Logged Data for WITS Database Points

WITS Field Devices can support periodic logging of time-stamped point data. This means that point data can be logged at regular intervals in addition to being logged for events such as change of state.

If you require point data to be logged periodically, you need to consider:

• How often ClearSCADA retrieves the logged data from the Field Device. This is defined in the WITS Outstation configuration, see Specify the Polling Interval and Offset for Logged Data.
• How many logged data records will be created between each data retrieval.
• The logged data storage capacity of the Field Device.

If you enable periodic data logging for points, and set the Interval to a low amount, you may find that your Field Device becomes full. In this scenario, you can either configure the Outstation item to poll for logged data more frequently or you can increase the Interval for data logging on your points. This will result in the points' logged data being recorded less frequently.

To specify whether periodic Logged Data is used on a point, and if so, how frequently it is created:

1. Log on to ViewX via a user account that has the Configure permission, and then display the Form for the WITS database point (see Display a Form in the ClearSCADA Guide to Core Configuration).
2. Select the <Point Type> tab. For example, select the Analog Point tab on the Analog Point Form.
3. In the Logged Data section, use the Enabled check box to specify whether the Field Device logs periodic data for the point. (Select Enabled to log periodic data; clear Enabled to disable periodic data logging). If you select Enabled, you can define the other Logged Data settings (see steps 4 onwards).

4. Use the Interval setting to specify how often, in minutes, the Field Device will log data for the point. You can enter the value directly in the field, or use the Interval Window (accessed via the field’s browse button) to specify the required value. For more details, see OPC Time Format in the ClearSCADA Guide to Core Configuration.

   Example:

   Every 15 minutes:

   Interval: 15M

   Offset: 0

   Every hour at 30 minutes past the hour:

   Interval: 1H

   Offset: 30M

   NOTE: The permitted intervals are defined in the Device Profile for the Field Device (see Display a WITS Device Profile).

5. Use the Offset setting to specify the start time for the data logging. The amount of time, in seconds, you enter is added from the start of the week, which is midnight (in UTC) between Sunday and Monday.

   NOTE: The permitted offsets are defined in the Device Profile for the Field Device (see Display a WITS Device Profile).

6. If the point is a counter point, use the End of Period Reset Interval setting to define the period after which the Field Device will reset the counter to 0. If you enter a value of 0, then the Field Device will never reset the counter. You can enter the period directly, by using the OPC Time Format, or by using the Interval Window (accessed from the field's browse button). The device profile defines whether the Field Device supports this End of Period Reset capability (see Display a WITS Device Profile).

7. Save the configuration.

   NOTE: If you have enabled periodic logging for a point, you should also enable Historic and the Periodic historic data filter setting (see Historic Data Filter for WITS Database Points). This will allow ClearSCADA to store the periodic data in its historic database.

8. Download the configuration to the Field Device by using the Outstation item's Download Configuration (WITS Outstation) action.

   If your Field Device does not support download configuration, you will need to make the same changes to the Field Device's configuration locally.

Further Information

Defining Historic Details for a Point in the ClearSCADA Guide to Core Point Configuration