InduSoft Web Studio - InduSoft Corporation

InduSoft Web Studio
Tutorial training – Revision B – Sep/10/2000
© Copyright InduSoft Ltd. 2000
5. Tag Database Configuration
Tags are variables used in screens and task worksheets. Tags can be communication points in the
field equipment, results of calculations, alarm points, and so forth. User-created tags are called
application tags; tags predefined by InduSoft Web Studio are called internal tags. You can use
either type of tag with any InduSoft Web Studio module; the only difference is that internal tags
have predetermined functions. Tag values are stored in the Application Database.
Tag syntax rules:
• It can be composed of letters, numbers, and the underscore character (_).
• It must begin with a letter.
• Its maximum length is 32 characters (for a tag), or 16 characters (for a class member).
• The tag name must be different from internal tag names and math functions.
• Tag names are NOT case sensitive.
Examples: Temperature, pressure1, count
InduSoft Web Studio does not differentiate between uppercase and lowercase characters.
However, you can use both uppercase and lowercase characters to make names more clear
(Example: TankLevel instead of tanklevel).
Types of Tags
The value of a tag can be one of the four standard types:
Boolean (4 bytes): Boolean or digital variable (0 or 1).
Integer (4 bytes): Integer number (positive, negative, or zero). Equivalent to the C type long
integer. (with a range of –2147483647 to 2147483647)
Real (floating point, 8 bytes): Real number internally stored as a double word. Equivalent to the
C type double.
String (ASCII, 256 bytes): Character string up to 255 characters (from 0 to 254) that holds
letters, numbers, or special characters.
Examples: Recipe product X123, 01/01/90, *** On ***
All tags are declared in the Application Database module of the Database tab. In addition to the
four types previously listed, you can define new types called classes.
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