Enabling logging for a shared variable is a two-step process. First, you must enable logging and configure logging options in the Project Library Properties dialog box. You then can enable logging on the Logging page of the Shared Variable Properties dialog box when you create the shared variable.
After you enable logging, the Shared Variable Engine (SVE) acquires data from all shared variables for which you have enabled logging. The SVE then sends the data to the Citadel database. Citadel determines the appropriate location in the database for the data and logs the data in the database.