Configure a specific value detector

The configuration is basically the same for analog and discrete specific value detectors, with only a few small differences.

To configure a specific value detector

1. In the Detector Type list, select Analog Specific Value or Discrete Specific Value.

   

2. In the Time Interval box, type the interval, in milliseconds, at which the system checks to see if the event conditions specified by the detector occurred. This value must be greater than or equal to 500 milliseconds, and less than or equal to 1 hour (3600000 ms).

   Be careful when assigning time intervals to event tags. For more information, see Time intervals for SQL-based detectors .

3. In the Edge Detection list, select the "edge" for the event detection.

   A leading edge detection returns only rows that are the first to successfully meet the criteria (return true) after a row did not successfully meet the criteria (returned false). A trailing edge detection returns only rows that are the first to fail the criteria (return false) after a row successfully met the criteria (returned true). For an edge detection of "both," all rows satisfying both the leading and trailing conditions are returned.

   For more information, see Edge detection for events (wwEdgeDetection) .

4. In the Tag Name box, type the name of the tag to which the event criteria will be applied. To search the database for a tag, click Search. The Tag Finder dialog box appears, in which you can query the database for tags. For more information, see Use the tag finder.

5. Set the value criteria for the tag.

   If you are configuring an analog specific value detector, in the Operator box, select an operator for the criteria. Then, in the Detection Value box, type a value against which the stored values for the tag are compared to determine if the event occurred.

   

   If you are configuring a discrete specific value detector, in the State Value list, select the target state of the discrete tag that causes the event to occur.

   

6. If you selected None in Edge Detection list, you can specify a resolution for the data. In the Resolution box, type a sampling rate, in milliseconds, for retrieving the data in cyclic mode. The system returns values stored over the requested time period at the interval specified by the resolution. For example, if you specify a 5000 ms resolution, the system queries for all data during the time period and then only returns those values that occur at each 5000 ms interval, starting with the start date and ending with the end date.