This method (as part of the OPC UA Mapper) serves as a diagnostic interface and exists for each SafetyProvider. For time series observation, this interface can be polled, e.g., by a diagnostic device. For details, refer to the OPC UA information model described, see Clause 6.1.4.

The diagnostic interface method does not take any input parameters and returns both the input- and output-parameters of the last call of the method ReadSafetyData.

Additionally, a 2-byte sequence number is added to the diagnostic interface, allowing for a detection of missed calls due to polling. The sequence number counts the number of accesses to ReadSafetyData.

A best practice recommendation is to store all input- and output-parameters if SComErr_diag is <> 0.