You can configure a Promotion window for the Primary Phase scan. The Promotion window is a defined amount of time, during which, ClearSCADA will only attempt to scan promoted outstations for primary data (current data).
At the start of the Promotion scan window for the Primary Phase, ClearSCADA scans those outstations that are in the promoted state for primary data. The outstations are scanned in address order (ascending). The other outstations are not scanned during this time.
When the Promotion scan window ends, ClearSCADA makes a record of which outstations it had scanned. When the next Promotion scan window begins, it will resume the scans from the point it was scanning when the previous Promotion scan window ended.
When the Promotion scan window has expired, the ‘normal’ scan period begins. During the ‘normal’ scan period, ClearSCADA will attempt to retrieve primary data from all of the outstations, including those that have not been promoted.
When the ‘normal’ scan period ends, ClearSCADA makes a record of which outstations it had scanned. When the next ‘normal’ scan period begins, ClearSCADA will resume scanning from the point it was scanning when the previous ‘normal’ scan period ended.
To specify the duration for a Promotion window, enter the required period in the Promoted Scan field on the Form(s) for the Channel(s) that a Promoted outstation is to use (see Define the Permitted Scan Durations).
When specifying a Promoted Scan, you should consider the Recommended Settings for Scan Durations.