In Hyper Historian, you can use calculated tags and calculation triggers to configure complex calculations. You can use performance calculations to provide totals over time, and statistics for analysis. These calculations are performed only on historical data stored in Hyper Historian. You can also use these calculations for setting up alarms or faults for certain conditions that may occur over time.
For example, you may want to schedule maintenance for a machine every 10,000 hours of run time or every 1,000 cycles. In this case, you can create a calculation tag that calculates the amount of time the tag is in the TRUE state, and another calculation tag that counts the number of times the machine has been switched on. A third calculation tag can monitor the incoming values for the first two tags, and can generate an alarm when a predetermined threshold has been reached for maintenance.
Performance calculations can be triggered periodically or on any data change event, using flexible new date/time, mathematical, string and historical data retrieval functions that are part of the ICONICS Expression Editor. Calculations can use scalar values, historical values, or string operations, along with a wide variety of functions within an enhanced version of the ICONICS Expression Engine, and results are calculated automatically on each trigger, or can be recalculated manually on demand.
Calculated tags take as their input normal incoming values from Hyper Historian tags and perform calculations on historical data. The results of these calculations are stored in the Hyper Historian database. You can nest calculated tags so that they can be used as input to other calculated tags. These calculations are triggered using calculation triggers -- these are triggers that are created specifically for use with calculated tags. Calculation triggers are different than regular triggers because they can point to historical dates and times, whereas regular triggers cannot. Calculation triggers also make use of special functions that are available only to them, for use with calculation tags. These unique functions are described in the Performance Calculation Functions topic.
Configuration of a new Performance Calculation tag is easy. Simply add a new Calculated Tag in the existing hierarchical structure of the Hyper Historian Workbench configurator; you can organize calculated tags in folders and subfolders. Each Performance Calculation appears as a new tag in the Hyper Historian browser, and can therefore be accessed, replayed, analyzed, and reported on just like other Hyper Historian data values.
Hyper Historian offers several preconfigured calculations out-of-the-box such as standard deviation and variance, and you can customize your own Performance Calculations using the Expression Editor, with equation parsing and syntax checking.
To configure calculated tags you must do the following:
Add calculated tags to the folders where you store your Hyper Historian tags (refer to the Configuring a Calculated Tag topic).
Create calculation triggers that will execute the calculations, and add these triggers to your calculated tags (refer to the Creating a Calculation Trigger topic).
Set up recalculation options in the System Administration node (refer to the Scheduling Recalculation Tasks topic).
Note you can import configuration information from an Excel spreadsheet, an XML file, or a CSV file. For more information, refer to the Importing and Exporting Hyper Historian Configurations topic. Once imported, you can edit imported information as needed.