data storm messages under systems tab
ABB has many PLCs in its family... please be specific.
The AC 800M has a built-in protection that isolates the controller if too many Ethernet telegrams are sent its way (measured in telegrams per second). Most (all?) Ethernet interfaces of AC 800M has this feature. Threshold ranges from 800 - 1600 telegrams/second depending on type of communication module.
There is a Technical Description available at ABB Library that details this protection, I suggest that you search, download and read it. Can’t recall the document ID, but search for ”storm protection” and it should pop up.
Most likely, network design is wrong, or improper protocols have been used, eg Spanning Tree which is more suitable for an office network than in an industrial control system. There are other more resilient protocols available, eg MRP (IEC 62439-2), Westermo/ABB FRNT, Hirschman HIPER Ring, Moxa Turbo Ring.
Ring structures are more difficult to to fault trace. The ring master must work flawlessly - cooperate with switch vendor. Verify correct firmware is in use. In worst case break up the ring into a flat network until you have sorted out what’s wrong.
Be careful with using VLAN technology - a LOT of the precious isolation go lost when truncing traffic together. Never trunc primary and secondary network in any place along the network.
ABB promotes using primary/secondary networks isolated from each other over a single ring. The hardware need to be doubled, but again, you are investing in true redundancy.
Find what loops the network and remove it.