For a DTM instance it is mandatory to provide the interface IOnlineOperation if the device provides online data. This interface is mapped to an object of type FdtTransferServiceType (see 7.8). Since the DTM interface is not mandatory for all devices, the availability of the TransferServices depends on the availability of the DTM interface. The member SupportedTransfer indicates, which TransferServices are supported for the device.
Table 67 – TransferService mapping
|
OPC |
FDT |
|||
|
BrowseName |
Interface |
Method |
Data member |
Description |
|
2:TransferToDevice |
IOnlineOperation |
BeginWriteDataToDevice / EndWriteDataToDevice |
- |
|
|
2:TransferFromDevice |
IOnlineOperation |
BeginReadDataFromDevice / EndReadDataFromDevice |
- |
|
|
2:FetchTransferResultData |
IOnlineOperation |
- |
- |
Retrieves the result / status from the executed methods. |
|
SupportedTransfer |
IOnlineOperation |
- |
SupportedTransfer |
|
The TransferServices Type object (with browse name “Transfer”) is provided as child node of an offline device node (not for an online device node).
For the method FetchTransferResultData the server is allowed to limit the TransferResultData in regard to the list of transferred parameters (parameterDefs) to zero data. The results of the transfer will be represented in the parameter values of the device node.