4.10.7.4 Redundancy Support in Device-DTM

A DTM able to handle a redundant device provides additional information within it's parameter document.

After an OnAddChild() complete redundant address information can be given by the parent component to the Device-DTM. The Device-DTM is then able to detect if it's appropriate slave is used as redundant slave. This complete address information must be used by the Device-DTM within a IFdtCommunication::ConnectRequest(), but can also be used for diagnosis and status information. Typically now additional redundancy handling is required within the Device-DTM itself.

A DTM handling a redundant device must check all addresses provided during a SetParameter() call. If the Device-DTM is not able to handle this addresses, e.g., because only a vendor-specific offset can be used, an error message should be created and a FALSE should be returned to the calling parent component. In this case the parent component is able to detect Device-DTMs which can not be used at the redundant fieldbus. A Device-DTM must save all redundancy information in it's instance dataset.

A DTM representing a redundant slave can be used as child of a non redundant aware parent component. In this case the Device-DTM must not use the additional FDT redundancy functionality, dialogs or redundant specific contents of FDT xml documents.