Writing a calculation tag when a tag hits a certain value.

Version 19.1.1 will be the first release that has the calculation server. The calculation server will enable calculations to be applied to tags and recorded back into the Historian. Here is an example of how to write a tag:

• If version 19.1.1 has not been installed this is the first step.
• Drill into the Calculation tile and you will see a blank screen.
• At the top right of the screen is a button saying ADD that will need clicked.
• Give the expression a name in the top field. For this example we will call it 5 Fault. 
• Backfill To will enable the user to apply the calculation to the tags historical data. For this example we will calculate it from Oct 25 12 a.m. until the present time. 
• Frequency gives the ability to run calculations on current data value changes or a periodic time interval. By selecting periodic interval of 5m, we will run the calculation for 5 minute intervals. 

• Next press the small plus sign next to details to write the actual equations. 
• This will give the ability to write many expressions to the specified group name. For this group we will only write 1 expression. By using the if calculation, we can write (Historian=localhost, Dataset=test 10, Tag=Tag0100) = 5 the expression is true and will record. If this is not true, it will put out no output.

• Functions, tags, and operators can be selected from the right panel.  

• Next, fill out the "dataset.new tag name" into the Tag field. The dataset will need to already be created before this point. We highly recommend creating a separate data set for calculated tags and trouble shooting future issues.    

The Evaluate button will help to make sure it is a valid equation. If it will not run as calculation it will give a line count to help trouble shoot any syntax errors.

• After the calculation has been written, hit apply and close on the right hand panel.
• The calculation should now appear along with a stop or play button. To calculate the expression hit the green play button. 

• The Status panel on the left should now read with active calculations.