Currently There are no standard mapping specifications between the OPC DA Error code and OPC UA error code. It exists only in the COM Interop source code.

Also some of the error codes such as E_INVALID_PID don’t have equivalent mapping.

Based on this, we have come up with our own mapping that includes the ones from the COM Interop code. This mapping is in the attached file.

But even with this mapping, we have had issues. Below is an example:

This is based on the mapping of OPC DA error code E_UNKNOWNITEMID mapped to OPC UA status code of BadNodeIdUnknown .

If a User perform a Read on a NodeID mapped to ItemId in OPC DA but gets a operation status code of BadNodeIdUnknown, He does not know if the item does not exist in OPC DA Server or OPC UA server (both cases are valid).

The current solution to the problem is to include the OPC DA error code (HRESULT) in the Diagnostic Info to distinguish it from a OPC UA error.

Suggestion:
It would be useful to have specific OPC UA Status codes related to legacy OPC errors (such as OPC DA) or even provide similar specification as above so that vendor can conform to standard status codes and it becomes easier to trouble shoot issues.