RecordInputDataObjectElement does not deliver expected IO data if no AR exists

Using the acyclic Read Record service it is possible to read the cyclic process data via index 0x8028 (RecordInputDataObjectElement ).

If no AR exists it is expected to deliver the "real data of the submodule" according to Profinet Service specification.

Test setup is as follows:

• Configure IO Device with one input submodule
• set IO data for this input submodule to 0xFF
• acyclically read RecordInputDataObjectElement

Expected behavior: The acylic service returns 0xFF

Observed behavior: The acyclic service returns 0 (or sometimes even other arbitrary value).

If an AR exists (a connection to an IO Controller), the acyclic service returns the expected data. As sool as the AR is gone, the acyclic service delivers wrong data.