Hi.
We’ve encountered a similar issue with the X20CS2770.
After performing a PLC software update followed by a restart, we sporadically see a BusOff condition on the module.
The strange part: this BusOff cannot be reset, even though CAN communication between other nodes on the bus resumes normally.
The only quick fix we’ve found so far is to completely remove the module from the base and re-insert it.
Unfortunately, we haven’t been able to monitor what’s happening on the physical bus layer during the PLC restart, so we’re not sure what exactly triggers the BusOff in the first place.
That said, the fact that the BusOff flag stays latched and can’t be cleared—even though the bus is back up—feels off.
We’ve discussed this with B&R support. They were able to reproduce the issue partially. Right now, the ball is in our court to identify what’s actually triggering the BusOff.
I’m currently on vacation, but I’ll follow up with more info once I’m back in the office.