3.7.3 Scenarios

3.7.3.1 Parent Component Version 1.2

A DTM of FDT version higher than 1.2 will not get version information from the communication channel because IFdtCommunicationEvents::OnConnectResponse() is called. In this case such a DTM can only use FDT1.2 compatible communication documents.

3.7.3.2 Parent Component newer than Version 1.2

A DTM of FDT version higher than 1.2 will get version information from the communication channel because IFdtCommunicationEvents2::OnConnectResponse2() is called by the parent component. Such a DTM must use communication documents compatible to the FDT version provided by the parent component.

3.7.3.3 DTM Version 1.2

The DTM does not expose the interface IFdtCommunicationEvents2. A parent component higher than 1.2 must call IFdtCommunicationEvents::OnConnectResponse().

3.7.3.4 Nested Communication

Within nested communication the version number returned by a Gateway-DTM depends on the functionality of it’s parent component.

If the Gateway-DTM is at a higher version number than the parent component then the Gateway-DTM :

• can return the same version as the parent and provide the functionality according to this version or
• can emulate the higher functionality if possible. Then the Gateway-DTM must guarantee that all required functionality is provided by it’s parent.

Examples:

• A DTM of a Profibus – HART Remote I/O can support HART FDT communication compatible to FDT version 1.2.1 although it’s parent component supports only FDT version 1.2. In this case the Remote I/O DTM must be able to map all FDT1.2.1 HART transaction requests (e.g. HART burst mode) to appropriate FDT 1.2 profibus compatible transaction requests
• A Multiplexer DTM of version 1.2.1 with a parent component supporting only FDT version 1.2 may not be able to provide functionality of the higher FDT version (e.g. because it depends on device initiated datat transfer).