The FileTransfer Object is of type TemporaryFileTransferType as defined in OPC 10000-5. It is used to create temporary files for download and upload of the software.

In the TemporaryFileTransferType type the GenerateFileForRead and GenerateFileForWrite Methods take an unspecified generateOptions Parameter. For the FileTransfer Object an Enumeration of type SoftwareVersionFileType is used for this Parameter. It is used to select the file to upload or download. All allowed values are defined in Table 101. Additional Result Codes of the GenerateFileForRead and GenerateFileForWrite Methods are specified in Table 74.

Table 74 – TemporaryFileTransferType Result Codes

Result Code	Description
Bad_InvalidState	If the PrepareForUpdate is available, the UpdateBehavior requires preparation and the PrepareForUpdate state machine is not in the state PreparedForUpdate.
Bad_NotFound	If there is no file to read from the device.
Bad_NotSupported	If the device does not support to upload / download of the Software Package.

For all errors that occur during the file transfer the ErrorMessage Variable should provide an error message for the user.

It is implementation dependent which version (see SoftwareVersionFileType in 8.5.1) is readable and which one is writable. Additional restrictions are defined in the concrete sub-types of PackageLoadingType.

The software is transferred as a single package. File type and content are device specific. If WriteBlockSize is supported, the Client shall write the file in chunks of this size.

The software should be validated during the transfer process. Errors shall be indicated either in the Write Method, the CloseAndCommit Method or an asynchronous completion of the file transfer. If the validation is performed synchronous, the Method returns Bad_InvalidArgument; if the validation is performed asynchronous, the error is indicated by the Error state of the FileTransferStateMachineType. If the ErrorMessage Variable is provided, it shall contain an error message representing the validation error.

The FileTransfer Object may optionally support the transfer of a Software Package from the device to the Client.

If this transfer is not supported, the Server shall return the Result Code Bad_NotSupported. If it is supported but there is currently no data, the Result Code Bad_NotFound shall be used instead.