Except that the diagram might be inclomplete regarding correct UML (return calls are missing),
it is only surprising that the DTM sends OnScanResponse() without ScanRequest().
And of course, the DTM should modify the parameter XML between GetParameters() and SetParameters().
From my point of view, there should be a UML self-call inserted.
Funny that SetChildrenAddresses() was written well here, but not in the interface definition.
I changed it to the interface definition so that correct hyperlinks will be provided.