We are occasionally facing a CAN Bus-Off issue with the X20CS1070 module. When the fault occurs, the module enters an error state with the red LED blinking, and the CANBusOff flag remains TRUE continuously. Once the module enters this state, we are unable to recover it through the application. The only way to restore communication is by performing a warm restart of the PLC or a power cycle.
After investigating the issue, we found that the latest firmware for the X20CS1070 includes a fix that provides automatic recovery from the CAN Bus-Off state (B&R ID: TDYD-8654). However, this firmware is supported only with Automation Studio 4.x, whereas our application is developed in Automation Studio 3.9. Due to project constraints, migrating the entire project to AS4.x is currently not feasible. The error occurs once in two weeks or a month. We checked hardware side and it looks okay, as a simple warm start will resolve the issue.
Our current observations are:
- The CAN Bus-Off condition occurs occasionally.
- The X20CS1070 remains in the Bus-Off state indefinitely.
- The CANBusOff flag stays TRUE and cannot be cleared through the application.
- The module does not recover automatically.
- A warm restart or power cycle is required to restore operation.
Could anyone please suggest:
- Is there any method to reset or recover the X20CS1070 from the Bus-Off state through the application in AS3.9 without warm start?
- Is there any firmware version compatible with AS3.9 that includes the Bus-Off recovery improvement?
- Are there any recommended workarounds or configuration changes to avoid or recover from this condition without restarting the PLC?
We are currently using:
- Automation Studio 3.9
- PP400 (PP450) series power panel PLC with integrated HMI
- X20CS1070 Firmware: 1.5.0.0
Any suggestions or experience with this issue would be greatly appreciated.
Thank you.
Hi @Shridhar_Moger ,
I’m sorry, but the community won’t be able to help with this specific issue. Since you mentioned a firmware update that might solve the problem, you will first need to provide more data. Please collect the raw data when the error occurs, and then contact our Support team. This will allow our R&D department to confirm if the new firmware includes the fix you need.
I don’t know if we have a workaround with the same effect of the firmware fix.
Ciao
Valerio
The CAN bus off state occurs when the X20CS1070 receives to many error frames.
You should investigate why these errors occurs and solve these errors.
Causes could be EMC related, length of cable, terminating resistor, baudrate.
The CAN bus off is not a normal state and should never occur.
With a warmstart only the can error counters are reset.
We have thoroughly checked the hardware and did not find any issues. The machine operates normally for several days or even months without any communication problems. However, the issue occurs occasionally and without any apparent pattern and occurs on random machines.
When the fault occurs, even after removing the TB connector and resetting the CAN function block through the application, the X20CS1070 module remains in the Error state and does not recover.
Please find the attached screenshots captured from the machine during the fault condition for your reference.
We found that the latest firmware release notes for the X20CS1070 include the following update as shown. Is it something related module reset after CAN bus off state?
Kindly review the observations and let us know if any additional information or diagnostic data is required. We would appreciate your support in identifying the issue.
Thanks
Hi,
The X20CS1070 has limited ability to diagnose the CAN bus.
Corne has already listed some possible causes for you.
I would add ‘a defective CAN device in your network’.
A CAN diagnostic tool like this one might also help you:
PCAN-USB: PEAK-System
The firmware upgrade may improve the reset of a “Bus-Off” condition, but it does not eliminate the cause of the “Bus-Off.”
At least, that is how I would interpret the information from the upgrade.
