Sometimes PPM IRT frames are not sent when large IO data configuration is used

In some cases the Profinet Device Switch implementation might not send an IRT frame during the Red phase. The problem occurs under a certain overlow situation of internal counters which is not handled properly.

The problem might be not seen with small amoutns of submodules. The behavior can be reproduced using an amount of IO data of (400Bytes or more in combination with at least seven submodules.

In ususal configurations, the behavior does not lead to an AR abort with an PLC. The problem is seen in case the DHT watchdog is configured to value 1 (resulting in an AR abort) or when the SPIRTA test is run.