possible packet loss when using PNS_IF_REMOVE_DIAG_REQ while alarm pending

When a PNS_IF_REMOVE_DIAG_REQ service is performed for a diagnosis record with pending PNS_IF_SEND_DIAG_ALARM_REQ the later requests's packet may never be returned to host.

This will typically not happen in the field as IO Controllers tend to answer to diagnosis alarms quite fast. However misbehaving IO Controllers or bad timing using Profinet IO Tester (certification tool) may show this error.

Workaround: Wait until PNS_IF_SEND_DIAG_ALARM_CNF is returned by netX before sending PNS_IF_REMOVE_DIAG_REQ for the same diagnosis.