An expression is any calculation that returns a result.  Expressions might be mathematic calculations, comparisons of tag values, date and time functions or text functions to create messages that vary according to conditions.

Expressions are found as a data source option within a wide variety of VTS tags. For example:

 

•   Analog Control, I/O tab configuration

•   MultiWrite tag, trigger tab configuration:

•   Alarm tag, trigger tab configuration:

•   Expressions can also be used to create custom page titles for parameterized pages and are frequently used in calculation and function tags. 

 

 

Parts of the expression display:

 

In the following topics, you will find examples of functions that can be used in expressions.  These will be only a small sub-set of the functions that are available.  For a complete list and description of VTS functions please refer to the VTS Programmer’s Guide:  Functions Arranged by Topic.