(UniInt) Disconnected Startup

These options set preferences for disconnected startup of a UniInt interface.

• Enable disconnected startup (with point caching)

  Interfaces built with UniInt version 4.3.0.0 or later include functionality to take advantage of disconnected startup, which allows the interface to start from a local cache file with or without a valid connection to the host PI Server. For more information on this feature, see the PI Universal Interface (UniInt) Framework user guide.

  Check Enable disconnected startup (with point caching) to enable the disconnected startup option. Disconnected startup cannot be used with the interface default setting, or if the PI SDK is enabled and retrieves point attribute information from the PI Server. Enable disconnected startup (with point caching) is disabled if either Enable PI SDK or Use the Interface's default setting are activated.

  The command line equivalent for enabling this option is /CacheMode.

• Cache synchronization period

  The Cache synchronization period specifies the time slice in milliseconds (ms) allocated by UniInt to synchronize the interface point cache file with the PI Server. By default, the interface synchronizes if running in disconnected startup mode. UniInt allocates a maximum number of ms for each pass through the control loop until the file is completely synchronized.

  Synchronization can be disabled by setting Cache synchronization period to 0. The default synchronization period is 250 ms, the minimum period is 50 ms, and the maximum period is 3000 ms (3s). Period values between 1 and 49 ms, and above 3000 ms are reset by the interface to match the minimum and maximum period values.

  Note: Take care when adjusting this parameter. The synchronization period value must be less than the smallest scan class period defined, or else input scans are missed while the point cache file is synchronized.

  The command-line equivalent for enabling this option is /CacheSynch=#.

• Cache Path

  The Cache Path specifies a directory in which to create the point caching files. The directory specified must already exist on the target machine. By default, the files are created in the same directory as the interface executable.

  The command-line equivalent for enabling this option is /CachePath=<path>.

• Cache Files

  Two cache files are used by the interface. If either file is missing when the interface starts, the interface will create the missing file. By default, cache files are created in the same directory as the interface executable. If the path to the executable cannot be established, the PI API provides a default location based on information available to the application.

  The file name is constructed using the executable name, host name, point source, and ID provided by the startup command file. The point cache file will have the form: filepath/exename_hostname_pointsource_id_ptcache.dat

  Likewise, the digital cache file will have the form: filepath/exename_hostname_pointsource_id_dgcache.dat

  Note: Part of creation includes storing interface and PI Server version information in each file to be used for validation. The connection to the PI Server must be available during the initial creation process for the disconnected startup operation to be configured correctly.

  The cache files store point configuration used during interface startup. After a successful startup, the files are updated at regular intervals during data collection pause periods. Normally, the files are updated automatically when any changes are made to the server. A cache file can also be purged and re-created manually using two buttons:

  • Rename Files

    Renames the cache files by appending the current time in seconds after the filename.

  • Delete Files

    Deletes the cache files.

    Cache files can only be renamed or deleted if not presently in use by the running interface. The buttons are enabled only when the interface is not running.