Intersection (BIntersectionBlock)
This block evaluates whether the Value In timestamp matches the Timestamp In timestamp. If they match, the algorithm passes the Value In to the Out. For a trend request the block filters out records where the two input timestamps do not match.
Figure 123. Intersection properties
To view these properties, double-click the block on the Wire Sheet or the block name in the Nav tree.
| Property | Value | Description |
|---|---|---|
| Out | read-only value slot | Outputs the filtered trend records from the Value In.
|
| Timestamp In | value slot | Links from the output of other logic blocks or data sources to identify timestamps to use from this trend to filter records
from the Value In trend.
|
| Value In | value slot | Links from the output of other logic blocks or data sources to identify values to use from this trend. |
Examples
An algorithm might use this block with a Logic Filter block that only passes a trend record when the waste valve position is closed (not dumping some liquid product to waste)
into an Intersection block as the Timestamp In. The Intersection block filters out any trend records from the Water Gallons data source linked into the Value In whenever there is not a record with the matching timestamp from the Logic Filter linked to the Timestamp In. In this case, both data sources have the same interval (15 minutes) but the Waste Valve Position data is potentially filtered so the result of the algorithm will likely have less than 96 records in a single day, meaning
no record whenever the Waste Value Position is open.
Figure 124. Intersection algorithm
In the next example, the two data sources have different intervals (day interval vs. 15 minute interval). The Intersection block normalizes (overrides) the 15-minute interval to return daily intervals to evaluate. In this case, there would be only
a single daily record at 12:00 am for both the Timestamp In and Value In slots so the block passes all of the records. The Intersection block is not really filtering, but the function of aligning the intervals and timestamps is something a Time filter cannot do on its own, at least not with needing to process records at 15-minute intervals and rollup the results to
daily values.
This example has one history that is time filtered for three shifts and then intersected to create a web chart. Each shift shows on the same chart.
Shift 1 is from 7:00 am - 4:00 pm
Shift 2 is from 4:00 pm - 12:00 am (midnight)
Shift 3 is from 12:00 am (midnight) - 7:00 am
The Wire Sheets for the three shifts follow.
Figure 125. Shift 1 algorithm
Figure 126. Shift 2 algorithm
Figure 127. Shift 3 algorithm
The following screen capture shows the data processed by the algorithms.
Figure 128. Data source
The following is a chart produced by the algorithms.
Figure 129. Chart
