The value based search enables you to specify numerical values or states of one or more process parameters. It will enable you to quickly observe all the periods that match your search criteria.
If you are interested in conditions such as shutdowns, temperatures below certain thresholds, pressures above a safety limit or valves that are fully open, the value based search will help you rapidly identify and visualize periods in the history of a process during which such events occurred.
Note: The value based search will search through the time period highlighted by the Context Bar. Time periods that are filtered out or not yet indexed, are excluded from the search.
- How to perform a value based search
- Setting up and editing search conditions
- Available conditions
- Add calculations
- Saving a search
How to perform a value based search
- Select a set of tags and the time period of interest.
- Within the search menu, click "Create new" under the Value based search option.
- Add the search conditions (see “Setting up and editing search conditions” below).
- Press the "Search" button to start the search.
- Wait for the result list to appear. By default, the results are sorted by date and descending (see working with the search result list to change the order of the results).
Navigate through the results list to find results of interest. Add them as additional layers to the focus chart by clicking the "Add layer" link.
Setting up and editing search conditions
- Select the tag or attribute of interest. Only active tags are available in the dropdown menu.
- Specify the condition and the value for the selected tag.
- For digital and string tags, when you use the condition “=”, you can select multiple states.
- Add multiple conditions by clicking on the “Add condition” link. Up to 10 conditions can be combined.
- By clicking on the logic operator in the value based search, the standard 'AND' operator between the conditions can be replaced by an 'OR' operator.
Note: Only one operator can be used over all search conditions. More complicated Boolean logic based on combinations of AND / OR / NOT operators are currently not supported. However, Filters can often be used to indirectly implement more complex logic.
- Adapt the minimum duration for which the results must match the specified conditions in the "Minimum duration" field. This parameter may be used to filter out noise (brief spikes that satisfy the specified Boolean conditions).
Note: The index resolution setting determines the maximum resolution at which results are available. This implies that with a resolution setting of 1 minute, no results will be found with a duration smaller than 1 minute.
Available conditions
Analog and discrete tags (numeric)
- Boolean conditions: '<, <=, >, >=, !=, =' are available.
- 'Constant': time periods in which the selected measurement is constant.
Digital and string tags (non-numeric)
- Equality '=': time periods with status equal to the selected state(s). It is possible to add multiple states. You can also search through all available states.
- 'Constant': time periods in which the selected measurement is constant. For instance, a batch ID tag with conditions 'Constant' would result in time periods corresponding to the individual batches.
Add calculations
It is possible to add one or multiple calculations to the search results and the search definition, by clicking on the "Add calculation" link. Please refer to the calculations on search results article for more information about calculations.
Saving a search
After creating or editing a search, to save it click on the link "Save this search" on the Search summary.
This action will open a panel, where you can specify:
- The search name,
- A description,
- And the location in the Work Organizer.
Click on the button "Save search" on the save search panel.
Note: A value based search can also be used as monitor once saved. To learn more about monitoring, refer to this article.