Defining Virtual IOW Tags

A Virtual Tag is a way of defining IOW Tags using dynamic expressions. Expression can be composed using PI Tags and built-in functions like:

• +, -, *, /
• MIN, MAX, MEAN, SUM, ABS, SQRT, STD
• If then else
• ( ) 

Creating Virtual Tags

To create a Virtual Tag:

• First create a new IOW.
• For the Variable select "Virtual Tag".
  Select the "Virtual Tag" Variable for your IOW.
• Now the Expression field becomes available. You can either click the Edit button and define the Expression right away, or do this later after you have saved your IOW.
• Remember to also fill in the other fields - refer to the IOW Record.

Opening the Expression

From the CL/System Details Page

To open the Expression from the CL Details Page (PEI Equipment) or System Details Page (PLSS Equipment):

• Scroll to the IOW section.
• Find your Virtual Tag (Variable = "Virtual Tag").
• Click on the PI/Virtual Tag field.

Click in the PI/Virtual Tag field. 

• Then click the Edit button the becomes available.

Click the Edit button.

• Now you can define the Expression.

From the IOW Details Page

To open the Expression from the IOW Details Page:

• In the Details section, click Edit.
• In the Expression field click on the Edit button.

The Virtual Tag Expression can also be opened from the IOW Details Page.

Below is an example where a Virtual Tag expression is defined and verified. You can select a PI Tag from the list and click the Add button to add the Tag to the expression. When done defining the expression, you can verify it by clicking the Test button.

A PI Tag is added to the expression with the Add button. The Test button is used to verify the expression.

When the Virtual Tag’s expression is verified, IMS will either show a green valid message or a red error message.

An error message is shown in case of, e.g., a syntax error in the expression. 

You can learn more about the Formula Editor here.

Tags search using wildcards

When adding Tags to the IOW (also when adding it to a Virtual Tag expression), you can search for the Tag name using wildcards in the search string. Valid examples are:

• *Test* (this is also default behavior when no wildcard is used)
• Test*
• *Test
• Test

Searching for a PI Tag using wildcards.