Associated with: WITS Outstations
Security permission required to access this pick action: Off/On Scan
NOTE: The ability to place points and outstations Off Scan is disabled on most systems by default. (Its permission is typically denied on a per server basis.)
WARNINGUNEXPECTED BEHAVIOR OF APPLICATION
Use the Off Scan pick action on an Outstation with care—always check the Field Device’s current activity before deciding whether to use this action. Using the Off Scan action will mean that the Field Device will not log data or generate DNP3 events for all points. For this reason, you need to be certain that other users do not require the Field Device's point data before you put the Field Device Off Scan.
To check whether a Field Device is currently processing a request, look at its entry in the Current Request column of the Outstations List. You can also check a Field Device’s current activity via other displays, for example, the Outstation’s View Status window.
You can use the Off Scan action to set a Field Device that is currently 'on scan' to 'off scan'. When a Field Device is 'off scan':
- The Field Device does not log data or generate events for its points, but it can still generate events related to the Field Device, such as health check events.
- The Field Device will clear the ONLINE object flag for each of its points. For each point, it will also perform any action for ONLINE flag changes (see DNP3 Object Flag Actions).
- Configuration changes (upload and download ) can still be applied.
- Output points cannot be controlled (the Field Device will reject any controls).
- The On Scan/Off Scan state of the Field Device's points are ignored (if the Outstation is Off Scan, all of its points are treated as Off Scan points, even though they may be configured to On Scan). When the Outstation has Scanning enabled, its points return to the On Scan/Off Scan state they had before Scanning was disabled.
Typically, you would set an Outstation to Off Scan when you expect its points to generate unnecessary alarms and/or events, for example, during maintenance.
The current scanning state of a Field Device is shown in the View Status window for the WITS Outstation item
NOTE: The On Scan/Off Scan settings for points are independent of the Field Device's On Scan/Off Scan setting. However, both On Scan/Off Scan settings affect the scanning state for an individual point.
The scanning state of each point is a combination of its individual setting and the Field Device's OnScan/Off Scan setting. If either (or both) is Off Scan, the point is Off Scan. A point is only On Scan if both the Field Device and the point are On Scan.
Further Information
Set a WITS Outstation to be On Scan or Off Scan