collisions on the line after start of transmissions. | A repeater hub is connected. | You cannot use repeater hubs with EtherCAT communications. See if there are repeater hubs connected to the EtherCAT network and remove them if there are any. |
| Short frames received | The number of frames received with less than 64 bytes. | The frames on the Ether-CAT network are corrupted due to noise. Computers or other non-EtherCAT devices are connected. | Refer to EtherCAT Net-work Diagnostic Procedure on page 1-33. |
| Overlength frames received | The number of frames received with more than 1,522 bytes. | The frames on the EtherCAT network are corrupted due to noise. Computers or other non-EtherCAT devices are connected. | Refer to EtherCAT Network Diagnostic Procedure on page 1-33. |
If you require assistance diagnosing the EtherCAT network, save the information and send it to your local OMRON representative.
You can do this by selecting “Output File” while viewing the Diagnostic/ Statistical information. You will have the option to save as a CSV, or Viewer Format. The viewer format allows us to view the information just as you see it in your project. Save the file in a directory of your choice.
