Unexpected loss of cyclic communication to IO Devices connected to Ethernet port 2

Under some circumstances the connection to Profinet IO Devices may unexpectedly be interrupted by IO Controller with error code "CPM DHT/Watchdog failure" although the IO Device has sent all expected cyclic frames.

The exact details of the issue and its reproducability are not 100% clear but only Ethernet port 2 seems to be affected by current knowledge.

This issue is independend of the existing network load or parallel traffic in network. It is already observed when only 2 IO Devices are connected to IO Controller.

Additing additional acyclic traffic (e.g. cyclic ReadRecord requests) may increase probability of the issue but even that is not 100% confirmed.