knx/tp error

[Daniel]

Siemens KNX UART v5.2

There is known issue with this chip. Siemens fixed it in version 5.3.
In certain conditions the issue which you described is happening.
Check voltage on KNX as above 30V this was happening. The biggest issues were with combination of SE KNX PSU.
Check if you don't have some script which is creating a knx loop
Check if some device on KNX network is not spamming the bus.

If nothing help we could replace this chip on your LM. I assume your device is out of warranty already as it is old one.

BR