The Cached-Loadingoption provides a model where the transfer of the Software Packageand its installation are separate steps. To support the Cached-Loading model the Server has to providethe Current Versionand the Pending Version. Optionally the Fallback Versioncan be supported.

With the Current Versionthe Clientcan decice if an update is required and which version to transfer. With the Pending Versionthe Clientcan ensure to install the desired version. With the Fallback Versionthe Clientcan install an alternative version.

Software Packagesare transferred using the TemporaryFileTransferType (OPC 10000-5). The new software may be transferred in the background without stopping the device. The actual installation of the software can be done later using the installation option.

For Cached-Loadingthe CachedLoadingTypeis used, which is described in 8.4.5.